Commit graph

582 commits

Author SHA1 Message Date
Huang Ying
c6833e1000 memory tiering: rate limit NUMA migration throughput
In NUMA balancing memory tiering mode, if there are hot pages in slow
memory node and cold pages in fast memory node, we need to promote/demote
hot/cold pages between the fast and cold memory nodes.

A choice is to promote/demote as fast as possible.  But the CPU cycles and
memory bandwidth consumed by the high promoting/demoting throughput will
hurt the latency of some workload because of accessing inflating and slow
memory bandwidth contention.

A way to resolve this issue is to restrict the max promoting/demoting
throughput.  It will take longer to finish the promoting/demoting.  But
the workload latency will be better.  This is implemented in this patch as
the page promotion rate limit mechanism.

The number of the candidate pages to be promoted to the fast memory node
via NUMA balancing is counted, if the count exceeds the limit specified by
the users, the NUMA balancing promotion will be stopped until the next
second.

A new sysctl knob kernel.numa_balancing_promote_rate_limit_MBps is added
for the users to specify the limit.

Link: https://lkml.kernel.org/r/20220713083954.34196-3-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: osalvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zhong Jiang <zhongjiang-ali@linux.alibaba.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-09-11 20:25:54 -07:00
Linus Torvalds
6614a3c316 - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe
Lin, Yang Shi, Anshuman Khandual and Mike Rapoport
 
 - Some kmemleak fixes from Patrick Wang and Waiman Long
 
 - DAMON updates from SeongJae Park
 
 - memcg debug/visibility work from Roman Gushchin
 
 - vmalloc speedup from Uladzislau Rezki
 
 - more folio conversion work from Matthew Wilcox
 
 - enhancements for coherent device memory mapping from Alex Sierra
 
 - addition of shared pages tracking and CoW support for fsdax, from
   Shiyang Ruan
 
 - hugetlb optimizations from Mike Kravetz
 
 - Mel Gorman has contributed some pagealloc changes to improve latency
   and realtime behaviour.
 
 - mprotect soft-dirty checking has been improved by Peter Xu
 
 - Many other singleton patches all over the place
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Merge tag 'mm-stable-2022-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:
 "Most of the MM queue. A few things are still pending.

  Liam's maple tree rework didn't make it. This has resulted in a few
  other minor patch series being held over for next time.

  Multi-gen LRU still isn't merged as we were waiting for mapletree to
  stabilize. The current plan is to merge MGLRU into -mm soon and to
  later reintroduce mapletree, with a view to hopefully getting both
  into 6.1-rc1.

  Summary:

   - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe
     Lin, Yang Shi, Anshuman Khandual and Mike Rapoport

   - Some kmemleak fixes from Patrick Wang and Waiman Long

   - DAMON updates from SeongJae Park

   - memcg debug/visibility work from Roman Gushchin

   - vmalloc speedup from Uladzislau Rezki

   - more folio conversion work from Matthew Wilcox

   - enhancements for coherent device memory mapping from Alex Sierra

   - addition of shared pages tracking and CoW support for fsdax, from
     Shiyang Ruan

   - hugetlb optimizations from Mike Kravetz

   - Mel Gorman has contributed some pagealloc changes to improve
     latency and realtime behaviour.

   - mprotect soft-dirty checking has been improved by Peter Xu

   - Many other singleton patches all over the place"

 [ XFS merge from hell as per Darrick Wong in

   https://lore.kernel.org/all/YshKnxb4VwXycPO8@magnolia/ ]

* tag 'mm-stable-2022-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (282 commits)
  tools/testing/selftests/vm/hmm-tests.c: fix build
  mm: Kconfig: fix typo
  mm: memory-failure: convert to pr_fmt()
  mm: use is_zone_movable_page() helper
  hugetlbfs: fix inaccurate comment in hugetlbfs_statfs()
  hugetlbfs: cleanup some comments in inode.c
  hugetlbfs: remove unneeded header file
  hugetlbfs: remove unneeded hugetlbfs_ops forward declaration
  hugetlbfs: use helper macro SZ_1{K,M}
  mm: cleanup is_highmem()
  mm/hmm: add a test for cross device private faults
  selftests: add soft-dirty into run_vmtests.sh
  selftests: soft-dirty: add test for mprotect
  mm/mprotect: fix soft-dirty check in can_change_pte_writable()
  mm: memcontrol: fix potential oom_lock recursion deadlock
  mm/gup.c: fix formatting in check_and_migrate_movable_page()
  xfs: fail dax mount if reflink is enabled on a partition
  mm/memcontrol.c: remove the redundant updating of stats_flush_threshold
  userfaultfd: don't fail on unrecognized features
  hugetlb_cgroup: fix wrong hugetlb cgroup numa stat
  ...
2022-08-05 16:32:45 -07:00
Linus Torvalds
7c5c3a6177 ARM:
* Unwinder implementations for both nVHE modes (classic and
   protected), complete with an overflow stack
 
 * Rework of the sysreg access from userspace, with a complete
   rewrite of the vgic-v3 view to allign with the rest of the
   infrastructure
 
 * Disagregation of the vcpu flags in separate sets to better track
   their use model.
 
 * A fix for the GICv2-on-v3 selftest
 
 * A small set of cosmetic fixes
 
 RISC-V:
 
 * Track ISA extensions used by Guest using bitmap
 
 * Added system instruction emulation framework
 
 * Added CSR emulation framework
 
 * Added gfp_custom flag in struct kvm_mmu_memory_cache
 
 * Added G-stage ioremap() and iounmap() functions
 
 * Added support for Svpbmt inside Guest
 
 s390:
 
 * add an interface to provide a hypervisor dump for secure guests
 
 * improve selftests to use TAP interface
 
 * enable interpretive execution of zPCI instructions (for PCI passthrough)
 
 * First part of deferred teardown
 
 * CPU Topology
 
 * PV attestation
 
 * Minor fixes
 
 x86:
 
 * Permit guests to ignore single-bit ECC errors
 
 * Intel IPI virtualization
 
 * Allow getting/setting pending triple fault with KVM_GET/SET_VCPU_EVENTS
 
 * PEBS virtualization
 
 * Simplify PMU emulation by just using PERF_TYPE_RAW events
 
 * More accurate event reinjection on SVM (avoid retrying instructions)
 
 * Allow getting/setting the state of the speaker port data bit
 
 * Refuse starting the kvm-intel module if VM-Entry/VM-Exit controls are inconsistent
 
 * "Notify" VM exit (detect microarchitectural hangs) for Intel
 
 * Use try_cmpxchg64 instead of cmpxchg64
 
 * Ignore benign host accesses to PMU MSRs when PMU is disabled
 
 * Allow disabling KVM's "MONITOR/MWAIT are NOPs!" behavior
 
 * Allow NX huge page mitigation to be disabled on a per-vm basis
 
 * Port eager page splitting to shadow MMU as well
 
 * Enable CMCI capability by default and handle injected UCNA errors
 
 * Expose pid of vcpu threads in debugfs
 
 * x2AVIC support for AMD
 
 * cleanup PIO emulation
 
 * Fixes for LLDT/LTR emulation
 
 * Don't require refcounted "struct page" to create huge SPTEs
 
 * Miscellaneous cleanups:
 ** MCE MSR emulation
 ** Use separate namespaces for guest PTEs and shadow PTEs bitmasks
 ** PIO emulation
 ** Reorganize rmap API, mostly around rmap destruction
 ** Do not workaround very old KVM bugs for L0 that runs with nesting enabled
 ** new selftests API for CPUID
 
 Generic:
 
 * Fix races in gfn->pfn cache refresh; do not pin pages tracked by the cache
 
 * new selftests API using struct kvm_vcpu instead of a (vm, id) tuple
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm updates from Paolo Bonzini:
 "Quite a large pull request due to a selftest API overhaul and some
  patches that had come in too late for 5.19.

  ARM:

   - Unwinder implementations for both nVHE modes (classic and
     protected), complete with an overflow stack

   - Rework of the sysreg access from userspace, with a complete rewrite
     of the vgic-v3 view to allign with the rest of the infrastructure

   - Disagregation of the vcpu flags in separate sets to better track
     their use model.

   - A fix for the GICv2-on-v3 selftest

   - A small set of cosmetic fixes

  RISC-V:

   - Track ISA extensions used by Guest using bitmap

   - Added system instruction emulation framework

   - Added CSR emulation framework

   - Added gfp_custom flag in struct kvm_mmu_memory_cache

   - Added G-stage ioremap() and iounmap() functions

   - Added support for Svpbmt inside Guest

  s390:

   - add an interface to provide a hypervisor dump for secure guests

   - improve selftests to use TAP interface

   - enable interpretive execution of zPCI instructions (for PCI
     passthrough)

   - First part of deferred teardown

   - CPU Topology

   - PV attestation

   - Minor fixes

  x86:

   - Permit guests to ignore single-bit ECC errors

   - Intel IPI virtualization

   - Allow getting/setting pending triple fault with
     KVM_GET/SET_VCPU_EVENTS

   - PEBS virtualization

   - Simplify PMU emulation by just using PERF_TYPE_RAW events

   - More accurate event reinjection on SVM (avoid retrying
     instructions)

   - Allow getting/setting the state of the speaker port data bit

   - Refuse starting the kvm-intel module if VM-Entry/VM-Exit controls
     are inconsistent

   - "Notify" VM exit (detect microarchitectural hangs) for Intel

   - Use try_cmpxchg64 instead of cmpxchg64

   - Ignore benign host accesses to PMU MSRs when PMU is disabled

   - Allow disabling KVM's "MONITOR/MWAIT are NOPs!" behavior

   - Allow NX huge page mitigation to be disabled on a per-vm basis

   - Port eager page splitting to shadow MMU as well

   - Enable CMCI capability by default and handle injected UCNA errors

   - Expose pid of vcpu threads in debugfs

   - x2AVIC support for AMD

   - cleanup PIO emulation

   - Fixes for LLDT/LTR emulation

   - Don't require refcounted "struct page" to create huge SPTEs

   - Miscellaneous cleanups:
      - MCE MSR emulation
      - Use separate namespaces for guest PTEs and shadow PTEs bitmasks
      - PIO emulation
      - Reorganize rmap API, mostly around rmap destruction
      - Do not workaround very old KVM bugs for L0 that runs with nesting enabled
      - new selftests API for CPUID

  Generic:

   - Fix races in gfn->pfn cache refresh; do not pin pages tracked by
     the cache

   - new selftests API using struct kvm_vcpu instead of a (vm, id)
     tuple"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (606 commits)
  selftests: kvm: set rax before vmcall
  selftests: KVM: Add exponent check for boolean stats
  selftests: KVM: Provide descriptive assertions in kvm_binary_stats_test
  selftests: KVM: Check stat name before other fields
  KVM: x86/mmu: remove unused variable
  RISC-V: KVM: Add support for Svpbmt inside Guest/VM
  RISC-V: KVM: Use PAGE_KERNEL_IO in kvm_riscv_gstage_ioremap()
  RISC-V: KVM: Add G-stage ioremap() and iounmap() functions
  KVM: Add gfp_custom flag in struct kvm_mmu_memory_cache
  RISC-V: KVM: Add extensible CSR emulation framework
  RISC-V: KVM: Add extensible system instruction emulation framework
  RISC-V: KVM: Factor-out instruction emulation into separate sources
  RISC-V: KVM: move preempt_disable() call in kvm_arch_vcpu_ioctl_run
  RISC-V: KVM: Make kvm_riscv_guest_timer_init a void function
  RISC-V: KVM: Fix variable spelling mistake
  RISC-V: KVM: Improve ISA extension by using a bitmap
  KVM, x86/mmu: Fix the comment around kvm_tdp_mmu_zap_leafs()
  KVM: SVM: Dump Virtual Machine Save Area (VMSA) to klog
  KVM: x86/mmu: Treat NX as a valid SPTE bit for NPT
  KVM: x86: Do not block APIC write for non ICR registers
  ...
2022-08-04 14:59:54 -07:00
Linus Torvalds
b167fdffe9 This cycle's scheduler updates for v6.0 are:
Load-balancing improvements:
 ============================
 
 - Improve NUMA balancing on AMD Zen systems for affine workloads.
 
 - Improve the handling of reduced-capacity CPUs in load-balancing.
 
 - Energy Model improvements: fix & refine all the energy fairness metrics (PELT),
   and remove the conservative threshold requiring 6% energy savings to
   migrate a task. Doing this improves power efficiency for most workloads,
   and also increases the reliability of energy-efficiency scheduling.
 
 - Optimize/tweak select_idle_cpu() to spend (much) less time searching
   for an idle CPU on overloaded systems. There's reports of several
   milliseconds spent there on large systems with large workloads ...
 
   [ Since the search logic changed, there might be behavioral side effects. ]
 
 - Improve NUMA imbalance behavior. On certain systems
   with spare capacity, initial placement of tasks is non-deterministic,
   and such an artificial placement imbalance can persist for a long time,
   hurting (and sometimes helping) performance.
 
   The fix is to make fork-time task placement consistent with runtime
   NUMA balancing placement.
 
   Note that some performance regressions were reported against this,
   caused by workloads that are not memory bandwith limited, which benefit
   from the artificial locality of the placement bug(s). Mel Gorman's
   conclusion, with which we concur, was that consistency is better than
   random workload benefits from non-deterministic bugs:
 
      "Given there is no crystal ball and it's a tradeoff, I think it's
       better to be consistent and use similar logic at both fork time
       and runtime even if it doesn't have universal benefit."
 
 - Improve core scheduling by fixing a bug in sched_core_update_cookie() that
   caused unnecessary forced idling.
 
 - Improve wakeup-balancing by allowing same-LLC wakeup of idle CPUs for newly
   woken tasks.
 
 - Fix a newidle balancing bug that introduced unnecessary wakeup latencies.
 
 ABI improvements/fixes:
 =======================
 
 - Do not check capabilities and do not issue capability check denial messages
   when a scheduler syscall doesn't require privileges. (Such as increasing niceness.)
 
 - Add forced-idle accounting to cgroups too.
 
 - Fix/improve the RSEQ ABI to not just silently accept unknown flags.
   (No existing tooling is known to have learned to rely on the previous behavior.)
 
 - Depreciate the (unused) RSEQ_CS_FLAG_NO_RESTART_ON_* flags.
 
 Optimizations:
 ==============
 
 - Optimize & simplify leaf_cfs_rq_list()
 
 - Micro-optimize set_nr_{and_not,if}_polling() via try_cmpxchg().
 
 Misc fixes & cleanups:
 ======================
 
 - Fix the RSEQ self-tests on RISC-V and Glibc 2.35 systems.
 
 - Fix a full-NOHZ bug that can in some cases result in the tick not being
   re-enabled when the last SCHED_RT task is gone from a runqueue but there's
   still SCHED_OTHER tasks around.
 
 - Various PREEMPT_RT related fixes.
 
 - Misc cleanups & smaller fixes.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:
"Load-balancing improvements:

   - Improve NUMA balancing on AMD Zen systems for affine workloads.

   - Improve the handling of reduced-capacity CPUs in load-balancing.

   - Energy Model improvements: fix & refine all the energy fairness
     metrics (PELT), and remove the conservative threshold requiring 6%
     energy savings to migrate a task. Doing this improves power
     efficiency for most workloads, and also increases the reliability
     of energy-efficiency scheduling.

   - Optimize/tweak select_idle_cpu() to spend (much) less time
     searching for an idle CPU on overloaded systems. There's reports of
     several milliseconds spent there on large systems with large
     workloads ...

     [ Since the search logic changed, there might be behavioral side
       effects. ]

   - Improve NUMA imbalance behavior. On certain systems with spare
     capacity, initial placement of tasks is non-deterministic, and such
     an artificial placement imbalance can persist for a long time,
     hurting (and sometimes helping) performance.

     The fix is to make fork-time task placement consistent with runtime
     NUMA balancing placement.

     Note that some performance regressions were reported against this,
     caused by workloads that are not memory bandwith limited, which
     benefit from the artificial locality of the placement bug(s). Mel
     Gorman's conclusion, with which we concur, was that consistency is
     better than random workload benefits from non-deterministic bugs:

        "Given there is no crystal ball and it's a tradeoff, I think
         it's better to be consistent and use similar logic at both fork
         time and runtime even if it doesn't have universal benefit."

   - Improve core scheduling by fixing a bug in
     sched_core_update_cookie() that caused unnecessary forced idling.

   - Improve wakeup-balancing by allowing same-LLC wakeup of idle CPUs
     for newly woken tasks.

   - Fix a newidle balancing bug that introduced unnecessary wakeup
     latencies.

  ABI improvements/fixes:

   - Do not check capabilities and do not issue capability check denial
     messages when a scheduler syscall doesn't require privileges. (Such
     as increasing niceness.)

   - Add forced-idle accounting to cgroups too.

   - Fix/improve the RSEQ ABI to not just silently accept unknown flags.
     (No existing tooling is known to have learned to rely on the
     previous behavior.)

   - Depreciate the (unused) RSEQ_CS_FLAG_NO_RESTART_ON_* flags.

  Optimizations:

   - Optimize & simplify leaf_cfs_rq_list()

   - Micro-optimize set_nr_{and_not,if}_polling() via try_cmpxchg().

  Misc fixes & cleanups:

   - Fix the RSEQ self-tests on RISC-V and Glibc 2.35 systems.

   - Fix a full-NOHZ bug that can in some cases result in the tick not
     being re-enabled when the last SCHED_RT task is gone from a
     runqueue but there's still SCHED_OTHER tasks around.

   - Various PREEMPT_RT related fixes.

   - Misc cleanups & smaller fixes"

* tag 'sched-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits)
  rseq: Kill process when unknown flags are encountered in ABI structures
  rseq: Deprecate RSEQ_CS_FLAG_NO_RESTART_ON_* flags
  sched/core: Fix the bug that task won't enqueue into core tree when update cookie
  nohz/full, sched/rt: Fix missed tick-reenabling bug in dequeue_task_rt()
  sched/core: Always flush pending blk_plug
  sched/fair: fix case with reduced capacity CPU
  sched/core: Use try_cmpxchg in set_nr_{and_not,if}_polling
  sched/core: add forced idle accounting for cgroups
  sched/fair: Remove the energy margin in feec()
  sched/fair: Remove task_util from effective utilization in feec()
  sched/fair: Use the same cpumask per-PD throughout find_energy_efficient_cpu()
  sched/fair: Rename select_idle_mask to select_rq_mask
  sched, drivers: Remove max param from effective_cpu_util()/sched_cpu_util()
  sched/fair: Decay task PELT values during wakeup migration
  sched/fair: Provide u64 read for 32-bits arch helper
  sched/fair: Introduce SIS_UTIL to search idle CPU based on sum of util_avg
  sched: only perform capability check on privileged operation
  sched: Remove unused function group_first_cpu()
  sched/fair: Remove redundant word " *"
  selftests/rseq: check if libc rseq support is registered
  ...
2022-08-01 11:49:06 -07:00
Paolo Bonzini
63f4b21041 Merge remote-tracking branch 'kvm/next' into kvm-next-5.20
KVM/s390, KVM/x86 and common infrastructure changes for 5.20

x86:

* Permit guests to ignore single-bit ECC errors

* Fix races in gfn->pfn cache refresh; do not pin pages tracked by the cache

* Intel IPI virtualization

* Allow getting/setting pending triple fault with KVM_GET/SET_VCPU_EVENTS

* PEBS virtualization

* Simplify PMU emulation by just using PERF_TYPE_RAW events

* More accurate event reinjection on SVM (avoid retrying instructions)

* Allow getting/setting the state of the speaker port data bit

* Refuse starting the kvm-intel module if VM-Entry/VM-Exit controls are inconsistent

* "Notify" VM exit (detect microarchitectural hangs) for Intel

* Cleanups for MCE MSR emulation

s390:

* add an interface to provide a hypervisor dump for secure guests

* improve selftests to use TAP interface

* enable interpretive execution of zPCI instructions (for PCI passthrough)

* First part of deferred teardown

* CPU Topology

* PV attestation

* Minor fixes

Generic:

* new selftests API using struct kvm_vcpu instead of a (vm, id) tuple

x86:

* Use try_cmpxchg64 instead of cmpxchg64

* Bugfixes

* Ignore benign host accesses to PMU MSRs when PMU is disabled

* Allow disabling KVM's "MONITOR/MWAIT are NOPs!" behavior

* x86/MMU: Allow NX huge pages to be disabled on a per-vm basis

* Port eager page splitting to shadow MMU as well

* Enable CMCI capability by default and handle injected UCNA errors

* Expose pid of vcpu threads in debugfs

* x2AVIC support for AMD

* cleanup PIO emulation

* Fixes for LLDT/LTR emulation

* Don't require refcounted "struct page" to create huge SPTEs

x86 cleanups:

* Use separate namespaces for guest PTEs and shadow PTEs bitmasks

* PIO emulation

* Reorganize rmap API, mostly around rmap destruction

* Do not workaround very old KVM bugs for L0 that runs with nesting enabled

* new selftests API for CPUID
2022-08-01 03:21:00 -04:00
Eric W. Biederman
d80f7d7b2c signal: Guarantee that SIGNAL_GROUP_EXIT is set on process exit
Track how many threads have not started exiting and when the last
thread starts exiting set SIGNAL_GROUP_EXIT.

This guarantees that SIGNAL_GROUP_EXIT will get set when a process
exits.  In practice this achieves nothing as glibc's implementation of
_exit calls sys_group_exit then sys_exit.  While glibc's implemenation
of pthread_exit calls exit (which cleansup and calls _exit) if it is
the last thread and sys_exit if it is the last thread.

This means the only way the kernel might observe a process that does
not set call exit_group is if the language runtime does not use glibc.

With more cleanups I hope to move the decrement of quick_threads
earlier.

Link: https://lkml.kernel.org/r/87bkukd4tc.fsf_-_@email.froward.int.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2022-07-20 10:23:51 -05:00
John Keeping
401e4963bf sched/core: Always flush pending blk_plug
With CONFIG_PREEMPT_RT, it is possible to hit a deadlock between two
normal priority tasks (SCHED_OTHER, nice level zero):

	INFO: task kworker/u8:0:8 blocked for more than 491 seconds.
	      Not tainted 5.15.49-rt46 #1
	"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
	task:kworker/u8:0    state:D stack:    0 pid:    8 ppid:     2 flags:0x00000000
	Workqueue: writeback wb_workfn (flush-7:0)
	[<c08a3a10>] (__schedule) from [<c08a3d84>] (schedule+0xdc/0x134)
	[<c08a3d84>] (schedule) from [<c08a65a0>] (rt_mutex_slowlock_block.constprop.0+0xb8/0x174)
	[<c08a65a0>] (rt_mutex_slowlock_block.constprop.0) from [<c08a6708>]
	+(rt_mutex_slowlock.constprop.0+0xac/0x174)
	[<c08a6708>] (rt_mutex_slowlock.constprop.0) from [<c0374d60>] (fat_write_inode+0x34/0x54)
	[<c0374d60>] (fat_write_inode) from [<c0297304>] (__writeback_single_inode+0x354/0x3ec)
	[<c0297304>] (__writeback_single_inode) from [<c0297998>] (writeback_sb_inodes+0x250/0x45c)
	[<c0297998>] (writeback_sb_inodes) from [<c0297c20>] (__writeback_inodes_wb+0x7c/0xb8)
	[<c0297c20>] (__writeback_inodes_wb) from [<c0297f24>] (wb_writeback+0x2c8/0x2e4)
	[<c0297f24>] (wb_writeback) from [<c0298c40>] (wb_workfn+0x1a4/0x3e4)
	[<c0298c40>] (wb_workfn) from [<c0138ab8>] (process_one_work+0x1fc/0x32c)
	[<c0138ab8>] (process_one_work) from [<c0139120>] (worker_thread+0x22c/0x2d8)
	[<c0139120>] (worker_thread) from [<c013e6e0>] (kthread+0x16c/0x178)
	[<c013e6e0>] (kthread) from [<c01000fc>] (ret_from_fork+0x14/0x38)
	Exception stack(0xc10e3fb0 to 0xc10e3ff8)
	3fa0:                                     00000000 00000000 00000000 00000000
	3fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
	3fe0: 00000000 00000000 00000000 00000000 00000013 00000000

	INFO: task tar:2083 blocked for more than 491 seconds.
	      Not tainted 5.15.49-rt46 #1
	"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
	task:tar             state:D stack:    0 pid: 2083 ppid:  2082 flags:0x00000000
	[<c08a3a10>] (__schedule) from [<c08a3d84>] (schedule+0xdc/0x134)
	[<c08a3d84>] (schedule) from [<c08a41b0>] (io_schedule+0x14/0x24)
	[<c08a41b0>] (io_schedule) from [<c08a455c>] (bit_wait_io+0xc/0x30)
	[<c08a455c>] (bit_wait_io) from [<c08a441c>] (__wait_on_bit_lock+0x54/0xa8)
	[<c08a441c>] (__wait_on_bit_lock) from [<c08a44f4>] (out_of_line_wait_on_bit_lock+0x84/0xb0)
	[<c08a44f4>] (out_of_line_wait_on_bit_lock) from [<c0371fb0>] (fat_mirror_bhs+0xa0/0x144)
	[<c0371fb0>] (fat_mirror_bhs) from [<c0372a68>] (fat_alloc_clusters+0x138/0x2a4)
	[<c0372a68>] (fat_alloc_clusters) from [<c0370b14>] (fat_alloc_new_dir+0x34/0x250)
	[<c0370b14>] (fat_alloc_new_dir) from [<c03787c0>] (vfat_mkdir+0x58/0x148)
	[<c03787c0>] (vfat_mkdir) from [<c0277b60>] (vfs_mkdir+0x68/0x98)
	[<c0277b60>] (vfs_mkdir) from [<c027b484>] (do_mkdirat+0xb0/0xec)
	[<c027b484>] (do_mkdirat) from [<c0100060>] (ret_fast_syscall+0x0/0x1c)
	Exception stack(0xc2e1bfa8 to 0xc2e1bff0)
	bfa0:                   01ee42f0 01ee4208 01ee42f0 000041ed 00000000 00004000
	bfc0: 01ee42f0 01ee4208 00000000 00000027 01ee4302 00000004 000dcb00 01ee4190
	bfe0: 000dc368 bed11924 0006d4b0 b6ebddfc

Here the kworker is waiting on msdos_sb_info::s_lock which is held by
tar which is in turn waiting for a buffer which is locked waiting to be
flushed, but this operation is plugged in the kworker.

The lock is a normal struct mutex, so tsk_is_pi_blocked() will always
return false on !RT and thus the behaviour changes for RT.

It seems that the intent here is to skip blk_flush_plug() in the case
where a non-preemptible lock (such as a spinlock) has been converted to
a rtmutex on RT, which is the case covered by the SM_RTLOCK_WAIT
schedule flag.  But sched_submit_work() is only called from schedule()
which is never called in this scenario, so the check can simply be
deleted.

Looking at the history of the -rt patchset, in fact this change was
present from v5.9.1-rt20 until being dropped in v5.13-rt1 as it was part
of a larger patch [1] most of which was replaced by commit b4bfa3fcfe
("sched/core: Rework the __schedule() preempt argument").

As described in [1]:

   The schedule process must distinguish between blocking on a regular
   sleeping lock (rwsem and mutex) and a RT-only sleeping lock (spinlock
   and rwlock):
   - rwsem and mutex must flush block requests (blk_schedule_flush_plug())
     even if blocked on a lock. This can not deadlock because this also
     happens for non-RT.
     There should be a warning if the scheduling point is within a RCU read
     section.

   - spinlock and rwlock must not flush block requests. This will deadlock
     if the callback attempts to acquire a lock which is already acquired.
     Similarly to being preempted, there should be no warning if the
     scheduling point is within a RCU read section.

and with the tsk_is_pi_blocked() in the scheduler path, we hit the first
issue.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/tree/patches/0022-locking-rtmutex-Use-custom-scheduling-function-for-s.patch?h=linux-5.10.y-rt-patches

Signed-off-by: John Keeping <john@metanate.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lkml.kernel.org/r/20220708162702.1758865-1-john@metanate.com
2022-07-13 11:29:17 +02:00
Oleg Nesterov
d5b36a4dbd fix race between exit_itimers() and /proc/pid/timers
As Chris explains, the comment above exit_itimers() is not correct,
we can race with proc_timers_seq_ops. Change exit_itimers() to clear
signal->posix_timers with ->siglock held.

Cc: <stable@vger.kernel.org>
Reported-by: chris@accessvector.net
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-07-11 09:52:59 -07:00
Matthew Rosato
3c5a1b6f0a KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding
These routines will be wired into a kvm ioctl in order to respond to
requests to enable / disable a device for Adapter Event Notifications /
Adapter Interuption Forwarding.

Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Acked-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20220606203325.110625-16-mjrosato@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
2022-07-11 09:54:32 +02:00
Chen Yu
70fb5ccf2e sched/fair: Introduce SIS_UTIL to search idle CPU based on sum of util_avg
[Problem Statement]
select_idle_cpu() might spend too much time searching for an idle CPU,
when the system is overloaded.

The following histogram is the time spent in select_idle_cpu(),
when running 224 instances of netperf on a system with 112 CPUs
per LLC domain:

@usecs:
[0]                  533 |                                                    |
[1]                 5495 |                                                    |
[2, 4)             12008 |                                                    |
[4, 8)            239252 |                                                    |
[8, 16)          4041924 |@@@@@@@@@@@@@@                                      |
[16, 32)        12357398 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@         |
[32, 64)        14820255 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[64, 128)       13047682 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@       |
[128, 256)       8235013 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@                        |
[256, 512)       4507667 |@@@@@@@@@@@@@@@                                     |
[512, 1K)        2600472 |@@@@@@@@@                                           |
[1K, 2K)          927912 |@@@                                                 |
[2K, 4K)          218720 |                                                    |
[4K, 8K)           98161 |                                                    |
[8K, 16K)          37722 |                                                    |
[16K, 32K)          6715 |                                                    |
[32K, 64K)           477 |                                                    |
[64K, 128K)            7 |                                                    |

netperf latency usecs:
=======
case            	load    	    Lat_99th	    std%
TCP_RR          	thread-224	      257.39	(  0.21)

The time spent in select_idle_cpu() is visible to netperf and might have a negative
impact.

[Symptom analysis]
The patch [1] from Mel Gorman has been applied to track the efficiency
of select_idle_sibling. Copy the indicators here:

SIS Search Efficiency(se_eff%):
        A ratio expressed as a percentage of runqueues scanned versus
        idle CPUs found. A 100% efficiency indicates that the target,
        prev or recent CPU of a task was idle at wakeup. The lower the
        efficiency, the more runqueues were scanned before an idle CPU
        was found.

SIS Domain Search Efficiency(dom_eff%):
        Similar, except only for the slower SIS
	patch.

SIS Fast Success Rate(fast_rate%):
        Percentage of SIS that used target, prev or
	recent CPUs.

SIS Success rate(success_rate%):
        Percentage of scans that found an idle CPU.

The test is based on Aubrey's schedtests tool, including netperf, hackbench,
schbench and tbench.

Test on vanilla kernel:
schedstat_parse.py -f netperf_vanilla.log
case	        load	    se_eff%	    dom_eff%	  fast_rate%	success_rate%
TCP_RR	   28 threads	     99.978	      18.535	      99.995	     100.000
TCP_RR	   56 threads	     99.397	       5.671	      99.964	     100.000
TCP_RR	   84 threads	     21.721	       6.818	      73.632	     100.000
TCP_RR	  112 threads	     12.500	       5.533	      59.000	     100.000
TCP_RR	  140 threads	      8.524	       4.535	      49.020	     100.000
TCP_RR	  168 threads	      6.438	       3.945	      40.309	      99.999
TCP_RR	  196 threads	      5.397	       3.718	      32.320	      99.982
TCP_RR	  224 threads	      4.874	       3.661	      25.775	      99.767
UDP_RR	   28 threads	     99.988	      17.704	      99.997	     100.000
UDP_RR	   56 threads	     99.528	       5.977	      99.970	     100.000
UDP_RR	   84 threads	     24.219	       6.992	      76.479	     100.000
UDP_RR	  112 threads	     13.907	       5.706	      62.538	     100.000
UDP_RR	  140 threads	      9.408	       4.699	      52.519	     100.000
UDP_RR	  168 threads	      7.095	       4.077	      44.352	     100.000
UDP_RR	  196 threads	      5.757	       3.775	      35.764	      99.991
UDP_RR	  224 threads	      5.124	       3.704	      28.748	      99.860

schedstat_parse.py -f schbench_vanilla.log
(each group has 28 tasks)
case	        load	    se_eff%	    dom_eff%	  fast_rate%	success_rate%
normal	   1   mthread	     99.152	       6.400	      99.941	     100.000
normal	   2   mthreads	     97.844	       4.003	      99.908	     100.000
normal	   3   mthreads	     96.395	       2.118	      99.917	      99.998
normal	   4   mthreads	     55.288	       1.451	      98.615	      99.804
normal	   5   mthreads	      7.004	       1.870	      45.597	      61.036
normal	   6   mthreads	      3.354	       1.346	      20.777	      34.230
normal	   7   mthreads	      2.183	       1.028	      11.257	      21.055
normal	   8   mthreads	      1.653	       0.825	       7.849	      15.549

schedstat_parse.py -f hackbench_vanilla.log
(each group has 28 tasks)
case			load	        se_eff%	    dom_eff%	  fast_rate%	success_rate%
process-pipe	     1 group	         99.991	       7.692	      99.999	     100.000
process-pipe	    2 groups	         99.934	       4.615	      99.997	     100.000
process-pipe	    3 groups	         99.597	       3.198	      99.987	     100.000
process-pipe	    4 groups	         98.378	       2.464	      99.958	     100.000
process-pipe	    5 groups	         27.474	       3.653	      89.811	      99.800
process-pipe	    6 groups	         20.201	       4.098	      82.763	      99.570
process-pipe	    7 groups	         16.423	       4.156	      77.398	      99.316
process-pipe	    8 groups	         13.165	       3.920	      72.232	      98.828
process-sockets	     1 group	         99.977	       5.882	      99.999	     100.000
process-sockets	    2 groups	         99.927	       5.505	      99.996	     100.000
process-sockets	    3 groups	         99.397	       3.250	      99.980	     100.000
process-sockets	    4 groups	         79.680	       4.258	      98.864	      99.998
process-sockets	    5 groups	          7.673	       2.503	      63.659	      92.115
process-sockets	    6 groups	          4.642	       1.584	      58.946	      88.048
process-sockets	    7 groups	          3.493	       1.379	      49.816	      81.164
process-sockets	    8 groups	          3.015	       1.407	      40.845	      75.500
threads-pipe	     1 group	         99.997	       0.000	     100.000	     100.000
threads-pipe	    2 groups	         99.894	       2.932	      99.997	     100.000
threads-pipe	    3 groups	         99.611	       4.117	      99.983	     100.000
threads-pipe	    4 groups	         97.703	       2.624	      99.937	     100.000
threads-pipe	    5 groups	         22.919	       3.623	      87.150	      99.764
threads-pipe	    6 groups	         18.016	       4.038	      80.491	      99.557
threads-pipe	    7 groups	         14.663	       3.991	      75.239	      99.247
threads-pipe	    8 groups	         12.242	       3.808	      70.651	      98.644
threads-sockets	     1 group	         99.990	       6.667	      99.999	     100.000
threads-sockets	    2 groups	         99.940	       5.114	      99.997	     100.000
threads-sockets	    3 groups	         99.469	       4.115	      99.977	     100.000
threads-sockets	    4 groups	         87.528	       4.038	      99.400	     100.000
threads-sockets	    5 groups	          6.942	       2.398	      59.244	      88.337
threads-sockets	    6 groups	          4.359	       1.954	      49.448	      87.860
threads-sockets	    7 groups	          2.845	       1.345	      41.198	      77.102
threads-sockets	    8 groups	          2.871	       1.404	      38.512	      74.312

schedstat_parse.py -f tbench_vanilla.log
case			load	      se_eff%	    dom_eff%	  fast_rate%	success_rate%
loopback	  28 threads	       99.976	      18.369	      99.995	     100.000
loopback	  56 threads	       99.222	       7.799	      99.934	     100.000
loopback	  84 threads	       19.723	       6.819	      70.215	     100.000
loopback	 112 threads	       11.283	       5.371	      55.371	      99.999
loopback	 140 threads	        0.000	       0.000	       0.000	       0.000
loopback	 168 threads	        0.000	       0.000	       0.000	       0.000
loopback	 196 threads	        0.000	       0.000	       0.000	       0.000
loopback	 224 threads	        0.000	       0.000	       0.000	       0.000

According to the test above, if the system becomes busy, the
SIS Search Efficiency(se_eff%) drops significantly. Although some
benchmarks would finally find an idle CPU(success_rate% = 100%), it is
doubtful whether it is worth it to search the whole LLC domain.

[Proposal]
It would be ideal to have a crystal ball to answer this question:
How many CPUs must a wakeup path walk down, before it can find an idle
CPU? Many potential metrics could be used to predict the number.
One candidate is the sum of util_avg in this LLC domain. The benefit
of choosing util_avg is that it is a metric of accumulated historic
activity, which seems to be smoother than instantaneous metrics
(such as rq->nr_running). Besides, choosing the sum of util_avg
would help predict the load of the LLC domain more precisely, because
SIS_PROP uses one CPU's idle time to estimate the total LLC domain idle
time.

In summary, the lower the util_avg is, the more select_idle_cpu()
should scan for idle CPU, and vice versa. When the sum of util_avg
in this LLC domain hits 85% or above, the scan stops. The reason to
choose 85% as the threshold is that this is the imbalance_pct(117)
when a LLC sched group is overloaded.

Introduce the quadratic function:

y = SCHED_CAPACITY_SCALE - p * x^2
and y'= y / SCHED_CAPACITY_SCALE

x is the ratio of sum_util compared to the CPU capacity:
x = sum_util / (llc_weight * SCHED_CAPACITY_SCALE)
y' is the ratio of CPUs to be scanned in the LLC domain,
and the number of CPUs to scan is calculated by:

nr_scan = llc_weight * y'

Choosing quadratic function is because:
[1] Compared to the linear function, it scans more aggressively when the
    sum_util is low.
[2] Compared to the exponential function, it is easier to calculate.
[3] It seems that there is no accurate mapping between the sum of util_avg
    and the number of CPUs to be scanned. Use heuristic scan for now.

For a platform with 112 CPUs per LLC, the number of CPUs to scan is:
sum_util%   0    5   15   25  35  45  55   65   75   85   86 ...
scan_nr   112  111  108  102  93  81  65   47   25    1    0 ...

For a platform with 16 CPUs per LLC, the number of CPUs to scan is:
sum_util%   0    5   15   25  35  45  55   65   75   85   86 ...
scan_nr    16   15   15   14  13  11   9    6    3    0    0 ...

Furthermore, to minimize the overhead of calculating the metrics in
select_idle_cpu(), borrow the statistics from periodic load balance.
As mentioned by Abel, on a platform with 112 CPUs per LLC, the
sum_util calculated by periodic load balance after 112 ms would
decay to about 0.5 * 0.5 * 0.5 * 0.7 = 8.75%, thus bringing a delay
in reflecting the latest utilization. But it is a trade-off.
Checking the util_avg in newidle load balance would be more frequent,
but it brings overhead - multiple CPUs write/read the per-LLC shared
variable and introduces cache contention. Tim also mentioned that,
it is allowed to be non-optimal in terms of scheduling for the
short-term variations, but if there is a long-term trend in the load
behavior, the scheduler can adjust for that.

When SIS_UTIL is enabled, the select_idle_cpu() uses the nr_scan
calculated by SIS_UTIL instead of the one from SIS_PROP. As Peter and
Mel suggested, SIS_UTIL should be enabled by default.

This patch is based on the util_avg, which is very sensitive to the
CPU frequency invariance. There is an issue that, when the max frequency
has been clamp, the util_avg would decay insanely fast when
the CPU is idle. Commit addca28512 ("cpufreq: intel_pstate: Handle no_turbo
in frequency invariance") could be used to mitigate this symptom, by adjusting
the arch_max_freq_ratio when turbo is disabled. But this issue is still
not thoroughly fixed, because the current code is unaware of the user-specified
max CPU frequency.

[Test result]

netperf and tbench were launched with 25% 50% 75% 100% 125% 150%
175% 200% of CPU number respectively. Hackbench and schbench were launched
by 1, 2 ,4, 8 groups. Each test lasts for 100 seconds and repeats 3 times.

The following is the benchmark result comparison between
baseline:vanilla v5.19-rc1 and compare:patched kernel. Positive compare%
indicates better performance.

Each netperf test is a:
netperf -4 -H 127.0.1 -t TCP/UDP_RR -c -C -l 100
netperf.throughput
=======
case            	load    	baseline(std%)	compare%( std%)
TCP_RR          	28 threads	 1.00 (  0.34)	 -0.16 (  0.40)
TCP_RR          	56 threads	 1.00 (  0.19)	 -0.02 (  0.20)
TCP_RR          	84 threads	 1.00 (  0.39)	 -0.47 (  0.40)
TCP_RR          	112 threads	 1.00 (  0.21)	 -0.66 (  0.22)
TCP_RR          	140 threads	 1.00 (  0.19)	 -0.69 (  0.19)
TCP_RR          	168 threads	 1.00 (  0.18)	 -0.48 (  0.18)
TCP_RR          	196 threads	 1.00 (  0.16)	+194.70 ( 16.43)
TCP_RR          	224 threads	 1.00 (  0.16)	+197.30 (  7.85)
UDP_RR          	28 threads	 1.00 (  0.37)	 +0.35 (  0.33)
UDP_RR          	56 threads	 1.00 ( 11.18)	 -0.32 (  0.21)
UDP_RR          	84 threads	 1.00 (  1.46)	 -0.98 (  0.32)
UDP_RR          	112 threads	 1.00 ( 28.85)	 -2.48 ( 19.61)
UDP_RR          	140 threads	 1.00 (  0.70)	 -0.71 ( 14.04)
UDP_RR          	168 threads	 1.00 ( 14.33)	 -0.26 ( 11.16)
UDP_RR          	196 threads	 1.00 ( 12.92)	+186.92 ( 20.93)
UDP_RR          	224 threads	 1.00 ( 11.74)	+196.79 ( 18.62)

Take the 224 threads as an example, the SIS search metrics changes are
illustrated below:

    vanilla                    patched
   4544492          +237.5%   15338634        sched_debug.cpu.sis_domain_search.avg
     38539        +39686.8%   15333634        sched_debug.cpu.sis_failed.avg
  128300000          -87.9%   15551326        sched_debug.cpu.sis_scanned.avg
   5842896          +162.7%   15347978        sched_debug.cpu.sis_search.avg

There is -87.9% less CPU scans after patched, which indicates lower overhead.
Besides, with this patch applied, there is -13% less rq lock contention
in perf-profile.calltrace.cycles-pp._raw_spin_lock.raw_spin_rq_lock_nested
.try_to_wake_up.default_wake_function.woken_wake_function.
This might help explain the performance improvement - Because this patch allows
the waking task to remain on the previous CPU, rather than grabbing other CPUs'
lock.

Each hackbench test is a:
hackbench -g $job --process/threads --pipe/sockets -l 1000000 -s 100
hackbench.throughput
=========
case            	load    	baseline(std%)	compare%( std%)
process-pipe    	1 group 	 1.00 (  1.29)	 +0.57 (  0.47)
process-pipe    	2 groups 	 1.00 (  0.27)	 +0.77 (  0.81)
process-pipe    	4 groups 	 1.00 (  0.26)	 +1.17 (  0.02)
process-pipe    	8 groups 	 1.00 (  0.15)	 -4.79 (  0.02)
process-sockets 	1 group 	 1.00 (  0.63)	 -0.92 (  0.13)
process-sockets 	2 groups 	 1.00 (  0.03)	 -0.83 (  0.14)
process-sockets 	4 groups 	 1.00 (  0.40)	 +5.20 (  0.26)
process-sockets 	8 groups 	 1.00 (  0.04)	 +3.52 (  0.03)
threads-pipe    	1 group 	 1.00 (  1.28)	 +0.07 (  0.14)
threads-pipe    	2 groups 	 1.00 (  0.22)	 -0.49 (  0.74)
threads-pipe    	4 groups 	 1.00 (  0.05)	 +1.88 (  0.13)
threads-pipe    	8 groups 	 1.00 (  0.09)	 -4.90 (  0.06)
threads-sockets 	1 group 	 1.00 (  0.25)	 -0.70 (  0.53)
threads-sockets 	2 groups 	 1.00 (  0.10)	 -0.63 (  0.26)
threads-sockets 	4 groups 	 1.00 (  0.19)	+11.92 (  0.24)
threads-sockets 	8 groups 	 1.00 (  0.08)	 +4.31 (  0.11)

Each tbench test is a:
tbench -t 100 $job 127.0.0.1
tbench.throughput
======
case            	load    	baseline(std%)	compare%( std%)
loopback        	28 threads	 1.00 (  0.06)	 -0.14 (  0.09)
loopback        	56 threads	 1.00 (  0.03)	 -0.04 (  0.17)
loopback        	84 threads	 1.00 (  0.05)	 +0.36 (  0.13)
loopback        	112 threads	 1.00 (  0.03)	 +0.51 (  0.03)
loopback        	140 threads	 1.00 (  0.02)	 -1.67 (  0.19)
loopback        	168 threads	 1.00 (  0.38)	 +1.27 (  0.27)
loopback        	196 threads	 1.00 (  0.11)	 +1.34 (  0.17)
loopback        	224 threads	 1.00 (  0.11)	 +1.67 (  0.22)

Each schbench test is a:
schbench -m $job -t 28 -r 100 -s 30000 -c 30000
schbench.latency_90%_us
========
case            	load    	baseline(std%)	compare%( std%)
normal          	1 mthread	 1.00 ( 31.22)	 -7.36 ( 20.25)*
normal          	2 mthreads	 1.00 (  2.45)	 -0.48 (  1.79)
normal          	4 mthreads	 1.00 (  1.69)	 +0.45 (  0.64)
normal          	8 mthreads	 1.00 (  5.47)	 +9.81 ( 14.28)

*Consider the Standard Deviation, this -7.36% regression might not be valid.

Also, a OLTP workload with a commercial RDBMS has been tested, and there
is no significant change.

There were concerns that unbalanced tasks among CPUs would cause problems.
For example, suppose the LLC domain is composed of 8 CPUs, and 7 tasks are
bound to CPU0~CPU6, while CPU7 is idle:

          CPU0    CPU1    CPU2    CPU3    CPU4    CPU5    CPU6    CPU7
util_avg  1024    1024    1024    1024    1024    1024    1024    0

Since the util_avg ratio is 87.5%( = 7/8 ), which is higher than 85%,
select_idle_cpu() will not scan, thus CPU7 is undetected during scan.
But according to Mel, it is unlikely the CPU7 will be idle all the time
because CPU7 could pull some tasks via CPU_NEWLY_IDLE.

lkp(kernel test robot) has reported a regression on stress-ng.sock on a
very busy system. According to the sched_debug statistics, it might be caused
by SIS_UTIL terminates the scan and chooses a previous CPU earlier, and this
might introduce more context switch, especially involuntary preemption, which
impacts a busy stress-ng. This regression has shown that, not all benchmarks
in every scenario benefit from idle CPU scan limit, and it needs further
investigation.

Besides, there is slight regression in hackbench's 16 groups case when the
LLC domain has 16 CPUs. Prateek mentioned that we should scan aggressively
in an LLC domain with 16 CPUs. Because the cost to search for an idle one
among 16 CPUs is negligible. The current patch aims to propose a generic
solution and only considers the util_avg. Something like the below could
be applied on top of the current patch to fulfill the requirement:

	if (llc_weight <= 16)
		nr_scan = nr_scan * 32 / llc_weight;

For LLC domain with 16 CPUs, the nr_scan will be expanded to 2 times large.
The smaller the CPU number this LLC domain has, the larger nr_scan will be
expanded. This needs further investigation.

There is also ongoing work[2] from Abel to filter out the busy CPUs during
wakeup, to further speed up the idle CPU scan. And it could be a following-up
optimization on top of this change.

Suggested-by: Tim Chen <tim.c.chen@intel.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Yicong Yang <yangyicong@hisilicon.com>
Tested-by: Mohini Narkhede <mohini.narkhede@intel.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20220612163428.849378-1-yu.c.chen@intel.com
2022-06-28 09:08:30 +02:00
Mike Rapoport
ee65728e10 docs: rename Documentation/vm to Documentation/mm
so it will be consistent with code mm directory and with
Documentation/admin-guide/mm and won't be confused with virtual machines.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Tested-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Acked-by: Wu XiangCheng <bobwxc@email.cn>
2022-06-27 12:52:53 -07:00
Linus Torvalds
67850b7bdc While looking at the ptrace problems with PREEMPT_RT and the problems
of Peter Zijlstra was encountering with ptrace in his freezer rewrite
 I identified some cleanups to ptrace_stop that make sense on their own
 and move make resolving the other problems much simpler.
 
 The biggest issue is the habbit of the ptrace code to change task->__state
 from the tracer to suppress TASK_WAKEKILL from waking up the tracee.  No
 other code in the kernel does that and it is straight forward to update
 signal_wake_up and friends to make that unnecessary.
 
 Peter's task freezer sets frozen tasks to a new state TASK_FROZEN and
 then it stores them by calling "wake_up_state(t, TASK_FROZEN)" relying
 on the fact that all stopped states except the special stop states can
 tolerate spurious wake up and recover their state.
 
 The state of stopped and traced tasked is changed to be stored in
 task->jobctl as well as in task->__state.  This makes it possible for
 the freezer to recover tasks in these special states, as well as
 serving as a general cleanup.  With a little more work in that
 direction I believe TASK_STOPPED can learn to tolerate spurious wake
 ups and become an ordinary stop state.
 
 The TASK_TRACED state has to remain a special state as the registers for
 a process are only reliably available when the process is stopped in
 the scheduler.  Fundamentally ptrace needs acess to the saved
 register values of a task.
 
 There are bunch of semi-random ptrace related cleanups that were found
 while looking at these issues.
 
 One cleanup that deserves to be called out is from commit 57b6de08b5
 ("ptrace: Admit ptrace_stop can generate spuriuos SIGTRAPs").  This
 makes a change that is technically user space visible, in the handling
 of what happens to a tracee when a tracer dies unexpectedly.
 According to our testing and our understanding of userspace nothing
 cares that spurious SIGTRAPs can be generated in that case.
 
 The entire discussion can be found at:
   https://lkml.kernel.org/r/87a6bv6dl6.fsf_-_@email.froward.int.ebiederm.org
 
 Eric W. Biederman (11):
       signal: Rename send_signal send_signal_locked
       signal: Replace __group_send_sig_info with send_signal_locked
       ptrace/um: Replace PT_DTRACE with TIF_SINGLESTEP
       ptrace/xtensa: Replace PT_SINGLESTEP with TIF_SINGLESTEP
       ptrace: Remove arch_ptrace_attach
       signal: Use lockdep_assert_held instead of assert_spin_locked
       ptrace: Reimplement PTRACE_KILL by always sending SIGKILL
       ptrace: Document that wait_task_inactive can't fail
       ptrace: Admit ptrace_stop can generate spuriuos SIGTRAPs
       ptrace: Don't change __state
       ptrace: Always take siglock in ptrace_resume
 
 Peter Zijlstra (1):
       sched,signal,ptrace: Rework TASK_TRACED, TASK_STOPPED state
 
  arch/ia64/include/asm/ptrace.h    |   4 --
  arch/ia64/kernel/ptrace.c         |  57 ----------------
  arch/um/include/asm/thread_info.h |   2 +
  arch/um/kernel/exec.c             |   2 +-
  arch/um/kernel/process.c          |   2 +-
  arch/um/kernel/ptrace.c           |   8 +--
  arch/um/kernel/signal.c           |   4 +-
  arch/x86/kernel/step.c            |   3 +-
  arch/xtensa/kernel/ptrace.c       |   4 +-
  arch/xtensa/kernel/signal.c       |   4 +-
  drivers/tty/tty_jobctrl.c         |   4 +-
  include/linux/ptrace.h            |   7 --
  include/linux/sched.h             |  10 ++-
  include/linux/sched/jobctl.h      |   8 +++
  include/linux/sched/signal.h      |  20 ++++--
  include/linux/signal.h            |   3 +-
  kernel/ptrace.c                   |  87 ++++++++---------------
  kernel/sched/core.c               |   5 +-
  kernel/signal.c                   | 140 +++++++++++++++++---------------------
  kernel/time/posix-cpu-timers.c    |   6 +-
  20 files changed, 140 insertions(+), 240 deletions(-)
 
 Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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Merge tag 'ptrace_stop-cleanup-for-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

Pull ptrace_stop cleanups from Eric Biederman:
 "While looking at the ptrace problems with PREEMPT_RT and the problems
  Peter Zijlstra was encountering with ptrace in his freezer rewrite I
  identified some cleanups to ptrace_stop that make sense on their own
  and move make resolving the other problems much simpler.

  The biggest issue is the habit of the ptrace code to change
  task->__state from the tracer to suppress TASK_WAKEKILL from waking up
  the tracee. No other code in the kernel does that and it is straight
  forward to update signal_wake_up and friends to make that unnecessary.

  Peter's task freezer sets frozen tasks to a new state TASK_FROZEN and
  then it stores them by calling "wake_up_state(t, TASK_FROZEN)" relying
  on the fact that all stopped states except the special stop states can
  tolerate spurious wake up and recover their state.

  The state of stopped and traced tasked is changed to be stored in
  task->jobctl as well as in task->__state. This makes it possible for
  the freezer to recover tasks in these special states, as well as
  serving as a general cleanup. With a little more work in that
  direction I believe TASK_STOPPED can learn to tolerate spurious wake
  ups and become an ordinary stop state.

  The TASK_TRACED state has to remain a special state as the registers
  for a process are only reliably available when the process is stopped
  in the scheduler. Fundamentally ptrace needs acess to the saved
  register values of a task.

  There are bunch of semi-random ptrace related cleanups that were found
  while looking at these issues.

  One cleanup that deserves to be called out is from commit 57b6de08b5
  ("ptrace: Admit ptrace_stop can generate spuriuos SIGTRAPs"). This
  makes a change that is technically user space visible, in the handling
  of what happens to a tracee when a tracer dies unexpectedly. According
  to our testing and our understanding of userspace nothing cares that
  spurious SIGTRAPs can be generated in that case"

* tag 'ptrace_stop-cleanup-for-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  sched,signal,ptrace: Rework TASK_TRACED, TASK_STOPPED state
  ptrace: Always take siglock in ptrace_resume
  ptrace: Don't change __state
  ptrace: Admit ptrace_stop can generate spuriuos SIGTRAPs
  ptrace: Document that wait_task_inactive can't fail
  ptrace: Reimplement PTRACE_KILL by always sending SIGKILL
  signal: Use lockdep_assert_held instead of assert_spin_locked
  ptrace: Remove arch_ptrace_attach
  ptrace/xtensa: Replace PT_SINGLESTEP with TIF_SINGLESTEP
  ptrace/um: Replace PT_DTRACE with TIF_SINGLESTEP
  signal: Replace __group_send_sig_info with send_signal_locked
  signal: Rename send_signal send_signal_locked
2022-06-03 16:13:25 -07:00
Linus Torvalds
1ec6574a3c This set of changes updates init and user mode helper tasks to be
ordinary user mode tasks.
 
 In commit 40966e316f ("kthread: Ensure struct kthread is present for
 all kthreads") caused init and the user mode helper threads that call
 kernel_execve to have struct kthread allocated for them.  This struct
 kthread going away during execve in turned made a use after free of
 struct kthread possible.
 
 The commit 343f4c49f2 ("kthread: Don't allocate kthread_struct for
 init and umh") is enough to fix the use after free and is simple enough
 to be backportable.
 
 The rest of the changes pass struct kernel_clone_args to clean things
 up and cause the code to make sense.
 
 In making init and the user mode helpers tasks purely user mode tasks
 I ran into two complications.  The function task_tick_numa was
 detecting tasks without an mm by testing for the presence of
 PF_KTHREAD.  The initramfs code in populate_initrd_image was using
 flush_delayed_fput to ensuere the closing of all it's file descriptors
 was complete, and flush_delayed_fput does not work in a userspace thread.
 
 I have looked and looked and more complications and in my code review
 I have not found any, and neither has anyone else with the code sitting
 in linux-next.
 
 Link: https://lkml.kernel.org/r/87mtfu4up3.fsf@email.froward.int.ebiederm.org
 
 Eric W. Biederman (8):
       kthread: Don't allocate kthread_struct for init and umh
       fork: Pass struct kernel_clone_args into copy_thread
       fork: Explicity test for idle tasks in copy_thread
       fork: Generalize PF_IO_WORKER handling
       init: Deal with the init process being a user mode process
       fork: Explicitly set PF_KTHREAD
       fork: Stop allowing kthreads to call execve
       sched: Update task_tick_numa to ignore tasks without an mm
 
  arch/alpha/kernel/process.c      | 13 ++++++------
  arch/arc/kernel/process.c        | 13 ++++++------
  arch/arm/kernel/process.c        | 12 ++++++-----
  arch/arm64/kernel/process.c      | 12 ++++++-----
  arch/csky/kernel/process.c       | 15 ++++++-------
  arch/h8300/kernel/process.c      | 10 ++++-----
  arch/hexagon/kernel/process.c    | 12 ++++++-----
  arch/ia64/kernel/process.c       | 15 +++++++------
  arch/m68k/kernel/process.c       | 12 ++++++-----
  arch/microblaze/kernel/process.c | 12 ++++++-----
  arch/mips/kernel/process.c       | 13 ++++++------
  arch/nios2/kernel/process.c      | 12 ++++++-----
  arch/openrisc/kernel/process.c   | 12 ++++++-----
  arch/parisc/kernel/process.c     | 18 +++++++++-------
  arch/powerpc/kernel/process.c    | 15 +++++++------
  arch/riscv/kernel/process.c      | 12 ++++++-----
  arch/s390/kernel/process.c       | 12 ++++++-----
  arch/sh/kernel/process_32.c      | 12 ++++++-----
  arch/sparc/kernel/process_32.c   | 12 ++++++-----
  arch/sparc/kernel/process_64.c   | 12 ++++++-----
  arch/um/kernel/process.c         | 15 +++++++------
  arch/x86/include/asm/fpu/sched.h |  2 +-
  arch/x86/include/asm/switch_to.h |  8 +++----
  arch/x86/kernel/fpu/core.c       |  4 ++--
  arch/x86/kernel/process.c        | 18 +++++++++-------
  arch/xtensa/kernel/process.c     | 17 ++++++++-------
  fs/exec.c                        |  8 ++++---
  include/linux/sched/task.h       |  8 +++++--
  init/initramfs.c                 |  2 ++
  init/main.c                      |  2 +-
  kernel/fork.c                    | 46 +++++++++++++++++++++++++++++++++-------
  kernel/sched/fair.c              |  2 +-
  kernel/umh.c                     |  6 +++---
  33 files changed, 234 insertions(+), 160 deletions(-)
 
 Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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Merge tag 'kthread-cleanups-for-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

Pull kthread updates from Eric Biederman:
 "This updates init and user mode helper tasks to be ordinary user mode
  tasks.

  Commit 40966e316f ("kthread: Ensure struct kthread is present for
  all kthreads") caused init and the user mode helper threads that call
  kernel_execve to have struct kthread allocated for them. This struct
  kthread going away during execve in turned made a use after free of
  struct kthread possible.

  Here, commit 343f4c49f2 ("kthread: Don't allocate kthread_struct for
  init and umh") is enough to fix the use after free and is simple
  enough to be backportable.

  The rest of the changes pass struct kernel_clone_args to clean things
  up and cause the code to make sense.

  In making init and the user mode helpers tasks purely user mode tasks
  I ran into two complications. The function task_tick_numa was
  detecting tasks without an mm by testing for the presence of
  PF_KTHREAD. The initramfs code in populate_initrd_image was using
  flush_delayed_fput to ensuere the closing of all it's file descriptors
  was complete, and flush_delayed_fput does not work in a userspace
  thread.

  I have looked and looked and more complications and in my code review
  I have not found any, and neither has anyone else with the code
  sitting in linux-next"

* tag 'kthread-cleanups-for-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  sched: Update task_tick_numa to ignore tasks without an mm
  fork: Stop allowing kthreads to call execve
  fork: Explicitly set PF_KTHREAD
  init: Deal with the init process being a user mode process
  fork: Generalize PF_IO_WORKER handling
  fork: Explicity test for idle tasks in copy_thread
  fork: Pass struct kernel_clone_args into copy_thread
  kthread: Don't allocate kthread_struct for init and umh
2022-06-03 16:03:05 -07:00
Linus Torvalds
6112bd00e8 powerpc updates for 5.19
- Convert to the generic mmap support (ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT).
 
  - Add support for outline-only KASAN with 64-bit Radix MMU (P9 or later).
 
  - Increase SIGSTKSZ and MINSIGSTKSZ and add support for AT_MINSIGSTKSZ.
 
  - Enable the DAWR (Data Address Watchpoint) on POWER9 DD2.3 or later.
 
  - Drop support for system call instruction emulation.
 
  - Many other small features and fixes.
 
 Thanks to: Alexey Kardashevskiy, Alistair Popple, Andy Shevchenko, Bagas Sanjaya, Bjorn
 Helgaas, Bo Liu, Chen Huang, Christophe Leroy, Colin Ian King, Daniel Axtens, Dwaipayan
 Ray, Fabiano Rosas, Finn Thain, Frank Rowand, Fuqian Huang, Guilherme G. Piccoli, Hangyu
 Hua, Haowen Bai, Haren Myneni, Hari Bathini, He Ying, Jason Wang, Jiapeng Chong, Jing
 Yangyang, Joel Stanley, Julia Lawall, Kajol Jain, Kevin Hao, Krzysztof Kozlowski, Laurent
 Dufour, Lv Ruyi, Madhavan Srinivasan, Magali Lemes, Miaoqian Lin, Minghao Chi, Nathan
 Chancellor, Naveen N. Rao, Nicholas Piggin, Oliver O'Halloran, Oscar Salvador, Pali Rohár,
 Paul Mackerras, Peng Wu, Qing Wang, Randy Dunlap, Reza Arbab, Russell Currey, Sohaib
 Mohamed, Vaibhav Jain, Vasant Hegde, Wang Qing, Wang Wensheng, Xiang wangx, Xiaomeng Tong,
 Xu Wang, Yang Guang, Yang Li, Ye Bin, YueHaibing, Yu Kuai, Zheng Bin, Zou Wei, Zucheng
 Zheng.
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Merge tag 'powerpc-5.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc updates from Michael Ellerman:

 - Convert to the generic mmap support (ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT)

 - Add support for outline-only KASAN with 64-bit Radix MMU (P9 or later)

 - Increase SIGSTKSZ and MINSIGSTKSZ and add support for AT_MINSIGSTKSZ

 - Enable the DAWR (Data Address Watchpoint) on POWER9 DD2.3 or later

 - Drop support for system call instruction emulation

 - Many other small features and fixes

Thanks to Alexey Kardashevskiy, Alistair Popple, Andy Shevchenko, Bagas
Sanjaya, Bjorn Helgaas, Bo Liu, Chen Huang, Christophe Leroy, Colin Ian
King, Daniel Axtens, Dwaipayan Ray, Fabiano Rosas, Finn Thain, Frank
Rowand, Fuqian Huang, Guilherme G. Piccoli, Hangyu Hua, Haowen Bai,
Haren Myneni, Hari Bathini, He Ying, Jason Wang, Jiapeng Chong, Jing
Yangyang, Joel Stanley, Julia Lawall, Kajol Jain, Kevin Hao, Krzysztof
Kozlowski, Laurent Dufour, Lv Ruyi, Madhavan Srinivasan, Magali Lemes,
Miaoqian Lin, Minghao Chi, Nathan Chancellor, Naveen N. Rao, Nicholas
Piggin, Oliver O'Halloran, Oscar Salvador, Pali Rohár, Paul Mackerras,
Peng Wu, Qing Wang, Randy Dunlap, Reza Arbab, Russell Currey, Sohaib
Mohamed, Vaibhav Jain, Vasant Hegde, Wang Qing, Wang Wensheng, Xiang
wangx, Xiaomeng Tong, Xu Wang, Yang Guang, Yang Li, Ye Bin, YueHaibing,
Yu Kuai, Zheng Bin, Zou Wei, and Zucheng Zheng.

* tag 'powerpc-5.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (200 commits)
  powerpc/64: Include cache.h directly in paca.h
  powerpc/64s: Only set HAVE_ARCH_UNMAPPED_AREA when CONFIG_PPC_64S_HASH_MMU is set
  powerpc/xics: Include missing header
  powerpc/powernv/pci: Drop VF MPS fixup
  powerpc/fsl_book3e: Don't set rodata RO too early
  powerpc/microwatt: Add mmu bits to device tree
  powerpc/powernv/flash: Check OPAL flash calls exist before using
  powerpc/powermac: constify device_node in of_irq_parse_oldworld()
  powerpc/powermac: add missing g5_phy_disable_cpu1() declaration
  selftests/powerpc/pmu: fix spelling mistake "mis-match" -> "mismatch"
  powerpc: Enable the DAWR on POWER9 DD2.3 and above
  powerpc/64s: Add CPU_FTRS_POWER10 to ALWAYS mask
  powerpc/64s: Add CPU_FTRS_POWER9_DD2_2 to CPU_FTRS_ALWAYS mask
  powerpc: Fix all occurences of "the the"
  selftests/powerpc/pmu/ebb: remove fixed_instruction.S
  powerpc/platforms/83xx: Use of_device_get_match_data()
  powerpc/eeh: Drop redundant spinlock initialization
  powerpc/iommu: Add missing of_node_put in iommu_init_early_dart
  powerpc/pseries/vas: Call misc_deregister if sysfs init fails
  powerpc/papr_scm: Fix leaking nvdimm_events_map elements
  ...
2022-05-28 11:27:17 -07:00
Linus Torvalds
44d35720c9 sysctl changes for v5.19-rc1
For two kernel releases now kernel/sysctl.c has been being cleaned up
 slowly, since the tables were grossly long, sprinkled with tons of #ifdefs and
 all this caused merge conflicts with one susbystem or another.
 
 This tree was put together to help try to avoid conflicts with these cleanups
 going on different trees at time. So nothing exciting on this pull request,
 just cleanups.
 
 I actually had this sysctl-next tree up since v5.18 but I missed sending a
 pull request for it on time during the last merge window. And so these changes
 have been being soaking up on sysctl-next and so linux-next for a while.
 The last change was merged May 4th.
 
 Most of the compile issues were reported by 0day and fixed.
 
 To help avoid a conflict with bpf folks at Daniel Borkmann's request
 I merged bpf-next/pr/bpf-sysctl into sysctl-next to get the effor which
 moves the BPF sysctls from kernel/sysctl.c to BPF core.
 
 Possible merge conflicts and known resolutions as per linux-next:
 
 bfp:
 https://lkml.kernel.org/r/20220414112812.652190b5@canb.auug.org.au
 
 rcu:
 https://lkml.kernel.org/r/20220420153746.4790d532@canb.auug.org.au
 
 powerpc:
 https://lkml.kernel.org/r/20220520154055.7f964b76@canb.auug.org.au
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Merge tag 'sysctl-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux

Pull sysctl updates from Luis Chamberlain:
 "For two kernel releases now kernel/sysctl.c has been being cleaned up
  slowly, since the tables were grossly long, sprinkled with tons of
  #ifdefs and all this caused merge conflicts with one susbystem or
  another.

  This tree was put together to help try to avoid conflicts with these
  cleanups going on different trees at time. So nothing exciting on this
  pull request, just cleanups.

  Thanks a lot to the Uniontech and Huawei folks for doing some of this
  nasty work"

* tag 'sysctl-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux: (28 commits)
  sched: Fix build warning without CONFIG_SYSCTL
  reboot: Fix build warning without CONFIG_SYSCTL
  kernel/kexec_core: move kexec_core sysctls into its own file
  sysctl: minor cleanup in new_dir()
  ftrace: fix building with SYSCTL=y but DYNAMIC_FTRACE=n
  fs/proc: Introduce list_for_each_table_entry for proc sysctl
  mm: fix unused variable kernel warning when SYSCTL=n
  latencytop: move sysctl to its own file
  ftrace: fix building with SYSCTL=n but DYNAMIC_FTRACE=y
  ftrace: Fix build warning
  ftrace: move sysctl_ftrace_enabled to ftrace.c
  kernel/do_mount_initrd: move real_root_dev sysctls to its own file
  kernel/delayacct: move delayacct sysctls to its own file
  kernel/acct: move acct sysctls to its own file
  kernel/panic: move panic sysctls to its own file
  kernel/lockdep: move lockdep sysctls to its own file
  mm: move page-writeback sysctls to their own file
  mm: move oom_kill sysctls to their own file
  kernel/reboot: move reboot sysctls to its own file
  sched: Move energy_aware sysctls to topology.c
  ...
2022-05-26 16:57:20 -07:00
Linus Torvalds
98931dd95f Yang Shi has improved the behaviour of khugepaged collapsing of readonly
file-backed transparent hugepages.
 
 Johannes Weiner has arranged for zswap memory use to be tracked and
 managed on a per-cgroup basis.
 
 Munchun Song adds a /proc knob ("hugetlb_optimize_vmemmap") for runtime
 enablement of the recent huge page vmemmap optimization feature.
 
 Baolin Wang contributes a series to fix some issues around hugetlb
 pagetable invalidation.
 
 Zhenwei Pi has fixed some interactions between hwpoisoned pages and
 virtualization.
 
 Tong Tiangen has enabled the use of the presently x86-only
 page_table_check debugging feature on arm64 and riscv.
 
 David Vernet has done some fixup work on the memcg selftests.
 
 Peter Xu has taught userfaultfd to handle write protection faults against
 shmem- and hugetlbfs-backed files.
 
 More DAMON development from SeongJae Park - adding online tuning of the
 feature and support for monitoring of fixed virtual address ranges.  Also
 easier discovery of which monitoring operations are available.
 
 Nadav Amit has done some optimization of TLB flushing during mprotect().
 
 Neil Brown continues to labor away at improving our swap-over-NFS support.
 
 David Hildenbrand has some fixes to anon page COWing versus
 get_user_pages().
 
 Peng Liu fixed some errors in the core hugetlb code.
 
 Joao Martins has reduced the amount of memory consumed by device-dax's
 compound devmaps.
 
 Some cleanups of the arch-specific pagemap code from Anshuman Khandual.
 
 Muchun Song has found and fixed some errors in the TLB flushing of
 transparent hugepages.
 
 Roman Gushchin has done more work on the memcg selftests.
 
 And, of course, many smaller fixes and cleanups.  Notably, the customary
 million cleanup serieses from Miaohe Lin.
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Merge tag 'mm-stable-2022-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:
 "Almost all of MM here. A few things are still getting finished off,
  reviewed, etc.

   - Yang Shi has improved the behaviour of khugepaged collapsing of
     readonly file-backed transparent hugepages.

   - Johannes Weiner has arranged for zswap memory use to be tracked and
     managed on a per-cgroup basis.

   - Munchun Song adds a /proc knob ("hugetlb_optimize_vmemmap") for
     runtime enablement of the recent huge page vmemmap optimization
     feature.

   - Baolin Wang contributes a series to fix some issues around hugetlb
     pagetable invalidation.

   - Zhenwei Pi has fixed some interactions between hwpoisoned pages and
     virtualization.

   - Tong Tiangen has enabled the use of the presently x86-only
     page_table_check debugging feature on arm64 and riscv.

   - David Vernet has done some fixup work on the memcg selftests.

   - Peter Xu has taught userfaultfd to handle write protection faults
     against shmem- and hugetlbfs-backed files.

   - More DAMON development from SeongJae Park - adding online tuning of
     the feature and support for monitoring of fixed virtual address
     ranges. Also easier discovery of which monitoring operations are
     available.

   - Nadav Amit has done some optimization of TLB flushing during
     mprotect().

   - Neil Brown continues to labor away at improving our swap-over-NFS
     support.

   - David Hildenbrand has some fixes to anon page COWing versus
     get_user_pages().

   - Peng Liu fixed some errors in the core hugetlb code.

   - Joao Martins has reduced the amount of memory consumed by
     device-dax's compound devmaps.

   - Some cleanups of the arch-specific pagemap code from Anshuman
     Khandual.

   - Muchun Song has found and fixed some errors in the TLB flushing of
     transparent hugepages.

   - Roman Gushchin has done more work on the memcg selftests.

  ... and, of course, many smaller fixes and cleanups. Notably, the
  customary million cleanup serieses from Miaohe Lin"

* tag 'mm-stable-2022-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (381 commits)
  mm: kfence: use PAGE_ALIGNED helper
  selftests: vm: add the "settings" file with timeout variable
  selftests: vm: add "test_hmm.sh" to TEST_FILES
  selftests: vm: check numa_available() before operating "merge_across_nodes" in ksm_tests
  selftests: vm: add migration to the .gitignore
  selftests/vm/pkeys: fix typo in comment
  ksm: fix typo in comment
  selftests: vm: add process_mrelease tests
  Revert "mm/vmscan: never demote for memcg reclaim"
  mm/kfence: print disabling or re-enabling message
  include/trace/events/percpu.h: cleanup for "percpu: improve percpu_alloc_percpu event trace"
  include/trace/events/mmflags.h: cleanup for "tracing: incorrect gfp_t conversion"
  mm: fix a potential infinite loop in start_isolate_page_range()
  MAINTAINERS: add Muchun as co-maintainer for HugeTLB
  zram: fix Kconfig dependency warning
  mm/shmem: fix shmem folio swapoff hang
  cgroup: fix an error handling path in alloc_pagecache_max_30M()
  mm: damon: use HPAGE_PMD_SIZE
  tracing: incorrect isolate_mote_t cast in mm_vmscan_lru_isolate
  nodemask.h: fix compilation error with GCC12
  ...
2022-05-26 12:32:41 -07:00
Linus Torvalds
cfeb2522c3 Perf events changes for this cycle were:
Platform PMU changes:
 =====================
 
  - x86/intel:
     - Add new Intel Alder Lake and Raptor Lake support
 
  - x86/amd:
     - AMD Zen4 IBS extensions support
     - Add AMD PerfMonV2 support
     - Add AMD Fam19h Branch Sampling support
 
 Generic changes:
 ================
 
  - signal: Deliver SIGTRAP on perf event asynchronously if blocked
 
    Perf instrumentation can be driven via SIGTRAP, but this causes a problem
    when SIGTRAP is blocked by a task & terminate the task.
 
    Allow user-space to request these signals asynchronously (after they get
    unblocked) & also give the information to the signal handler when this
    happens:
 
      " To give user space the ability to clearly distinguish synchronous from
        asynchronous signals, introduce siginfo_t::si_perf_flags and
        TRAP_PERF_FLAG_ASYNC (opted for flags in case more binary information is
        required in future).
 
        The resolution to the problem is then to (a) no longer force the signal
        (avoiding the terminations), but (b) tell user space via si_perf_flags
        if the signal was synchronous or not, so that such signals can be
        handled differently (e.g. let user space decide to ignore or consider
        the data imprecise). "
 
  - Unify/standardize the /sys/devices/cpu/events/* output format.
 
  - Misc fixes & cleanups.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'perf-core-2022-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf events updates from Ingo Molnar:
 "Platform PMU changes:

   - x86/intel:
      - Add new Intel Alder Lake and Raptor Lake support

   - x86/amd:
      - AMD Zen4 IBS extensions support
      - Add AMD PerfMonV2 support
      - Add AMD Fam19h Branch Sampling support

  Generic changes:

   - signal: Deliver SIGTRAP on perf event asynchronously if blocked

     Perf instrumentation can be driven via SIGTRAP, but this causes a
     problem when SIGTRAP is blocked by a task & terminate the task.

     Allow user-space to request these signals asynchronously (after
     they get unblocked) & also give the information to the signal
     handler when this happens:

       "To give user space the ability to clearly distinguish
        synchronous from asynchronous signals, introduce
        siginfo_t::si_perf_flags and TRAP_PERF_FLAG_ASYNC (opted for
        flags in case more binary information is required in future).

        The resolution to the problem is then to (a) no longer force the
        signal (avoiding the terminations), but (b) tell user space via
        si_perf_flags if the signal was synchronous or not, so that such
        signals can be handled differently (e.g. let user space decide
        to ignore or consider the data imprecise). "

   - Unify/standardize the /sys/devices/cpu/events/* output format.

   - Misc fixes & cleanups"

* tag 'perf-core-2022-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits)
  perf/x86/amd/core: Fix reloading events for SVM
  perf/x86/amd: Run AMD BRS code only on supported hw
  perf/x86/amd: Fix AMD BRS period adjustment
  perf/x86/amd: Remove unused variable 'hwc'
  perf/ibs: Fix comment
  perf/amd/ibs: Advertise zen4_ibs_extensions as pmu capability attribute
  perf/amd/ibs: Add support for L3 miss filtering
  perf/amd/ibs: Use ->is_visible callback for dynamic attributes
  perf/amd/ibs: Cascade pmu init functions' return value
  perf/x86/uncore: Add new Alder Lake and Raptor Lake support
  perf/x86/uncore: Clean up uncore_pci_ids[]
  perf/x86/cstate: Add new Alder Lake and Raptor Lake support
  perf/x86/msr: Add new Alder Lake and Raptor Lake support
  perf/x86: Add new Alder Lake and Raptor Lake support
  perf/amd/ibs: Use interrupt regs ip for stack unwinding
  perf/x86/amd/core: Add PerfMonV2 overflow handling
  perf/x86/amd/core: Add PerfMonV2 counter control
  perf/x86/amd/core: Detect available counters
  perf/x86/amd/core: Detect PerfMonV2 support
  x86/msr: Add PerfCntrGlobal* registers
  ...
2022-05-24 10:59:38 -07:00
Linus Torvalds
2319be1356 Locking changes in this cycle were:
- rwsem cleanups & optimizations/fixes:
     - Conditionally wake waiters in reader/writer slowpaths
     - Always try to wake waiters in out_nolock path
 
  - Add try_cmpxchg64() implementation, with arch optimizations - and use it to
    micro-optimize sched_clock_{local,remote}()
 
  - Various force-inlining fixes to address objdump instrumentation-check warnings
 
  - Add lock contention tracepoints:
 
     lock:contention_begin
     lock:contention_end
 
  - Misc smaller fixes & cleanups
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2022-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:

 - rwsem cleanups & optimizations/fixes:
    - Conditionally wake waiters in reader/writer slowpaths
    - Always try to wake waiters in out_nolock path

 - Add try_cmpxchg64() implementation, with arch optimizations - and use
   it to micro-optimize sched_clock_{local,remote}()

 - Various force-inlining fixes to address objdump instrumentation-check
   warnings

 - Add lock contention tracepoints:

    lock:contention_begin
    lock:contention_end

 - Misc smaller fixes & cleanups

* tag 'locking-core-2022-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/clock: Use try_cmpxchg64 in sched_clock_{local,remote}
  locking/atomic/x86: Introduce arch_try_cmpxchg64
  locking/atomic: Add generic try_cmpxchg64 support
  futex: Remove a PREEMPT_RT_FULL reference.
  locking/qrwlock: Change "queue rwlock" to "queued rwlock"
  lockdep: Delete local_irq_enable_in_hardirq()
  locking/mutex: Make contention tracepoints more consistent wrt adaptive spinning
  locking: Apply contention tracepoints in the slow path
  locking: Add lock contention tracepoints
  locking/rwsem: Always try to wake waiters in out_nolock path
  locking/rwsem: Conditionally wake waiters in reader/writer slowpaths
  locking/rwsem: No need to check for handoff bit if wait queue empty
  lockdep: Fix -Wunused-parameter for _THIS_IP_
  x86/mm: Force-inline __phys_addr_nodebug()
  x86/kvm/svm: Force-inline GHCB accessors
  task_stack, x86/cea: Force-inline stack helpers
2022-05-24 10:18:23 -07:00
Yang Shi
b265cdebdf sched: coredump.h: clarify the use of MMF_VM_HUGEPAGE
Patch series "Make khugepaged collapse readonly FS THP more consistent", v4.

The readonly FS THP relies on khugepaged to collapse THP for suitable
vmas.  But the behavior is inconsistent for "always" mode
(https://lore.kernel.org/linux-mm/00f195d4-d039-3cf2-d3a1-a2c88de397a0@suse.cz/).

The "always" mode means THP allocation should be tried all the time and
khugepaged should try to collapse THP all the time.  Of course the
allocation and collapse may fail due to other factors and conditions.

Currently file THP may not be collapsed by khugepaged even though all the
conditions are met.  That does break the semantics of "always" mode.

So make sure readonly FS vmas are registered to khugepaged to fix the
break.

Register suitable vmas in common mmap path, that could cover both readonly
FS vmas and shmem vmas, so remove the khugepaged calls in shmem.c.

The patch 1-7 are minor bug fixes, clean up and preparation patches. 
Patch 8 is the real meat.  

Tested with khugepaged test in selftests and the testcase provided by
Vlastimil Babka in
https://lore.kernel.org/lkml/df3b5d1c-a36b-2c73-3e27-99e74983de3a@suse.cz/
by commenting out MADV_HUGEPAGE call.


This patch (of 8):

MMF_VM_HUGEPAGE is set as long as the mm is available for khugepaged by
khugepaged_enter(), not only when VM_HUGEPAGE is set on vma.  Correct the
comment to avoid confusion.

Link: https://lkml.kernel.org/r/20220510203222.24246-1-shy828301@gmail.com
Link: https://lkml.kernel.org/r/20220510203222.24246-2-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Vlastmil Babka <vbabka@suse.cz>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-19 14:08:48 -07:00
Peter Zijlstra
31cae1eaae sched,signal,ptrace: Rework TASK_TRACED, TASK_STOPPED state
Currently ptrace_stop() / do_signal_stop() rely on the special states
TASK_TRACED and TASK_STOPPED resp. to keep unique state. That is, this
state exists only in task->__state and nowhere else.

There's two spots of bother with this:

 - PREEMPT_RT has task->saved_state which complicates matters,
   meaning task_is_{traced,stopped}() needs to check an additional
   variable.

 - An alternative freezer implementation that itself relies on a
   special TASK state would loose TASK_TRACED/TASK_STOPPED and will
   result in misbehaviour.

As such, add additional state to task->jobctl to track this state
outside of task->__state.

NOTE: this doesn't actually fix anything yet, just adds extra state.

--EWB
  * didn't add a unnecessary newline in signal.h
  * Update t->jobctl in signal_wake_up and ptrace_signal_wake_up
    instead of in signal_wake_up_state.  This prevents the clearing
    of TASK_STOPPED and TASK_TRACED from getting lost.
  * Added warnings if JOBCTL_STOPPED or JOBCTL_TRACED are not cleared

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220421150654.757693825@infradead.org
Tested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lkml.kernel.org/r/20220505182645.497868-12-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2022-05-11 14:37:06 -05:00
Eric W. Biederman
2500ad1c7f ptrace: Don't change __state
Stop playing with tsk->__state to remove TASK_WAKEKILL while a ptrace
command is executing.

Instead remove TASK_WAKEKILL from the definition of TASK_TRACED, and
implement a new jobctl flag TASK_PTRACE_FROZEN.  This new flag is set
in jobctl_freeze_task and cleared when ptrace_stop is awoken or in
jobctl_unfreeze_task (when ptrace_stop remains asleep).

In signal_wake_up add __TASK_TRACED to state along with TASK_WAKEKILL
when the wake up is for a fatal signal.  Skip adding __TASK_TRACED
when TASK_PTRACE_FROZEN is not set.  This has the same effect as
changing TASK_TRACED to __TASK_TRACED as all of the wake_ups that use
TASK_KILLABLE go through signal_wake_up.

Handle a ptrace_stop being called with a pending fatal signal.
Previously it would have been handled by schedule simply failing to
sleep.  As TASK_WAKEKILL is no longer part of TASK_TRACED schedule
will sleep with a fatal_signal_pending.   The code in signal_wake_up
guarantees that the code will be awaked by any fatal signal that
codes after TASK_TRACED is set.

Previously the __state value of __TASK_TRACED was changed to
TASK_RUNNING when woken up or back to TASK_TRACED when the code was
left in ptrace_stop.  Now when woken up ptrace_stop now clears
JOBCTL_PTRACE_FROZEN and when left sleeping ptrace_unfreezed_traced
clears JOBCTL_PTRACE_FROZEN.

Tested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lkml.kernel.org/r/20220505182645.497868-10-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2022-05-11 14:35:32 -05:00
Peter Zijlstra
47319846a9 Linux 5.18-rc5
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Merge branch 'v5.18-rc5'

Obtain the new INTEL_FAM6 stuff required.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
2022-05-11 16:27:06 +02:00
Eric W. Biederman
5bd2e97c86 fork: Generalize PF_IO_WORKER handling
Add fn and fn_arg members into struct kernel_clone_args and test for
them in copy_thread (instead of testing for PF_KTHREAD | PF_IO_WORKER).
This allows any task that wants to be a user space task that only runs
in kernel mode to use this functionality.

The code on x86 is an exception and still retains a PF_KTHREAD test
because x86 unlikely everything else handles kthreads slightly
differently than user space tasks that start with a function.

The functions that created tasks that start with a function
have been updated to set ".fn" and ".fn_arg" instead of
".stack" and ".stack_size".  These functions are fork_idle(),
create_io_thread(), kernel_thread(), and user_mode_thread().

Link: https://lkml.kernel.org/r/20220506141512.516114-4-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2022-05-07 09:01:59 -05:00
Eric W. Biederman
36cb0e1cda fork: Explicity test for idle tasks in copy_thread
The architectures ia64 and parisc have special handling for the idle
thread in copy_process.  Add a flag named idle to kernel_clone_args
and use it to explicity test if an idle process is being created.

Fullfill the expectations of the rest of the copy_thread
implemetations and pass a function pointer in .stack from fork_idle().
This makes what is happening in copy_thread better defined, and is
useful to make idle threads less special.

Link: https://lkml.kernel.org/r/20220506141512.516114-3-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2022-05-07 09:01:59 -05:00
Eric W. Biederman
c5febea095 fork: Pass struct kernel_clone_args into copy_thread
With io_uring we have started supporting tasks that are for most
purposes user space tasks that exclusively run code in kernel mode.

The kernel task that exec's init and tasks that exec user mode
helpers are also user mode tasks that just run kernel code
until they call kernel execve.

Pass kernel_clone_args into copy_thread so these oddball
tasks can be supported more cleanly and easily.

v2: Fix spelling of kenrel_clone_args on h8300
Link: https://lkml.kernel.org/r/20220506141512.516114-2-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2022-05-07 09:01:48 -05:00
Eric W. Biederman
343f4c49f2 kthread: Don't allocate kthread_struct for init and umh
If kthread_is_per_cpu runs concurrently with free_kthread_struct the
kthread_struct that was just freed may be read from.

This bug was introduced by commit 40966e316f ("kthread: Ensure
struct kthread is present for all kthreads").  When kthread_struct
started to be allocated for all tasks that have PF_KTHREAD set.  This
in turn required the kthread_struct to be freed in kernel_execve and
violated the assumption that kthread_struct will have the same
lifetime as the task.

Looking a bit deeper this only applies to callers of kernel_execve
which is just the init process and the user mode helper processes.
These processes really don't want to be kernel threads but are for
historical reasons.  Mostly that copy_thread does not know how to take
a kernel mode function to the process with for processes without
PF_KTHREAD or PF_IO_WORKER set.

Solve this by not allocating kthread_struct for the init process and
the user mode helper processes.

This is done by adding a kthread member to struct kernel_clone_args.
Setting kthread in fork_idle and kernel_thread.  Adding
user_mode_thread that works like kernel_thread except it does not set
kthread.  In fork only allocating the kthread_struct if .kthread is set.

I have looked at kernel/kthread.c and since commit 40966e316f
("kthread: Ensure struct kthread is present for all kthreads") there
have been no assumptions added that to_kthread or __to_kthread will
not return NULL.

There are a few callers of to_kthread or __to_kthread that assume a
non-NULL struct kthread pointer will be returned.  These functions are
kthread_data(), kthread_parmme(), kthread_exit(), kthread(),
kthread_park(), kthread_unpark(), kthread_stop().  All of those functions
can reasonably expected to be called when it is know that a task is a
kthread so that assumption seems reasonable.

Cc: stable@vger.kernel.org
Fixes: 40966e316f ("kthread: Ensure struct kthread is present for all kthreads")
Reported-by: Максим Кутявин <maximkabox13@gmail.com>
Link: https://lkml.kernel.org/r/20220506141512.516114-1-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2022-05-06 14:49:44 -05:00
Christophe Leroy
2cb4de085f mm: Add len and flags parameters to arch_get_mmap_end()
Powerpc needs flags and len to make decision on arch_get_mmap_end().

So add them as parameters to arch_get_mmap_end().

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/b556daabe7d2bdb2361c4d6130280da7c1ba2c14.1649523076.git.christophe.leroy@csgroup.eu
2022-05-05 22:11:57 +10:00
Christophe Leroy
4b439e25e2 mm, hugetlbfs: Allow an arch to always use generic versions of get_unmapped_area functions
Unlike most architectures, powerpc can only define at runtime
if it is going to use the generic arch_get_unmapped_area() or not.

Today, powerpc has a copy of the generic arch_get_unmapped_area()
because when selection HAVE_ARCH_UNMAPPED_AREA the generic
arch_get_unmapped_area() is not available.

Rename it generic_get_unmapped_area() and make it independent of
HAVE_ARCH_UNMAPPED_AREA.

Do the same for arch_get_unmapped_area_topdown() versus
HAVE_ARCH_UNMAPPED_AREA_TOPDOWN.

Do the same for hugetlb_get_unmapped_area() versus
HAVE_ARCH_HUGETLB_UNMAPPED_AREA.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/77f9d3e592f1c8511df9381aa1c4e754651da4d1.1649523076.git.christophe.leroy@csgroup.eu
2022-05-05 22:11:57 +10:00
Jens Axboe
e788be95a5 task_work: allow TWA_SIGNAL without a rescheduling IPI
Some use cases don't always need an IPI when sending a TWA_SIGNAL
notification. Add TWA_SIGNAL_NO_IPI, which is just like TWA_SIGNAL, except
it doesn't send an IPI to the target task. It merely sets
TIF_NOTIFY_SIGNAL and wakes up the task.

This can be useful in avoiding a forceful transition to the kernel if the
task is running in userspace. Depending on the task_work in question, it
may be quite fine waiting for the next reschedule or kernel enter anyway,
or the use case may even have other mechanisms for hinting to the task
that a transition may be useful. This can drive more cooperative
scheduling of task_work.

Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/821f42b6-7d91-8074-8212-d34998097de4@kernel.dk
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-04-30 08:39:32 -06:00
Marco Elver
78ed93d72d signal: Deliver SIGTRAP on perf event asynchronously if blocked
With SIGTRAP on perf events, we have encountered termination of
processes due to user space attempting to block delivery of SIGTRAP.
Consider this case:

    <set up SIGTRAP on a perf event>
    ...
    sigset_t s;
    sigemptyset(&s);
    sigaddset(&s, SIGTRAP | <and others>);
    sigprocmask(SIG_BLOCK, &s, ...);
    ...
    <perf event triggers>

When the perf event triggers, while SIGTRAP is blocked, force_sig_perf()
will force the signal, but revert back to the default handler, thus
terminating the task.

This makes sense for error conditions, but not so much for explicitly
requested monitoring. However, the expectation is still that signals
generated by perf events are synchronous, which will no longer be the
case if the signal is blocked and delivered later.

To give user space the ability to clearly distinguish synchronous from
asynchronous signals, introduce siginfo_t::si_perf_flags and
TRAP_PERF_FLAG_ASYNC (opted for flags in case more binary information is
required in future).

The resolution to the problem is then to (a) no longer force the signal
(avoiding the terminations), but (b) tell user space via si_perf_flags
if the signal was synchronous or not, so that such signals can be
handled differently (e.g. let user space decide to ignore or consider
the data imprecise).

The alternative of making the kernel ignore SIGTRAP on perf events if
the signal is blocked may work for some usecases, but likely causes
issues in others that then have to revert back to interception of
sigprocmask() (which we want to avoid). [ A concrete example: when using
breakpoint perf events to track data-flow, in a region of code where
signals are blocked, data-flow can no longer be tracked accurately.
When a relevant asynchronous signal is received after unblocking the
signal, the data-flow tracking logic needs to know its state is
imprecise. ]

Fixes: 97ba62b278 ("perf: Add support for SIGTRAP on perf events")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Link: https://lore.kernel.org/r/20220404111204.935357-1-elver@google.com
2022-04-22 12:14:05 +02:00
Christophe Leroy
5f24d5a579 mm, hugetlb: allow for "high" userspace addresses
This is a fix for commit f6795053da ("mm: mmap: Allow for "high"
userspace addresses") for hugetlb.

This patch adds support for "high" userspace addresses that are
optionally supported on the system and have to be requested via a hint
mechanism ("high" addr parameter to mmap).

Architectures such as powerpc and x86 achieve this by making changes to
their architectural versions of hugetlb_get_unmapped_area() function.
However, arm64 uses the generic version of that function.

So take into account arch_get_mmap_base() and arch_get_mmap_end() in
hugetlb_get_unmapped_area().  To allow that, move those two macros out
of mm/mmap.c into include/linux/sched/mm.h

If these macros are not defined in architectural code then they default
to (TASK_SIZE) and (base) so should not introduce any behavioural
changes to architectures that do not define them.

For the time being, only ARM64 is affected by this change.

Catalin (ARM64) said
 "We should have fixed hugetlb_get_unmapped_area() as well when we added
  support for 52-bit VA. The reason for commit f6795053da was to
  prevent normal mmap() from returning addresses above 48-bit by default
  as some user-space had hard assumptions about this.

  It's a slight ABI change if you do this for hugetlb_get_unmapped_area()
  but I doubt anyone would notice. It's more likely that the current
  behaviour would cause issues, so I'd rather have them consistent.

  Basically when arm64 gained support for 52-bit addresses we did not
  want user-space calling mmap() to suddenly get such high addresses,
  otherwise we could have inadvertently broken some programs (similar
  behaviour to x86 here). Hence we added commit f6795053da. But we
  missed hugetlbfs which could still get such high mmap() addresses. So
  in theory that's a potential regression that should have bee addressed
  at the same time as commit f6795053da (and before arm64 enabled
  52-bit addresses)"

Link: https://lkml.kernel.org/r/ab847b6edb197bffdfe189e70fb4ac76bfe79e0d.1650033747.git.christophe.leroy@csgroup.eu
Fixes: f6795053da ("mm: mmap: Allow for "high" userspace addresses")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: <stable@vger.kernel.org>	[5.0.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-04-21 20:01:09 -07:00
Zhen Ni
8a0441415b sched: Move energy_aware sysctls to topology.c
move energy_aware sysctls to topology.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <nizhen@uniontech.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2022-04-06 13:43:44 -07:00
Zhen Ni
d4ae80ffa6 sched: Move cfs_bandwidth_slice sysctls to fair.c
move cfs_bandwidth_slice sysctls to fair.c and use the
new register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <nizhen@uniontech.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2022-04-06 13:43:43 -07:00
Zhen Ni
3267e0156c sched: Move uclamp_util sysctls to core.c
move uclamp_util sysctls to core.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <nizhen@uniontech.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2022-04-06 13:43:43 -07:00
Zhen Ni
dafd7a9dad sched: Move rr_timeslice sysctls to rt.c
move rr_timeslice sysctls to rt.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <nizhen@uniontech.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2022-04-06 13:43:43 -07:00
Zhen Ni
84227c1288 sched: Move deadline_period sysctls to deadline.c
move deadline_period sysctls to deadline.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <nizhen@uniontech.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2022-04-06 13:43:43 -07:00
Zhen Ni
d9ab0e63fa sched: Move rt_period/runtime sysctls to rt.c
move rt_period/runtime sysctls to rt.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <nizhen@uniontech.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2022-04-06 13:43:43 -07:00
Zhen Ni
f5ef06d58b sched: Move schedstats sysctls to core.c
move schedstats sysctls to core.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <nizhen@uniontech.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2022-04-06 13:43:43 -07:00
Zhen Ni
a60707d74b sched: Move child_runs_first sysctls to fair.c
move child_runs_first sysctls to fair.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <nizhen@uniontech.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2022-04-06 13:43:43 -07:00
Borislav Petkov
e87f4152e5 task_stack, x86/cea: Force-inline stack helpers
Force-inline two stack helpers to fix the following objtool warnings:

  vmlinux.o: warning: objtool: in_task_stack()+0xc: call to task_stack_page() leaves .noinstr.text section
  vmlinux.o: warning: objtool: in_entry_stack()+0x10: call to cpu_entry_stack() leaves .noinstr.text section

Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220324183607.31717-2-bp@alien8.de
2022-04-04 10:13:07 +02:00
Linus Torvalds
1930a6e739 ptrace: Cleanups for v5.18
This set of changes removes tracehook.h, moves modification of all of
 the ptrace fields inside of siglock to remove races, adds a missing
 permission check to ptrace.c
 
 The removal of tracehook.h is quite significant as it has been a major
 source of confusion in recent years.  Much of that confusion was
 around task_work and TIF_NOTIFY_SIGNAL (which I have now decoupled
 making the semantics clearer).
 
 For people who don't know tracehook.h is a vestiage of an attempt to
 implement uprobes like functionality that was never fully merged, and
 was later superseeded by uprobes when uprobes was merged.  For many
 years now we have been removing what tracehook functionaly a little
 bit at a time.  To the point where now anything left in tracehook.h is
 some weird strange thing that is difficult to understand.
 
 Eric W. Biederman (15):
       ptrace: Move ptrace_report_syscall into ptrace.h
       ptrace/arm: Rename tracehook_report_syscall report_syscall
       ptrace: Create ptrace_report_syscall_{entry,exit} in ptrace.h
       ptrace: Remove arch_syscall_{enter,exit}_tracehook
       ptrace: Remove tracehook_signal_handler
       task_work: Remove unnecessary include from posix_timers.h
       task_work: Introduce task_work_pending
       task_work: Call tracehook_notify_signal from get_signal on all architectures
       task_work: Decouple TIF_NOTIFY_SIGNAL and task_work
       signal: Move set_notify_signal and clear_notify_signal into sched/signal.h
       resume_user_mode: Remove #ifdef TIF_NOTIFY_RESUME in set_notify_resume
       resume_user_mode: Move to resume_user_mode.h
       tracehook: Remove tracehook.h
       ptrace: Move setting/clearing ptrace_message into ptrace_stop
       ptrace: Return the signal to continue with from ptrace_stop
 
 Jann Horn (1):
       ptrace: Check PTRACE_O_SUSPEND_SECCOMP permission on PTRACE_SEIZE
 
 Yang Li (1):
       ptrace: Remove duplicated include in ptrace.c
 
  MAINTAINERS                          |   1 -
  arch/Kconfig                         |   5 +-
  arch/alpha/kernel/ptrace.c           |   5 +-
  arch/alpha/kernel/signal.c           |   4 +-
  arch/arc/kernel/ptrace.c             |   5 +-
  arch/arc/kernel/signal.c             |   4 +-
  arch/arm/kernel/ptrace.c             |  12 +-
  arch/arm/kernel/signal.c             |   4 +-
  arch/arm64/kernel/ptrace.c           |  14 +--
  arch/arm64/kernel/signal.c           |   4 +-
  arch/csky/kernel/ptrace.c            |   5 +-
  arch/csky/kernel/signal.c            |   4 +-
  arch/h8300/kernel/ptrace.c           |   5 +-
  arch/h8300/kernel/signal.c           |   4 +-
  arch/hexagon/kernel/process.c        |   4 +-
  arch/hexagon/kernel/signal.c         |   1 -
  arch/hexagon/kernel/traps.c          |   6 +-
  arch/ia64/kernel/process.c           |   4 +-
  arch/ia64/kernel/ptrace.c            |   6 +-
  arch/ia64/kernel/signal.c            |   1 -
  arch/m68k/kernel/ptrace.c            |   5 +-
  arch/m68k/kernel/signal.c            |   4 +-
  arch/microblaze/kernel/ptrace.c      |   5 +-
  arch/microblaze/kernel/signal.c      |   4 +-
  arch/mips/kernel/ptrace.c            |   5 +-
  arch/mips/kernel/signal.c            |   4 +-
  arch/nds32/include/asm/syscall.h     |   2 +-
  arch/nds32/kernel/ptrace.c           |   5 +-
  arch/nds32/kernel/signal.c           |   4 +-
  arch/nios2/kernel/ptrace.c           |   5 +-
  arch/nios2/kernel/signal.c           |   4 +-
  arch/openrisc/kernel/ptrace.c        |   5 +-
  arch/openrisc/kernel/signal.c        |   4 +-
  arch/parisc/kernel/ptrace.c          |   7 +-
  arch/parisc/kernel/signal.c          |   4 +-
  arch/powerpc/kernel/ptrace/ptrace.c  |   8 +-
  arch/powerpc/kernel/signal.c         |   4 +-
  arch/riscv/kernel/ptrace.c           |   5 +-
  arch/riscv/kernel/signal.c           |   4 +-
  arch/s390/include/asm/entry-common.h |   1 -
  arch/s390/kernel/ptrace.c            |   1 -
  arch/s390/kernel/signal.c            |   5 +-
  arch/sh/kernel/ptrace_32.c           |   5 +-
  arch/sh/kernel/signal_32.c           |   4 +-
  arch/sparc/kernel/ptrace_32.c        |   5 +-
  arch/sparc/kernel/ptrace_64.c        |   5 +-
  arch/sparc/kernel/signal32.c         |   1 -
  arch/sparc/kernel/signal_32.c        |   4 +-
  arch/sparc/kernel/signal_64.c        |   4 +-
  arch/um/kernel/process.c             |   4 +-
  arch/um/kernel/ptrace.c              |   5 +-
  arch/x86/kernel/ptrace.c             |   1 -
  arch/x86/kernel/signal.c             |   5 +-
  arch/x86/mm/tlb.c                    |   1 +
  arch/xtensa/kernel/ptrace.c          |   5 +-
  arch/xtensa/kernel/signal.c          |   4 +-
  block/blk-cgroup.c                   |   2 +-
  fs/coredump.c                        |   1 -
  fs/exec.c                            |   1 -
  fs/io-wq.c                           |   6 +-
  fs/io_uring.c                        |  11 +-
  fs/proc/array.c                      |   1 -
  fs/proc/base.c                       |   1 -
  include/asm-generic/syscall.h        |   2 +-
  include/linux/entry-common.h         |  47 +-------
  include/linux/entry-kvm.h            |   2 +-
  include/linux/posix-timers.h         |   1 -
  include/linux/ptrace.h               |  81 ++++++++++++-
  include/linux/resume_user_mode.h     |  64 ++++++++++
  include/linux/sched/signal.h         |  17 +++
  include/linux/task_work.h            |   5 +
  include/linux/tracehook.h            | 226 -----------------------------------
  include/uapi/linux/ptrace.h          |   2 +-
  kernel/entry/common.c                |  19 +--
  kernel/entry/kvm.c                   |   9 +-
  kernel/exit.c                        |   3 +-
  kernel/livepatch/transition.c        |   1 -
  kernel/ptrace.c                      |  47 +++++---
  kernel/seccomp.c                     |   1 -
  kernel/signal.c                      |  62 +++++-----
  kernel/task_work.c                   |   4 +-
  kernel/time/posix-cpu-timers.c       |   1 +
  mm/memcontrol.c                      |   2 +-
  security/apparmor/domain.c           |   1 -
  security/selinux/hooks.c             |   1 -
  85 files changed, 372 insertions(+), 495 deletions(-)
 
 Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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Merge tag 'ptrace-cleanups-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

Pull ptrace cleanups from Eric Biederman:
 "This set of changes removes tracehook.h, moves modification of all of
  the ptrace fields inside of siglock to remove races, adds a missing
  permission check to ptrace.c

  The removal of tracehook.h is quite significant as it has been a major
  source of confusion in recent years. Much of that confusion was around
  task_work and TIF_NOTIFY_SIGNAL (which I have now decoupled making the
  semantics clearer).

  For people who don't know tracehook.h is a vestiage of an attempt to
  implement uprobes like functionality that was never fully merged, and
  was later superseeded by uprobes when uprobes was merged. For many
  years now we have been removing what tracehook functionaly a little
  bit at a time. To the point where anything left in tracehook.h was
  some weird strange thing that was difficult to understand"

* tag 'ptrace-cleanups-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  ptrace: Remove duplicated include in ptrace.c
  ptrace: Check PTRACE_O_SUSPEND_SECCOMP permission on PTRACE_SEIZE
  ptrace: Return the signal to continue with from ptrace_stop
  ptrace: Move setting/clearing ptrace_message into ptrace_stop
  tracehook: Remove tracehook.h
  resume_user_mode: Move to resume_user_mode.h
  resume_user_mode: Remove #ifdef TIF_NOTIFY_RESUME in set_notify_resume
  signal: Move set_notify_signal and clear_notify_signal into sched/signal.h
  task_work: Decouple TIF_NOTIFY_SIGNAL and task_work
  task_work: Call tracehook_notify_signal from get_signal on all architectures
  task_work: Introduce task_work_pending
  task_work: Remove unnecessary include from posix_timers.h
  ptrace: Remove tracehook_signal_handler
  ptrace: Remove arch_syscall_{enter,exit}_tracehook
  ptrace: Create ptrace_report_syscall_{entry,exit} in ptrace.h
  ptrace/arm: Rename tracehook_report_syscall report_syscall
  ptrace: Move ptrace_report_syscall into ptrace.h
2022-03-28 17:29:53 -07:00
Linus Torvalds
7001052160 Add support for Intel CET-IBT, available since Tigerlake (11th gen), which is a
coarse grained, hardware based, forward edge Control-Flow-Integrity mechanism
 where any indirect CALL/JMP must target an ENDBR instruction or suffer #CP.
 
 Additionally, since Alderlake (12th gen)/Sapphire-Rapids, speculation is
 limited to 2 instructions (and typically fewer) on branch targets not starting
 with ENDBR. CET-IBT also limits speculation of the next sequential instruction
 after the indirect CALL/JMP [1].
 
 CET-IBT is fundamentally incompatible with retpolines, but provides, as
 described above, speculation limits itself.
 
 [1] https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/branch-history-injection.html
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Merge tag 'x86_core_for_5.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 CET-IBT (Control-Flow-Integrity) support from Peter Zijlstra:
 "Add support for Intel CET-IBT, available since Tigerlake (11th gen),
  which is a coarse grained, hardware based, forward edge
  Control-Flow-Integrity mechanism where any indirect CALL/JMP must
  target an ENDBR instruction or suffer #CP.

  Additionally, since Alderlake (12th gen)/Sapphire-Rapids, speculation
  is limited to 2 instructions (and typically fewer) on branch targets
  not starting with ENDBR. CET-IBT also limits speculation of the next
  sequential instruction after the indirect CALL/JMP [1].

  CET-IBT is fundamentally incompatible with retpolines, but provides,
  as described above, speculation limits itself"

[1] https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/branch-history-injection.html

* tag 'x86_core_for_5.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (53 commits)
  kvm/emulate: Fix SETcc emulation for ENDBR
  x86/Kconfig: Only allow CONFIG_X86_KERNEL_IBT with ld.lld >= 14.0.0
  x86/Kconfig: Only enable CONFIG_CC_HAS_IBT for clang >= 14.0.0
  kbuild: Fixup the IBT kbuild changes
  x86/Kconfig: Do not allow CONFIG_X86_X32_ABI=y with llvm-objcopy
  x86: Remove toolchain check for X32 ABI capability
  x86/alternative: Use .ibt_endbr_seal to seal indirect calls
  objtool: Find unused ENDBR instructions
  objtool: Validate IBT assumptions
  objtool: Add IBT/ENDBR decoding
  objtool: Read the NOENDBR annotation
  x86: Annotate idtentry_df()
  x86,objtool: Move the ASM_REACHABLE annotation to objtool.h
  x86: Annotate call_on_stack()
  objtool: Rework ASM_REACHABLE
  x86: Mark __invalid_creds() __noreturn
  exit: Mark do_group_exit() __noreturn
  x86: Mark stop_this_cpu() __noreturn
  objtool: Ignore extra-symbol code
  objtool: Rename --duplicate to --lto
  ...
2022-03-27 10:17:23 -07:00
Linus Torvalds
3bf03b9a08 Merge branch 'akpm' (patches from Andrew)
Merge updates from Andrew Morton:

 - A few misc subsystems: kthread, scripts, ntfs, ocfs2, block, and vfs

 - Most the MM patches which precede the patches in Willy's tree: kasan,
   pagecache, gup, swap, shmem, memcg, selftests, pagemap, mremap,
   sparsemem, vmalloc, pagealloc, memory-failure, mlock, hugetlb,
   userfaultfd, vmscan, compaction, mempolicy, oom-kill, migration, thp,
   cma, autonuma, psi, ksm, page-poison, madvise, memory-hotplug, rmap,
   zswap, uaccess, ioremap, highmem, cleanups, kfence, hmm, and damon.

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (227 commits)
  mm/damon/sysfs: remove repeat container_of() in damon_sysfs_kdamond_release()
  Docs/ABI/testing: add DAMON sysfs interface ABI document
  Docs/admin-guide/mm/damon/usage: document DAMON sysfs interface
  selftests/damon: add a test for DAMON sysfs interface
  mm/damon/sysfs: support DAMOS stats
  mm/damon/sysfs: support DAMOS watermarks
  mm/damon/sysfs: support schemes prioritization
  mm/damon/sysfs: support DAMOS quotas
  mm/damon/sysfs: support DAMON-based Operation Schemes
  mm/damon/sysfs: support the physical address space monitoring
  mm/damon/sysfs: link DAMON for virtual address spaces monitoring
  mm/damon: implement a minimal stub for sysfs-based DAMON interface
  mm/damon/core: add number of each enum type values
  mm/damon/core: allow non-exclusive DAMON start/stop
  Docs/damon: update outdated term 'regions update interval'
  Docs/vm/damon/design: update DAMON-Idle Page Tracking interference handling
  Docs/vm/damon: call low level monitoring primitives the operations
  mm/damon: remove unnecessary CONFIG_DAMON option
  mm/damon/paddr,vaddr: remove damon_{p,v}a_{target_valid,set_operations}()
  mm/damon/dbgfs-test: fix is_target_id() change
  ...
2022-03-22 16:11:53 -07:00
Huang Ying
c574bbe917 NUMA balancing: optimize page placement for memory tiering system
With the advent of various new memory types, some machines will have
multiple types of memory, e.g.  DRAM and PMEM (persistent memory).  The
memory subsystem of these machines can be called memory tiering system,
because the performance of the different types of memory are usually
different.

In such system, because of the memory accessing pattern changing etc,
some pages in the slow memory may become hot globally.  So in this
patch, the NUMA balancing mechanism is enhanced to optimize the page
placement among the different memory types according to hot/cold
dynamically.

In a typical memory tiering system, there are CPUs, fast memory and slow
memory in each physical NUMA node.  The CPUs and the fast memory will be
put in one logical node (called fast memory node), while the slow memory
will be put in another (faked) logical node (called slow memory node).
That is, the fast memory is regarded as local while the slow memory is
regarded as remote.  So it's possible for the recently accessed pages in
the slow memory node to be promoted to the fast memory node via the
existing NUMA balancing mechanism.

The original NUMA balancing mechanism will stop to migrate pages if the
free memory of the target node becomes below the high watermark.  This
is a reasonable policy if there's only one memory type.  But this makes
the original NUMA balancing mechanism almost do not work to optimize
page placement among different memory types.  Details are as follows.

It's the common cases that the working-set size of the workload is
larger than the size of the fast memory nodes.  Otherwise, it's
unnecessary to use the slow memory at all.  So, there are almost always
no enough free pages in the fast memory nodes, so that the globally hot
pages in the slow memory node cannot be promoted to the fast memory
node.  To solve the issue, we have 2 choices as follows,

a. Ignore the free pages watermark checking when promoting hot pages
   from the slow memory node to the fast memory node.  This will
   create some memory pressure in the fast memory node, thus trigger
   the memory reclaiming.  So that, the cold pages in the fast memory
   node will be demoted to the slow memory node.

b. Define a new watermark called wmark_promo which is higher than
   wmark_high, and have kswapd reclaiming pages until free pages reach
   such watermark.  The scenario is as follows: when we want to promote
   hot-pages from a slow memory to a fast memory, but fast memory's free
   pages would go lower than high watermark with such promotion, we wake
   up kswapd with wmark_promo watermark in order to demote cold pages and
   free us up some space.  So, next time we want to promote hot-pages we
   might have a chance of doing so.

The choice "a" may create high memory pressure in the fast memory node.
If the memory pressure of the workload is high, the memory pressure
may become so high that the memory allocation latency of the workload
is influenced, e.g.  the direct reclaiming may be triggered.

The choice "b" works much better at this aspect.  If the memory
pressure of the workload is high, the hot pages promotion will stop
earlier because its allocation watermark is higher than that of the
normal memory allocation.  So in this patch, choice "b" is implemented.
A new zone watermark (WMARK_PROMO) is added.  Which is larger than the
high watermark and can be controlled via watermark_scale_factor.

In addition to the original page placement optimization among sockets,
the NUMA balancing mechanism is extended to be used to optimize page
placement according to hot/cold among different memory types.  So the
sysctl user space interface (numa_balancing) is extended in a backward
compatible way as follow, so that the users can enable/disable these
functionality individually.

The sysctl is converted from a Boolean value to a bits field.  The
definition of the flags is,

- 0: NUMA_BALANCING_DISABLED
- 1: NUMA_BALANCING_NORMAL
- 2: NUMA_BALANCING_MEMORY_TIERING

We have tested the patch with the pmbench memory accessing benchmark
with the 80:20 read/write ratio and the Gauss access address
distribution on a 2 socket Intel server with Optane DC Persistent
Memory Model.  The test results shows that the pmbench score can
improve up to 95.9%.

Thanks Andrew Morton to help fix the document format error.

Link: https://lkml.kernel.org/r/20220221084529.1052339-3-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: zhongjiang-ali <zhongjiang-ali@linux.alibaba.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Feng Tang <feng.tang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-03-22 15:57:09 -07:00
Linus Torvalds
3fe2f7446f Changes in this cycle were:
- Cleanups for SCHED_DEADLINE
  - Tracing updates/fixes
  - CPU Accounting fixes
  - First wave of changes to optimize the overhead of the scheduler build,
    from the fast-headers tree - including placeholder *_api.h headers for
    later header split-ups.
  - Preempt-dynamic using static_branch() for ARM64
  - Isolation housekeeping mask rework; preperatory for further changes
  - NUMA-balancing: deal with CPU-less nodes
  - NUMA-balancing: tune systems that have multiple LLC cache domains per node (eg. AMD)
  - Updates to RSEQ UAPI in preparation for glibc usage
  - Lots of RSEQ/selftests, for same
  - Add Suren as PSI co-maintainer
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2022-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:

 - Cleanups for SCHED_DEADLINE

 - Tracing updates/fixes

 - CPU Accounting fixes

 - First wave of changes to optimize the overhead of the scheduler
   build, from the fast-headers tree - including placeholder *_api.h
   headers for later header split-ups.

 - Preempt-dynamic using static_branch() for ARM64

 - Isolation housekeeping mask rework; preperatory for further changes

 - NUMA-balancing: deal with CPU-less nodes

 - NUMA-balancing: tune systems that have multiple LLC cache domains per
   node (eg. AMD)

 - Updates to RSEQ UAPI in preparation for glibc usage

 - Lots of RSEQ/selftests, for same

 - Add Suren as PSI co-maintainer

* tag 'sched-core-2022-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (81 commits)
  sched/headers: ARM needs asm/paravirt_api_clock.h too
  sched/numa: Fix boot crash on arm64 systems
  headers/prep: Fix header to build standalone: <linux/psi.h>
  sched/headers: Only include <linux/entry-common.h> when CONFIG_GENERIC_ENTRY=y
  cgroup: Fix suspicious rcu_dereference_check() usage warning
  sched/preempt: Tell about PREEMPT_DYNAMIC on kernel headers
  sched/topology: Remove redundant variable and fix incorrect type in build_sched_domains
  sched/deadline,rt: Remove unused parameter from pick_next_[rt|dl]_entity()
  sched/deadline,rt: Remove unused functions for !CONFIG_SMP
  sched/deadline: Use __node_2_[pdl|dle]() and rb_first_cached() consistently
  sched/deadline: Merge dl_task_can_attach() and dl_cpu_busy()
  sched/deadline: Move bandwidth mgmt and reclaim functions into sched class source file
  sched/deadline: Remove unused def_dl_bandwidth
  sched/tracing: Report TASK_RTLOCK_WAIT tasks as TASK_UNINTERRUPTIBLE
  sched/tracing: Don't re-read p->state when emitting sched_switch event
  sched/rt: Plug rt_mutex_setprio() vs push_rt_task() race
  sched/cpuacct: Remove redundant RCU read lock
  sched/cpuacct: Optimize away RCU read lock
  sched/cpuacct: Fix charge percpu cpuusage
  sched/headers: Reorganize, clean up and optimize kernel/sched/sched.h dependencies
  ...
2022-03-22 14:39:12 -07:00
Linus Torvalds
bba90e0964 Core code updates:
- Reduce the amount of work to release a task stack in context
     switch. There is no real reason to do cgroup accounting and memory
     freeing in this performance sensitive context. Aside of this the
     invoked functions cannot be called from this preemption disabled
     context on PREEMPT_RT enabled kernels. Solve this by moving the
     accounting into do_exit() and delaying the freeing of the stack unless
     the vmap stack can be cached.
 
   - Provide a mechanism to delay raising signals from atomic context on
     PREEMPT_RT enabled kernels as sighand::lock cannot be acquired.  Store
     the information in the task struct and raise it in the exit path.
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Merge tag 'core-core-2022-03-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull core process handling RT latency updates from Thomas Gleixner:

 - Reduce the amount of work to release a task stack in context switch.
   There is no real reason to do cgroup accounting and memory freeing in
   this performance sensitive context.

   Aside of this the invoked functions cannot be called from this
   preemption disabled context on PREEMPT_RT enabled kernels. Solve this
   by moving the accounting into do_exit() and delaying the freeing of
   the stack unless the vmap stack can be cached.

 - Provide a mechanism to delay raising signals from atomic context on
   PREEMPT_RT enabled kernels as sighand::lock cannot be acquired. Store
   the information in the task struct and raise it in the exit path.

* tag 'core-core-2022-03-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  signal, x86: Delay calling signals in atomic on RT enabled kernels
  fork: Use IS_ENABLED() in account_kernel_stack()
  fork: Only cache the VMAP stack in finish_task_switch()
  fork: Move task stack accounting to do_exit()
  fork: Move memcg_charge_kernel_stack() into CONFIG_VMAP_STACK
  fork: Don't assign the stack pointer in dup_task_struct()
  fork, IA64: Provide alloc_thread_stack_node() for IA64
  fork: Duplicate task_struct before stack allocation
  fork: Redo ifdefs around task stack handling
2022-03-21 12:37:33 -07:00
Linus Torvalds
3fd33273a4 Reenable ENQCMD/PASID support:
- Simplify the PASID handling to allocate the PASID once, associate it to
    the mm of a process and free it on mm_exit(). The previous attempt of
    refcounted PASIDs and dynamic alloc()/free() turned out to be error
    prone and too complex. The PASID space is 20bits, so the case of
    resource exhaustion is a pure academic concern.
 
  - Populate the PASID MSR on demand via #GP to avoid racy updates via IPIs.
 
  - Reenable ENQCMD and let objtool check for the forbidden usage of ENQCMD
    in the kernel.
 
  - Update the documentation for Shared Virtual Addressing accordingly.
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Merge tag 'x86-pasid-2022-03-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 PASID support from Thomas Gleixner:
 "Reenable ENQCMD/PASID support:

   - Simplify the PASID handling to allocate the PASID once, associate
     it to the mm of a process and free it on mm_exit().

     The previous attempt of refcounted PASIDs and dynamic
     alloc()/free() turned out to be error prone and too complex. The
     PASID space is 20bits, so the case of resource exhaustion is a pure
     academic concern.

   - Populate the PASID MSR on demand via #GP to avoid racy updates via
     IPIs.

   - Reenable ENQCMD and let objtool check for the forbidden usage of
     ENQCMD in the kernel.

   - Update the documentation for Shared Virtual Addressing accordingly"

* tag 'x86-pasid-2022-03-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  Documentation/x86: Update documentation for SVA (Shared Virtual Addressing)
  tools/objtool: Check for use of the ENQCMD instruction in the kernel
  x86/cpufeatures: Re-enable ENQCMD
  x86/traps: Demand-populate PASID MSR via #GP
  sched: Define and initialize a flag to identify valid PASID in the task
  x86/fpu: Clear PASID when copying fpstate
  iommu/sva: Assign a PASID to mm on PASID allocation and free it on mm exit
  kernel/fork: Initialize mm's PASID
  iommu/ioasid: Introduce a helper to check for valid PASIDs
  mm: Change CONFIG option for mm->pasid field
  iommu/sva: Rename CONFIG_IOMMU_SVA_LIB to CONFIG_IOMMU_SVA
2022-03-21 12:28:13 -07:00
Ingo Molnar
8c490b42fe Merge branch 'x86/pasid' into x86/core, to resolve conflicts
Conflicts:
	tools/objtool/arch/x86/decode.c

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2022-03-15 12:50:59 +01:00
Peter Zijlstra
eae654f1c2 exit: Mark do_group_exit() __noreturn
vmlinux.o: warning: objtool: get_signal()+0x108: unreachable instruction

0000 000000000007f930 <get_signal>:
...
0103    7fa33:  e8 00 00 00 00          call   7fa38 <get_signal+0x108> 7fa34: R_X86_64_PLT32   do_group_exit-0x4
0108    7fa38:  41 8b 45 74             mov    0x74(%r13),%eax

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154319.351270711@infradead.org
2022-03-15 10:32:43 +01:00
Eric W. Biederman
593febb143 signal: Move set_notify_signal and clear_notify_signal into sched/signal.h
The header tracehook.h is no place for code to live.  The functions
set_notify_signal and clear_notify_signal are not about signals.  They
are about interruptions that act like signals.  The fundamental signal
primitives wind up calling set_notify_signal and clear_notify_signal.
Which means they need to be maintained with the signal code.

Since set_notify_signal and clear_notify_signal must be maintained
with the signal subsystem move them into sched/signal.h and claim them
as part of the signal subsystem.

Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20220309162454.123006-10-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2022-03-10 16:51:50 -06:00
Ingo Molnar
fbed5664b7 sched/headers: Make the <linux/sched/deadline.h> header build standalone
This header depends on various scheduler definitions.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>
2022-02-23 10:58:33 +01:00
Ingo Molnar
669f45f19c sched/headers: Add initial new headers as identity mappings
This allows code sharing between fast-headers tree and the vanilla
scheduler tree.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>
2022-02-23 10:58:28 +01:00
Sebastian Andrzej Siewior
1a03d3f13f fork: Move task stack accounting to do_exit()
There is no need to perform the stack accounting of the outgoing task in
its final schedule() invocation which happens with preemption disabled.
The task is leaving, the resources will be freed and the accounting can
happen in do_exit() before the actual schedule invocation which
frees the stack memory.

Move the accounting of the stack memory from release_task_stack() to
exit_task_stack_account() which then can be invoked from do_exit().

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20220217102406.3697941-7-bigeasy@linutronix.de
2022-02-22 22:25:02 +01:00
Ingo Molnar
6255b48aeb Linux 5.17-rc5
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Merge tag 'v5.17-rc5' into sched/core, to resolve conflicts

New conflicts in sched/core due to the following upstream fixes:

  44585f7bc0 ("psi: fix "defined but not used" warnings when CONFIG_PROC_FS=n")
  a06247c680 ("psi: Fix uaf issue when psi trigger is destroyed while being polled")

Conflicts:
	include/linux/psi_types.h
	kernel/sched/psi.c

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2022-02-21 11:53:51 +01:00
Peter Zijlstra
b1e8206582 sched: Fix yet more sched_fork() races
Where commit 4ef0c5c6b5 ("kernel/sched: Fix sched_fork() access an
invalid sched_task_group") fixed a fork race vs cgroup, it opened up a
race vs syscalls by not placing the task on the runqueue before it
gets exposed through the pidhash.

Commit 13765de814 ("sched/fair: Fix fault in reweight_entity") is
trying to fix a single instance of this, instead fix the whole class
of issues, effectively reverting this commit.

Fixes: 4ef0c5c6b5 ("kernel/sched: Fix sched_fork() access an invalid sched_task_group")
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Tadeusz Struk <tadeusz.struk@linaro.org>
Tested-by: Zhang Qiao <zhangqiao22@huawei.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lkml.kernel.org/r/YgoeCbwj5mbCR0qA@hirez.programming.kicks-ass.net
2022-02-19 11:11:05 +01:00
Frederic Weisbecker
04d4e665a6 sched/isolation: Use single feature type while referring to housekeeping cpumask
Refer to housekeeping APIs using single feature types instead of flags.
This prevents from passing multiple isolation features at once to
housekeeping interfaces, which soon won't be possible anymore as each
isolation features will have their own cpumask.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Phil Auld <pauld@redhat.com>
Link: https://lore.kernel.org/r/20220207155910.527133-5-frederic@kernel.org
2022-02-16 15:57:55 +01:00
Fenghua Yu
701fac4038 iommu/sva: Assign a PASID to mm on PASID allocation and free it on mm exit
PASIDs are process-wide. It was attempted to use refcounted PASIDs to
free them when the last thread drops the refcount. This turned out to
be complex and error prone. Given the fact that the PASID space is 20
bits, which allows up to 1M processes to have a PASID associated
concurrently, PASID resource exhaustion is not a realistic concern.

Therefore, it was decided to simplify the approach and stick with lazy
on demand PASID allocation, but drop the eager free approach and make an
allocated PASID's lifetime bound to the lifetime of the process.

Get rid of the refcounting mechanisms and replace/rename the interfaces
to reflect this new approach.

  [ bp: Massage commit message. ]

Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Joerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20220207230254.3342514-6-fenghua.yu@intel.com
2022-02-15 11:31:35 +01:00
Fenghua Yu
a6cbd44093 kernel/fork: Initialize mm's PASID
A new mm doesn't have a PASID yet when it's created. Initialize
the mm's PASID on fork() or for init_mm to INVALID_IOASID (-1).

INIT_PASID (0) is reserved for kernel legacy DMA PASID. It cannot be
allocated to a user process. Initializing the process's PASID to 0 may
cause confusion that's why the process uses the reserved kernel legacy
DMA PASID. Initializing the PASID to INVALID_IOASID (-1) explicitly
tells the process doesn't have a valid PASID yet.

Even though the only user of mm_pasid_init() is in fork.c, define it in
<linux/sched/mm.h> as the first of three mm/pasid life cycle functions
(init/set/drop) to keep these all together.

Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220207230254.3342514-5-fenghua.yu@intel.com
2022-02-14 19:51:47 +01:00
Mel Gorman
e496132ebe sched/fair: Adjust the allowed NUMA imbalance when SD_NUMA spans multiple LLCs
Commit 7d2b5dd0bc ("sched/numa: Allow a floating imbalance between NUMA
nodes") allowed an imbalance between NUMA nodes such that communicating
tasks would not be pulled apart by the load balancer. This works fine when
there is a 1:1 relationship between LLC and node but can be suboptimal
for multiple LLCs if independent tasks prematurely use CPUs sharing cache.

Zen* has multiple LLCs per node with local memory channels and due to
the allowed imbalance, it's far harder to tune some workloads to run
optimally than it is on hardware that has 1 LLC per node. This patch
allows an imbalance to exist up to the point where LLCs should be balanced
between nodes.

On a Zen3 machine running STREAM parallelised with OMP to have on instance
per LLC the results and without binding, the results are

                            5.17.0-rc0             5.17.0-rc0
                               vanilla       sched-numaimb-v6
MB/sec copy-16    162596.94 (   0.00%)   580559.74 ( 257.05%)
MB/sec scale-16   136901.28 (   0.00%)   374450.52 ( 173.52%)
MB/sec add-16     157300.70 (   0.00%)   564113.76 ( 258.62%)
MB/sec triad-16   151446.88 (   0.00%)   564304.24 ( 272.61%)

STREAM can use directives to force the spread if the OpenMP is new
enough but that doesn't help if an application uses threads and
it's not known in advance how many threads will be created.

Coremark is a CPU and cache intensive benchmark parallelised with
threads. When running with 1 thread per core, the vanilla kernel
allows threads to contend on cache. With the patch;

                               5.17.0-rc0             5.17.0-rc0
                                  vanilla       sched-numaimb-v5
Min       Score-16   368239.36 (   0.00%)   389816.06 (   5.86%)
Hmean     Score-16   388607.33 (   0.00%)   427877.08 *  10.11%*
Max       Score-16   408945.69 (   0.00%)   481022.17 (  17.62%)
Stddev    Score-16    15247.04 (   0.00%)    24966.82 ( -63.75%)
CoeffVar  Score-16        3.92 (   0.00%)        5.82 ( -48.48%)

It can also make a big difference for semi-realistic workloads
like specjbb which can execute arbitrary numbers of threads without
advance knowledge of how they should be placed. Even in cases where
the average performance is neutral, the results are more stable.

                               5.17.0-rc0             5.17.0-rc0
                                  vanilla       sched-numaimb-v6
Hmean     tput-1      71631.55 (   0.00%)    73065.57 (   2.00%)
Hmean     tput-8     582758.78 (   0.00%)   556777.23 (  -4.46%)
Hmean     tput-16   1020372.75 (   0.00%)  1009995.26 (  -1.02%)
Hmean     tput-24   1416430.67 (   0.00%)  1398700.11 (  -1.25%)
Hmean     tput-32   1687702.72 (   0.00%)  1671357.04 (  -0.97%)
Hmean     tput-40   1798094.90 (   0.00%)  2015616.46 *  12.10%*
Hmean     tput-48   1972731.77 (   0.00%)  2333233.72 (  18.27%)
Hmean     tput-56   2386872.38 (   0.00%)  2759483.38 (  15.61%)
Hmean     tput-64   2909475.33 (   0.00%)  2925074.69 (   0.54%)
Hmean     tput-72   2585071.36 (   0.00%)  2962443.97 (  14.60%)
Hmean     tput-80   2994387.24 (   0.00%)  3015980.59 (   0.72%)
Hmean     tput-88   3061408.57 (   0.00%)  3010296.16 (  -1.67%)
Hmean     tput-96   3052394.82 (   0.00%)  2784743.41 (  -8.77%)
Hmean     tput-104  2997814.76 (   0.00%)  2758184.50 (  -7.99%)
Hmean     tput-112  2955353.29 (   0.00%)  2859705.09 (  -3.24%)
Hmean     tput-120  2889770.71 (   0.00%)  2764478.46 (  -4.34%)
Hmean     tput-128  2871713.84 (   0.00%)  2750136.73 (  -4.23%)
Stddev    tput-1       5325.93 (   0.00%)     2002.53 (  62.40%)
Stddev    tput-8       6630.54 (   0.00%)    10905.00 ( -64.47%)
Stddev    tput-16     25608.58 (   0.00%)     6851.16 (  73.25%)
Stddev    tput-24     12117.69 (   0.00%)     4227.79 (  65.11%)
Stddev    tput-32     27577.16 (   0.00%)     8761.05 (  68.23%)
Stddev    tput-40     59505.86 (   0.00%)     2048.49 (  96.56%)
Stddev    tput-48    168330.30 (   0.00%)    93058.08 (  44.72%)
Stddev    tput-56    219540.39 (   0.00%)    30687.02 (  86.02%)
Stddev    tput-64    121750.35 (   0.00%)     9617.36 (  92.10%)
Stddev    tput-72    223387.05 (   0.00%)    34081.13 (  84.74%)
Stddev    tput-80    128198.46 (   0.00%)    22565.19 (  82.40%)
Stddev    tput-88    136665.36 (   0.00%)    27905.97 (  79.58%)
Stddev    tput-96    111925.81 (   0.00%)    99615.79 (  11.00%)
Stddev    tput-104   146455.96 (   0.00%)    28861.98 (  80.29%)
Stddev    tput-112    88740.49 (   0.00%)    58288.23 (  34.32%)
Stddev    tput-120   186384.86 (   0.00%)    45812.03 (  75.42%)
Stddev    tput-128    78761.09 (   0.00%)    57418.48 (  27.10%)

Similarly, for embarassingly parallel problems like NPB-ep, there are
improvements due to better spreading across LLC when the machine is not
fully utilised.

                              vanilla       sched-numaimb-v6
Min       ep.D       31.79 (   0.00%)       26.11 (  17.87%)
Amean     ep.D       31.86 (   0.00%)       26.17 *  17.86%*
Stddev    ep.D        0.07 (   0.00%)        0.05 (  24.41%)
CoeffVar  ep.D        0.22 (   0.00%)        0.20 (   7.97%)
Max       ep.D       31.93 (   0.00%)       26.21 (  17.91%)

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20220208094334.16379-3-mgorman@techsingularity.net
2022-02-11 23:30:08 +01:00
Zhen Ni
c8eaf6ac76 sched: move autogroup sysctls into its own file
move autogroup sysctls to autogroup.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <nizhen@uniontech.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220128095025.8745-1-nizhen@uniontech.com
2022-02-02 13:11:37 +01:00
Xiaoming Ni
bbe7a10ed8 hung_task: move hung_task sysctl interface to hung_task.c
The kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.

To help with this maintenance let's start by moving sysctls to places
where they actually belong.  The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic.

So move hung_task sysctl interface to hung_task.c and use
register_sysctl() to register the sysctl interface.

[mcgrof@kernel.org: commit log refresh and fixed 2-3 0day reported compile issues]

Link: https://lkml.kernel.org/r/20211123202347.818157-4-mcgrof@kernel.org
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qing Wang <wangqing@vivo.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Stephen Kitt <steve@sk2.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Antti Palosaari <crope@iki.fi>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Julia Lawall <julia.lawall@inria.fr>
Cc: Lukas Middendorf <kernel@tuxforce.de>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Phillip Potter <phil@philpotter.co.uk>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Cc: James E.J. Bottomley <jejb@linux.ibm.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-22 08:33:34 +02:00
Linus Torvalds
35ce8ae9ae Merge branch 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull signal/exit/ptrace updates from Eric Biederman:
 "This set of changes deletes some dead code, makes a lot of cleanups
  which hopefully make the code easier to follow, and fixes bugs found
  along the way.

  The end-game which I have not yet reached yet is for fatal signals
  that generate coredumps to be short-circuit deliverable from
  complete_signal, for force_siginfo_to_task not to require changing
  userspace configured signal delivery state, and for the ptrace stops
  to always happen in locations where we can guarantee on all
  architectures that the all of the registers are saved and available on
  the stack.

  Removal of profile_task_ext, profile_munmap, and profile_handoff_task
  are the big successes for dead code removal this round.

  A bunch of small bug fixes are included, as most of the issues
  reported were small enough that they would not affect bisection so I
  simply added the fixes and did not fold the fixes into the changes
  they were fixing.

  There was a bug that broke coredumps piped to systemd-coredump. I
  dropped the change that caused that bug and replaced it entirely with
  something much more restrained. Unfortunately that required some
  rebasing.

  Some successes after this set of changes: There are few enough calls
  to do_exit to audit in a reasonable amount of time. The lifetime of
  struct kthread now matches the lifetime of struct task, and the
  pointer to struct kthread is no longer stored in set_child_tid. The
  flag SIGNAL_GROUP_COREDUMP is removed. The field group_exit_task is
  removed. Issues where task->exit_code was examined with
  signal->group_exit_code should been examined were fixed.

  There are several loosely related changes included because I am
  cleaning up and if I don't include them they will probably get lost.

  The original postings of these changes can be found at:
     https://lkml.kernel.org/r/87a6ha4zsd.fsf@email.froward.int.ebiederm.org
     https://lkml.kernel.org/r/87bl1kunjj.fsf@email.froward.int.ebiederm.org
     https://lkml.kernel.org/r/87r19opkx1.fsf_-_@email.froward.int.ebiederm.org

  I trimmed back the last set of changes to only the obviously correct
  once. Simply because there was less time for review than I had hoped"

* 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (44 commits)
  ptrace/m68k: Stop open coding ptrace_report_syscall
  ptrace: Remove unused regs argument from ptrace_report_syscall
  ptrace: Remove second setting of PT_SEIZED in ptrace_attach
  taskstats: Cleanup the use of task->exit_code
  exit: Use the correct exit_code in /proc/<pid>/stat
  exit: Fix the exit_code for wait_task_zombie
  exit: Coredumps reach do_group_exit
  exit: Remove profile_handoff_task
  exit: Remove profile_task_exit & profile_munmap
  signal: clean up kernel-doc comments
  signal: Remove the helper signal_group_exit
  signal: Rename group_exit_task group_exec_task
  coredump: Stop setting signal->group_exit_task
  signal: Remove SIGNAL_GROUP_COREDUMP
  signal: During coredumps set SIGNAL_GROUP_EXIT in zap_process
  signal: Make coredump handling explicit in complete_signal
  signal: Have prepare_signal detect coredumps using signal->core_state
  signal: Have the oom killer detect coredumps using signal->core_state
  exit: Move force_uaccess back into do_exit
  exit: Guarantee make_task_dead leaks the tsk when calling do_task_exit
  ...
2022-01-17 05:49:30 +02:00
Linus Torvalds
f56caedaf9 Merge branch 'akpm' (patches from Andrew)
Merge misc updates from Andrew Morton:
 "146 patches.

  Subsystems affected by this patch series: kthread, ia64, scripts,
  ntfs, squashfs, ocfs2, vfs, and mm (slab-generic, slab, kmemleak,
  dax, kasan, debug, pagecache, gup, shmem, frontswap, memremap,
  memcg, selftests, pagemap, dma, vmalloc, memory-failure, hugetlb,
  userfaultfd, vmscan, mempolicy, oom-kill, hugetlbfs, migration, thp,
  ksm, page-poison, percpu, rmap, zswap, zram, cleanups, hmm, and
  damon)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (146 commits)
  mm/damon: hide kernel pointer from tracepoint event
  mm/damon/vaddr: hide kernel pointer from damon_va_three_regions() failure log
  mm/damon/vaddr: use pr_debug() for damon_va_three_regions() failure logging
  mm/damon/dbgfs: remove an unnecessary variable
  mm/damon: move the implementation of damon_insert_region to damon.h
  mm/damon: add access checking for hugetlb pages
  Docs/admin-guide/mm/damon/usage: update for schemes statistics
  mm/damon/dbgfs: support all DAMOS stats
  Docs/admin-guide/mm/damon/reclaim: document statistics parameters
  mm/damon/reclaim: provide reclamation statistics
  mm/damon/schemes: account how many times quota limit has exceeded
  mm/damon/schemes: account scheme actions that successfully applied
  mm/damon: remove a mistakenly added comment for a future feature
  Docs/admin-guide/mm/damon/usage: update for kdamond_pid and (mk|rm)_contexts
  Docs/admin-guide/mm/damon/usage: mention tracepoint at the beginning
  Docs/admin-guide/mm/damon/usage: remove redundant information
  Docs/admin-guide/mm/damon/usage: update for scheme quotas and watermarks
  mm/damon: convert macro functions to static inline functions
  mm/damon: modify damon_rand() macro to static inline function
  mm/damon: move damon_rand() definition into damon.h
  ...
2022-01-15 20:37:06 +02:00
NeilBrown
4034247a0d mm: introduce memalloc_retry_wait()
Various places in the kernel - largely in filesystems - respond to a
memory allocation failure by looping around and re-trying.  Some of
these cannot conveniently use __GFP_NOFAIL, for reasons such as:

 - a GFP_ATOMIC allocation, which __GFP_NOFAIL doesn't work on
 - a need to check for the process being signalled between failures
 - the possibility that other recovery actions could be performed
 - the allocation is quite deep in support code, and passing down an
   extra flag to say if __GFP_NOFAIL is wanted would be clumsy.

Many of these currently use congestion_wait() which (in almost all
cases) simply waits the given timeout - congestion isn't tracked for
most devices.

It isn't clear what the best delay is for loops, but it is clear that
the various filesystems shouldn't be responsible for choosing a timeout.

This patch introduces memalloc_retry_wait() with takes on that
responsibility.  Code that wants to retry a memory allocation can call
this function passing the GFP flags that were used.  It will wait
however is appropriate.

For now, it only considers __GFP_NORETRY and whatever
gfpflags_allow_blocking() tests.  If blocking is allowed without
__GFP_NORETRY, then alloc_page either made some reclaim progress, or
waited for a while, before failing.  So there is no need for much
further waiting.  memalloc_retry_wait() will wait until the current
jiffie ends.  If this condition is not met, then alloc_page() won't have
waited much if at all.  In that case memalloc_retry_wait() waits about
200ms.  This is the delay that most current loops uses.

linux/sched/mm.h needs to be included in some files now,
but linux/backing-dev.h does not.

Link: https://lkml.kernel.org/r/163754371968.13692.1277530886009912421@noble.neil.brown.name
Signed-off-by: NeilBrown <neilb@suse.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Chao Yu <chao@kernel.org>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-15 16:30:29 +02:00
Eric W. Biederman
49697335e0 signal: Remove the helper signal_group_exit
This helper is misleading.  It tests for an ongoing exec as well as
the process having received a fatal signal.

Sometimes it is appropriate to treat an on-going exec differently than
a process that is shutting down due to a fatal signal.  In particular
taking the fast path out of exit_signals instead of retargeting
signals is not appropriate during exec, and not changing the the exit
code in do_group_exit during exec.

Removing the helper makes it more obvious what is going on as both
cases must be coded for explicitly.

While removing the helper fix the two cases where I have observed
using signal_group_exit resulted in the wrong result.

In exit_signals only test for SIGNAL_GROUP_EXIT so that signals are
retargetted during an exec.

In do_group_exit use 0 as the exit code during an exec as de_thread
does not set group_exit_code.  As best as I can determine
group_exit_code has been is set to 0 most of the time during
de_thread.  During a thread group stop group_exit_code is set to the
stop signal and when the thread group receives SIGCONT group_exit_code
is reset to 0.

Link: https://lkml.kernel.org/r/20211213225350.27481-8-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2022-01-08 12:43:57 -06:00
Eric W. Biederman
60700e38fb signal: Rename group_exit_task group_exec_task
The only remaining user of group_exit_task is exec.  Rename the field
so that it is clear which part of the code uses it.

Update the comment above the definition of group_exec_task to document
how it is currently used.

Link: https://lkml.kernel.org/r/20211213225350.27481-7-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2022-01-08 12:43:57 -06:00
Eric W. Biederman
2f824d4d19 signal: Remove SIGNAL_GROUP_COREDUMP
After the previous cleanups "signal->core_state" is set whenever
SIGNAL_GROUP_COREDUMP is set and "signal->core_state" is tested
whenver the code wants to know if a coredump is in progress.  The
remaining tests of SIGNAL_GROUP_COREDUMP also test to see if
SIGNAL_GROUP_EXIT is set.  Similarly the only place that sets
SIGNAL_GROUP_COREDUMP also sets SIGNAL_GROUP_EXIT.

Which makes SIGNAL_GROUP_COREDUMP unecessary and redundant. So stop
setting SIGNAL_GROUP_COREDUMP, stop testing SIGNAL_GROUP_COREDUMP, and
remove it's definition.

With the setting of SIGNAL_GROUP_COREDUMP gone, coredump_finish no
longer needs to clear SIGNAL_GROUP_COREDUMP out of signal->flags
by setting SIGNAL_GROUP_EXIT.

Link: https://lkml.kernel.org/r/20211213225350.27481-5-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2022-01-08 12:43:57 -06:00
Rafael J. Wysocki
5ee22fa4a9 Merge branch 'cpufreq/arm/linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/vireshk/pm
Pull ARM cpufreq updates for 5.17-rc1 from Viresh Kumar:

"- Qcom cpufreq driver updates improve irq support (Ard Biesheuvel, Stephen Boyd,
   and Vladimir Zapolskiy).

 - Fixes double devm_remap for mediatek driver (Hector Yuan).

 - Introduces thermal pressure helpers (Lukasz Luba)."

* 'cpufreq/arm/linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/vireshk/pm:
  cpufreq: mediatek-hw: Fix double devm_remap in hotplug case
  cpufreq: qcom-hw: Use optional irq API
  cpufreq: qcom-hw: Set CPU affinity of dcvsh interrupts
  cpufreq: qcom-hw: Fix probable nested interrupt handling
  cpufreq: qcom-cpufreq-hw: Avoid stack buffer for IRQ name
  arch_topology: Remove unused topology_set_thermal_pressure() and related
  cpufreq: qcom-cpufreq-hw: Use new thermal pressure update function
  cpufreq: qcom-cpufreq-hw: Update offline CPUs per-cpu thermal pressure
  thermal: cpufreq_cooling: Use new thermal pressure update function
  arch_topology: Introduce thermal pressure update function
2021-12-30 15:49:54 +01:00
Eric W. Biederman
0e25498f8c exit: Add and use make_task_dead.
There are two big uses of do_exit.  The first is it's design use to be
the guts of the exit(2) system call.  The second use is to terminate
a task after something catastrophic has happened like a NULL pointer
in kernel code.

Add a function make_task_dead that is initialy exactly the same as
do_exit to cover the cases where do_exit is called to handle
catastrophic failure.  In time this can probably be reduced to just a
light wrapper around do_task_dead. For now keep it exactly the same so
that there will be no behavioral differences introducing this new
concept.

Replace all of the uses of do_exit that use it for catastraphic
task cleanup with make_task_dead to make it clear what the code
is doing.

As part of this rename rewind_stack_do_exit
rewind_stack_and_make_dead.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-13 12:04:45 -06:00
Eric W. Biederman
9d3f401c52 Merge SA_IMMUTABLE-fixes-for-v5.16-rc2
I completed the first batch of signal changes for v5.17 against
v5.16-rc1 before the SA_IMMUTABLE fixes where completed.  Which leaves
me with two lines of development that I want on my signal development
branch both rooted at v5.16-rc1.  Especially as I am hoping
to reach the point of being able to remove SA_IMMUTABLE.

Linus merged my SA_IMUTABLE fixes as:
7af959b5d5 ("Merge branch 'SA_IMMUTABLE-fixes-for-v5.16-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace")

To avoid rebasing the development changes that are currently complete I am
merging the work I sent upstream to Linus to make my life simpler.

The SA_IMMUTABLE changes as they are described in Linus's merge commit.

Pull exit-vs-signal handling fixes from Eric Biederman:
 "This is a small set of changes where debuggers were no longer able to
  intercept synchronous SIGTRAP and SIGSEGV, introduced by the exit
  cleanups.

  This is essentially the change you suggested with all of i's dotted
  and the t's crossed so that ptrace can intercept all of the cases it
  has been able to intercept the past, and all of the cases that made it
  to exit without giving ptrace a chance still don't give ptrace a
  chance"

* 'SA_IMMUTABLE-fixes-for-v5.16-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  signal: Replace force_fatal_sig with force_exit_sig when in doubt
  signal: Don't always set SA_IMMUTABLE for forced signals

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-03 15:36:59 -06:00
Frederic Weisbecker
e7f2be115f sched/cputime: Fix getrusage(RUSAGE_THREAD) with nohz_full
getrusage(RUSAGE_THREAD) with nohz_full may return shorter utime/stime
than the actual time.

task_cputime_adjusted() snapshots utime and stime and then adjust their
sum to match the scheduler maintained cputime.sum_exec_runtime.
Unfortunately in nohz_full, sum_exec_runtime is only updated once per
second in the worst case, causing a discrepancy against utime and stime
that can be updated anytime by the reader using vtime.

To fix this situation, perform an update of cputime.sum_exec_runtime
when the cputime snapshot reports the task as actually running while
the tick is disabled. The related overhead is then contained within the
relevant situations.

Reported-by: Hasegawa Hitomi <hasegawa-hitomi@fujitsu.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Hasegawa Hitomi <hasegawa-hitomi@fujitsu.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Acked-by: Phil Auld <pauld@redhat.com>
Link: https://lore.kernel.org/r/20211026141055.57358-3-frederic@kernel.org
2021-12-02 15:08:22 +01:00
Lukasz Luba
7e97b3dc25 arch_topology: Remove unused topology_set_thermal_pressure() and related
There is no need of this function (and related) since code has been
converted to use the new arch_update_thermal_pressure() API. The old
code can be removed.

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
2021-11-23 15:10:26 +05:30
Lukasz Luba
c214f12416 arch_topology: Introduce thermal pressure update function
The thermal pressure is a mechanism which is used for providing
information about reduced CPU performance to the scheduler. Usually code
has to convert the value from frequency units into capacity units,
which are understandable by the scheduler. Create a common conversion code
which can be just used via a handy API.

Internally, the topology_update_thermal_pressure() operates on frequency
in MHz and max CPU frequency is taken from 'freq_factor' (per-cpu).

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Thara Gopinath <thara.gopinath@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
2021-11-23 15:10:26 +05:30
Alexander Mikhalitsyn
85b6d24646 shm: extend forced shm destroy to support objects from several IPC nses
Currently, the exit_shm() function not designed to work properly when
task->sysvshm.shm_clist holds shm objects from different IPC namespaces.

This is a real pain when sysctl kernel.shm_rmid_forced = 1, because it
leads to use-after-free (reproducer exists).

This is an attempt to fix the problem by extending exit_shm mechanism to
handle shm's destroy from several IPC ns'es.

To achieve that we do several things:

1. add a namespace (non-refcounted) pointer to the struct shmid_kernel

2. during new shm object creation (newseg()/shmget syscall) we
   initialize this pointer by current task IPC ns

3. exit_shm() fully reworked such that it traverses over all shp's in
   task->sysvshm.shm_clist and gets IPC namespace not from current task
   as it was before but from shp's object itself, then call
   shm_destroy(shp, ns).

Note: We need to be really careful here, because as it was said before
(1), our pointer to IPC ns non-refcnt'ed.  To be on the safe side we
using special helper get_ipc_ns_not_zero() which allows to get IPC ns
refcounter only if IPC ns not in the "state of destruction".

Q/A

Q: Why can we access shp->ns memory using non-refcounted pointer?
A: Because shp object lifetime is always shorther than IPC namespace
   lifetime, so, if we get shp object from the task->sysvshm.shm_clist
   while holding task_lock(task) nobody can steal our namespace.

Q: Does this patch change semantics of unshare/setns/clone syscalls?
A: No. It's just fixes non-covered case when process may leave IPC
   namespace without getting task->sysvshm.shm_clist list cleaned up.

Link: https://lkml.kernel.org/r/67bb03e5-f79c-1815-e2bf-949c67047418@colorfullife.com
Link: https://lkml.kernel.org/r/20211109151501.4921-1-manfred@colorfullife.com
Fixes: ab602f7991 ("shm: make exit_shm work proportional to task activity")
Co-developed-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Cc: Vasily Averin <vvs@virtuozzo.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-20 10:35:54 -08:00
Eric W. Biederman
fcb116bc43 signal: Replace force_fatal_sig with force_exit_sig when in doubt
Recently to prevent issues with SECCOMP_RET_KILL and similar signals
being changed before they are delivered SA_IMMUTABLE was added.

Unfortunately this broke debuggers[1][2] which reasonably expect
to be able to trap synchronous SIGTRAP and SIGSEGV even when
the target process is not configured to handle those signals.

Add force_exit_sig and use it instead of force_fatal_sig where
historically the code has directly called do_exit.  This has the
implementation benefits of going through the signal exit path
(including generating core dumps) without the danger of allowing
userspace to ignore or change these signals.

This avoids userspace regressions as older kernels exited with do_exit
which debuggers also can not intercept.

In the future is should be possible to improve the quality of
implementation of the kernel by changing some of these force_exit_sig
calls to force_fatal_sig.  That can be done where it matters on
a case-by-case basis with careful analysis.

Reported-by: Kyle Huey <me@kylehuey.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
[1] https://lkml.kernel.org/r/CAP045AoMY4xf8aC_4QU_-j7obuEPYgTcnQQP3Yxk=2X90jtpjw@mail.gmail.com
[2] https://lkml.kernel.org/r/20211117150258.GB5403@xsang-OptiPlex-9020
Fixes: 00b06da29c ("signal: Add SA_IMMUTABLE to ensure forced siganls do not get changed")
Fixes: a3616a3c02 ("signal/m68k: Use force_sigsegv(SIGSEGV) in fpsp040_die")
Fixes: 83a1f27ad7 ("signal/powerpc: On swapcontext failure force SIGSEGV")
Fixes: 9bc508cf07 ("signal/s390: Use force_sigsegv in default_trap_handler")
Fixes: 086ec444f8 ("signal/sparc32: In setup_rt_frame and setup_fram use force_fatal_sig")
Fixes: c317d306d5 ("signal/sparc32: Exit with a fatal signal when try_to_clear_window_buffer fails")
Fixes: 695dd0d634 ("signal/x86: In emulate_vsyscall force a signal instead of calling do_exit")
Fixes: 1fbd60df8a ("signal/vm86_32: Properly send SIGSEGV when the vm86 state cannot be saved.")
Fixes: 941edc5bf1 ("exit/syscall_user_dispatch: Send ordinary signals on failure")
Link: https://lkml.kernel.org/r/871r3dqfv8.fsf_-_@email.froward.int.ebiederm.org
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Tested-by: Kyle Huey <khuey@kylehuey.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-11-19 09:15:58 -06:00
Eric W. Biederman
5768d8906b signal: Requeue signals in the appropriate queue
In the event that a tracer changes which signal needs to be delivered
and that signal is currently blocked then the signal needs to be
requeued for later delivery.

With the advent of CLONE_THREAD the kernel has 2 signal queues per
task.  The per process queue and the per task queue.  Update the code
so that if the signal is removed from the per process queue it is
requeued on the per process queue.  This is necessary to make it
appear the signal was never dequeued.

The rr debugger reasonably believes that the state of the process from
the last ptrace_stop it observed until PTRACE_EVENT_EXIT can be recreated
by simply letting a process run.  If a SIGKILL interrupts a ptrace_stop
this is not true today.

So return signals to their original queue in ptrace_signal so that
signals that are not delivered appear like they were never dequeued.

Fixes: 794aa320b79d ("[PATCH] sigfix-2.5.40-D6")
History Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.gi
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/87zgq4d5r4.fsf_-_@email.froward.int.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-11-17 10:39:12 -06:00
Linus Torvalds
5147da902e Merge branch 'exit-cleanups-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull exit cleanups from Eric Biederman:
 "While looking at some issues related to the exit path in the kernel I
  found several instances where the code is not using the existing
  abstractions properly.

  This set of changes introduces force_fatal_sig a way of sending a
  signal and not allowing it to be caught, and corrects the misuse of
  the existing abstractions that I found.

  A lot of the misuse of the existing abstractions are silly things such
  as doing something after calling a no return function, rolling BUG by
  hand, doing more work than necessary to terminate a kernel thread, or
  calling do_exit(SIGKILL) instead of calling force_sig(SIGKILL).

  In the review a deficiency in force_fatal_sig and force_sig_seccomp
  where ptrace or sigaction could prevent the delivery of the signal was
  found. I have added a change that adds SA_IMMUTABLE to change that
  makes it impossible to interrupt the delivery of those signals, and
  allows backporting to fix force_sig_seccomp

  And Arnd found an issue where a function passed to kthread_run had the
  wrong prototype, and after my cleanup was failing to build."

* 'exit-cleanups-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (23 commits)
  soc: ti: fix wkup_m3_rproc_boot_thread return type
  signal: Add SA_IMMUTABLE to ensure forced siganls do not get changed
  signal: Replace force_sigsegv(SIGSEGV) with force_fatal_sig(SIGSEGV)
  exit/r8188eu: Replace the macro thread_exit with a simple return 0
  exit/rtl8712: Replace the macro thread_exit with a simple return 0
  exit/rtl8723bs: Replace the macro thread_exit with a simple return 0
  signal/x86: In emulate_vsyscall force a signal instead of calling do_exit
  signal/sparc32: In setup_rt_frame and setup_fram use force_fatal_sig
  signal/sparc32: Exit with a fatal signal when try_to_clear_window_buffer fails
  exit/syscall_user_dispatch: Send ordinary signals on failure
  signal: Implement force_fatal_sig
  exit/kthread: Have kernel threads return instead of calling do_exit
  signal/s390: Use force_sigsegv in default_trap_handler
  signal/vm86_32: Properly send SIGSEGV when the vm86 state cannot be saved.
  signal/vm86_32: Replace open coded BUG_ON with an actual BUG_ON
  signal/sparc: In setup_tsb_params convert open coded BUG into BUG
  signal/powerpc: On swapcontext failure force SIGSEGV
  signal/sh: Use force_sig(SIGKILL) instead of do_group_exit(SIGKILL)
  signal/mips: Update (_save|_restore)_fp_context to fail with -EFAULT
  signal/sparc32: Remove unreachable do_exit in do_sparc_fault
  ...
2021-11-10 16:15:54 -08:00
Linus Torvalds
a602285ac1 Merge branch 'per_signal_struct_coredumps-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull per signal_struct coredumps from Eric Biederman:
 "Current coredumps are mixed up with the exit code, the signal handling
  code, and the ptrace code making coredumps much more complicated than
  necessary and difficult to follow.

  This series of changes starts with ptrace_stop and cleans it up,
  making it easier to follow what is happening in ptrace_stop. Then
  cleans up the exec interactions with coredumps. Then cleans up the
  coredump interactions with exit. Finally the coredump interactions
  with the signal handling code is cleaned up.

  The first and last changes are bug fixes for minor bugs.

  I believe the fact that vfork followed by execve can kill the process
  the called vfork if exec fails is sufficient justification to change
  the userspace visible behavior.

  In previous discussions some of these changes were organized
  differently and individually appeared to make the code base worse. As
  currently written I believe they all stand on their own as cleanups
  and bug fixes.

  Which means that even if the worst should happen and the last change
  needs to be reverted for some unimaginable reason, the code base will
  still be improved.

  If the worst does not happen there are a more cleanups that can be
  made. Signals that generate coredumps can easily become eligible for
  short circuit delivery in complete_signal. The entire rendezvous for
  generating a coredump can move into get_signal. The function
  force_sig_info_to_task be written in a way that does not modify the
  signal handling state of the target task (because coredumps are
  eligible for short circuit delivery). Many of these future cleanups
  can be done another way but nothing so cleanly as if coredumps become
  per signal_struct"

* 'per_signal_struct_coredumps-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  coredump: Limit coredumps to a single thread group
  coredump:  Don't perform any cleanups before dumping core
  exit: Factor coredump_exit_mm out of exit_mm
  exec: Check for a pending fatal signal instead of core_state
  ptrace: Remove the unnecessary arguments from arch_ptrace_stop
  signal: Remove the bogus sigkill_pending in ptrace_stop
2021-11-03 12:15:29 -07:00
Linus Torvalds
552ebfe022 parisc architecture updates for kernel v5.16-rc1
Lots of new features and fixes:
 * Added TOC (table of content) support, which is a debugging feature which is
   either initiated by pressing the TOC button or via command in the BMC. If
   pressed the Linux built-in KDB/KGDB will be called (Sven Schnelle)
 * Fix CONFIG_PREEMPT (Sven)
 * Fix unwinder on 64-bit kernels (Sven)
 * Various kgdb fixes (Sven)
 * Added KFENCE support (me)
 * Switch to ARCH_STACKWALK implementation (me)
 * Fix ptrace check on syscall return (me)
 * Fix kernel crash with fixmaps on PA1.x machines (me)
 * Move thread_info into task struct, aka CONFIG_THREAD_INFO_IN_TASK (me)
 * Updated defconfigs
 * Smaller cleanups, including Makefile cleanups (Masahiro Yamada),
   use kthread_run() macro (Cai Huoqing), use swap() macro (Yihao Han).
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Merge tag 'for-5.16/parisc-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux

Pull parisc updates from Helge Deller:
 "Lots of new features and fixes:

   - Added TOC (table of content) support, which is a debugging feature
     which is either initiated by pressing the TOC button or via command
     in the BMC. If pressed the Linux built-in KDB/KGDB will be called
     (Sven Schnelle)

   - Fix CONFIG_PREEMPT (Sven)

   - Fix unwinder on 64-bit kernels (Sven)

   - Various kgdb fixes (Sven)

   - Added KFENCE support (me)

   - Switch to ARCH_STACKWALK implementation (me)

   - Fix ptrace check on syscall return (me)

   - Fix kernel crash with fixmaps on PA1.x machines (me)

   - Move thread_info into task struct, aka CONFIG_THREAD_INFO_IN_TASK
     (me)

   - Updated defconfigs

   - Smaller cleanups, including Makefile cleanups (Masahiro Yamada),
     use kthread_run() macro (Cai Huoqing), use swap() macro (Yihao
     Han)"

* tag 'for-5.16/parisc-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux: (36 commits)
  parisc: Fix set_fixmap() on PA1.x CPUs
  parisc: Use swap() to swap values in setup_bootmem()
  parisc: Update defconfigs
  parisc: decompressor: clean up Makefile
  parisc: decompressor: remove repeated depenency of misc.o
  parisc: Remove unused constants from asm-offsets.c
  parisc/ftrace: use static key to enable/disable function graph tracer
  parisc/ftrace: set function trace function
  parisc: Make use of the helper macro kthread_run()
  parisc: mark xchg functions notrace
  parisc: enhance warning regarding usage of O_NONBLOCK
  parisc: Drop ifdef __KERNEL__ from non-uapi kernel headers
  parisc: Use PRIV_USER and PRIV_KERNEL in ptrace.h
  parisc: Use PRIV_USER in syscall.S
  parisc/kgdb: add kgdb_roundup() to make kgdb work with idle polling
  parisc: Move thread_info into task struct
  parisc: add support for TOC (transfer of control)
  parisc/firmware: add functions to retrieve TOC data
  parisc: add PIM TOC data structures
  parisc: move virt_map macro to assembly.h
  ...
2021-11-01 16:51:13 -07:00
Vincent Guittot
e60b56e46b sched/fair: Wait before decaying max_newidle_lb_cost
Decay max_newidle_lb_cost only when it has not been updated for a while
and ensure to not decay a recently changed value.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20211019123537.17146-4-vincent.guittot@linaro.org
2021-10-31 11:11:38 +01:00
Helge Deller
9cc2fa4f4a task_stack: Fix end_of_stack() for architectures with upwards-growing stack
The function end_of_stack() returns a pointer to the last entry of a
stack. For architectures like parisc where the stack grows upwards
return the pointer to the highest address in the stack.

Without this change I faced a crash on parisc, because the stackleak
functionality wrote STACKLEAK_POISON to the lowest address and thus
overwrote the first 4 bytes of the task_struct which included the
TIF_FLAGS.

Signed-off-by: Helge Deller <deller@gmx.de>
2021-10-30 23:11:01 +02:00
Eric W. Biederman
26d5badbcc signal: Implement force_fatal_sig
Add a simple helper force_fatal_sig that causes a signal to be
delivered to a process as if the signal handler was set to SIG_DFL.

Reimplement force_sigsegv based upon this new helper.  This fixes
force_sigsegv so that when it forces the default signal handler
to be used the code now forces the signal to be unblocked as well.

Reusing the tested logic in force_sig_info_to_task that was built for
force_sig_seccomp this makes the implementation trivial.

This is interesting both because it makes force_sigsegv simpler and
because there are a couple of buggy places in the kernel that call
do_exit(SIGILL) or do_exit(SIGSYS) because there is no straight
forward way today for those places to simply force the exit of a
process with the chosen signal.  Creating force_fatal_sig allows
those places to be implemented with normal signal exits.

Link: https://lkml.kernel.org/r/20211020174406.17889-13-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2021-10-29 14:31:33 -05:00
Barry Song
778c558f49 sched: Add cluster scheduler level in core and related Kconfig for ARM64
This patch adds scheduler level for clusters and automatically enables
the load balance among clusters. It will directly benefit a lot of
workload which loves more resources such as memory bandwidth, caches.

Testing has widely been done in two different hardware configurations of
Kunpeng920:

 24 cores in one NUMA(6 clusters in each NUMA node);
 32 cores in one NUMA(8 clusters in each NUMA node)

Workload is running on either one NUMA node or four NUMA nodes, thus,
this can estimate the effect of cluster spreading w/ and w/o NUMA load
balance.

* Stream benchmark:

4threads stream (on 1NUMA * 24cores = 24cores)
                stream                 stream
                w/o patch              w/ patch
MB/sec copy     29929.64 (   0.00%)    32932.68 (  10.03%)
MB/sec scale    29861.10 (   0.00%)    32710.58 (   9.54%)
MB/sec add      27034.42 (   0.00%)    32400.68 (  19.85%)
MB/sec triad    27225.26 (   0.00%)    31965.36 (  17.41%)

6threads stream (on 1NUMA * 24cores = 24cores)
                stream                 stream
                w/o patch              w/ patch
MB/sec copy     40330.24 (   0.00%)    42377.68 (   5.08%)
MB/sec scale    40196.42 (   0.00%)    42197.90 (   4.98%)
MB/sec add      37427.00 (   0.00%)    41960.78 (  12.11%)
MB/sec triad    37841.36 (   0.00%)    42513.64 (  12.35%)

12threads stream (on 1NUMA * 24cores = 24cores)
                stream                 stream
                w/o patch              w/ patch
MB/sec copy     52639.82 (   0.00%)    53818.04 (   2.24%)
MB/sec scale    52350.30 (   0.00%)    53253.38 (   1.73%)
MB/sec add      53607.68 (   0.00%)    55198.82 (   2.97%)
MB/sec triad    54776.66 (   0.00%)    56360.40 (   2.89%)

Thus, it could help memory-bound workload especially under medium load.
Similar improvement is also seen in lkp-pbzip2:

* lkp-pbzip2 benchmark

2-96 threads (on 4NUMA * 24cores = 96cores)
                  lkp-pbzip2              lkp-pbzip2
                  w/o patch               w/ patch
Hmean     tput-2   11062841.57 (   0.00%)  11341817.51 *   2.52%*
Hmean     tput-5   26815503.70 (   0.00%)  27412872.65 *   2.23%*
Hmean     tput-8   41873782.21 (   0.00%)  43326212.92 *   3.47%*
Hmean     tput-12  61875980.48 (   0.00%)  64578337.51 *   4.37%*
Hmean     tput-21 105814963.07 (   0.00%) 111381851.01 *   5.26%*
Hmean     tput-30 150349470.98 (   0.00%) 156507070.73 *   4.10%*
Hmean     tput-48 237195937.69 (   0.00%) 242353597.17 *   2.17%*
Hmean     tput-79 360252509.37 (   0.00%) 362635169.23 *   0.66%*
Hmean     tput-96 394571737.90 (   0.00%) 400952978.48 *   1.62%*

2-24 threads (on 1NUMA * 24cores = 24cores)
                 lkp-pbzip2               lkp-pbzip2
                 w/o patch                w/ patch
Hmean     tput-2   11071705.49 (   0.00%)  11296869.10 *   2.03%*
Hmean     tput-4   20782165.19 (   0.00%)  21949232.15 *   5.62%*
Hmean     tput-6   30489565.14 (   0.00%)  33023026.96 *   8.31%*
Hmean     tput-8   40376495.80 (   0.00%)  42779286.27 *   5.95%*
Hmean     tput-12  61264033.85 (   0.00%)  62995632.78 *   2.83%*
Hmean     tput-18  86697139.39 (   0.00%)  86461545.74 (  -0.27%)
Hmean     tput-24 104854637.04 (   0.00%) 104522649.46 *  -0.32%*

In the case of 6 threads and 8 threads, we see the greatest performance
improvement.

Similar improvement can be seen on lkp-pixz though the improvement is
smaller:

* lkp-pixz benchmark

2-24 threads lkp-pixz (on 1NUMA * 24cores = 24cores)
                  lkp-pixz               lkp-pixz
                  w/o patch              w/ patch
Hmean     tput-2   6486981.16 (   0.00%)  6561515.98 *   1.15%*
Hmean     tput-4  11645766.38 (   0.00%) 11614628.43 (  -0.27%)
Hmean     tput-6  15429943.96 (   0.00%) 15957350.76 *   3.42%*
Hmean     tput-8  19974087.63 (   0.00%) 20413746.98 *   2.20%*
Hmean     tput-12 28172068.18 (   0.00%) 28751997.06 *   2.06%*
Hmean     tput-18 39413409.54 (   0.00%) 39896830.55 *   1.23%*
Hmean     tput-24 49101815.85 (   0.00%) 49418141.47 *   0.64%*

* SPECrate benchmark

4,8,16 copies mcf_r(on 1NUMA * 32cores = 32cores)
		Base     	 	Base
		Run Time   	 	Rate
		-------  	 	---------
4 Copies	w/o 580 (w/ 570)       	w/o 11.1 (w/ 11.3)
8 Copies	w/o 647 (w/ 605)       	w/o 20.0 (w/ 21.4, +7%)
16 Copies	w/o 844 (w/ 844)       	w/o 30.6 (w/ 30.6)

32 Copies(on 4NUMA * 32 cores = 128cores)
[w/o patch]
                 Base     Base        Base
Benchmarks       Copies  Run Time     Rate
--------------- -------  ---------  ---------
500.perlbench_r      32        584       87.2  *
502.gcc_r            32        503       90.2  *
505.mcf_r            32        745       69.4  *
520.omnetpp_r        32       1031       40.7  *
523.xalancbmk_r      32        597       56.6  *
525.x264_r            1         --            CE
531.deepsjeng_r      32        336      109    *
541.leela_r          32        556       95.4  *
548.exchange2_r      32        513      163    *
557.xz_r             32        530       65.2  *
 Est. SPECrate2017_int_base              80.3

[w/ patch]
                  Base     Base        Base
Benchmarks       Copies  Run Time     Rate
--------------- -------  ---------  ---------
500.perlbench_r      32        580      87.8 (+0.688%)  *
502.gcc_r            32        477      95.1 (+5.432%)  *
505.mcf_r            32        644      80.3 (+13.574%) *
520.omnetpp_r        32        942      44.6 (+9.58%)   *
523.xalancbmk_r      32        560      60.4 (+6.714%%) *
525.x264_r            1         --           CE
531.deepsjeng_r      32        337      109  (+0.000%) *
541.leela_r          32        554      95.6 (+0.210%) *
548.exchange2_r      32        515      163  (+0.000%) *
557.xz_r             32        524      66.0 (+1.227%) *
 Est. SPECrate2017_int_base              83.7 (+4.062%)

On the other hand, it is slightly helpful to CPU-bound tasks like
kernbench:

* 24-96 threads kernbench (on 4NUMA * 24cores = 96cores)
                     kernbench              kernbench
                     w/o cluster            w/ cluster
Min       user-24    12054.67 (   0.00%)    12024.19 (   0.25%)
Min       syst-24     1751.51 (   0.00%)     1731.68 (   1.13%)
Min       elsp-24      600.46 (   0.00%)      598.64 (   0.30%)
Min       user-48    12361.93 (   0.00%)    12315.32 (   0.38%)
Min       syst-48     1917.66 (   0.00%)     1892.73 (   1.30%)
Min       elsp-48      333.96 (   0.00%)      332.57 (   0.42%)
Min       user-96    12922.40 (   0.00%)    12921.17 (   0.01%)
Min       syst-96     2143.94 (   0.00%)     2110.39 (   1.56%)
Min       elsp-96      211.22 (   0.00%)      210.47 (   0.36%)
Amean     user-24    12063.99 (   0.00%)    12030.78 *   0.28%*
Amean     syst-24     1755.20 (   0.00%)     1735.53 *   1.12%*
Amean     elsp-24      601.60 (   0.00%)      600.19 (   0.23%)
Amean     user-48    12362.62 (   0.00%)    12315.56 *   0.38%*
Amean     syst-48     1921.59 (   0.00%)     1894.95 *   1.39%*
Amean     elsp-48      334.10 (   0.00%)      332.82 *   0.38%*
Amean     user-96    12925.27 (   0.00%)    12922.63 (   0.02%)
Amean     syst-96     2146.66 (   0.00%)     2122.20 *   1.14%*
Amean     elsp-96      211.96 (   0.00%)      211.79 (   0.08%)

Note this patch isn't an universal win, it might hurt those workload
which can benefit from packing. Though tasks which want to take
advantages of lower communication latency of one cluster won't
necessarily been packed in one cluster while kernel is not aware of
clusters, they have some chance to be randomly packed. But this
patch will make them more likely spread.

Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Tested-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2021-10-15 11:25:16 +02:00
Zhang Qiao
4ef0c5c6b5 kernel/sched: Fix sched_fork() access an invalid sched_task_group
There is a small race between copy_process() and sched_fork()
where child->sched_task_group point to an already freed pointer.

	parent doing fork()      | someone moving the parent
				 | to another cgroup
  -------------------------------+-------------------------------
  copy_process()
      + dup_task_struct()<1>
				  parent move to another cgroup,
				  and free the old cgroup. <2>
      + sched_fork()
	+ __set_task_cpu()<3>
	+ task_fork_fair()
	  + sched_slice()<4>

In the worst case, this bug can lead to "use-after-free" and
cause panic as shown above:

  (1) parent copy its sched_task_group to child at <1>;

  (2) someone move the parent to another cgroup and free the old
      cgroup at <2>;

  (3) the sched_task_group and cfs_rq that belong to the old cgroup
      will be accessed at <3> and <4>, which cause a panic:

  [] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
  [] PGD 8000001fa0a86067 P4D 8000001fa0a86067 PUD 2029955067 PMD 0
  [] Oops: 0000 [#1] SMP PTI
  [] CPU: 7 PID: 648398 Comm: ebizzy Kdump: loaded Tainted: G           OE    --------- -  - 4.18.0.x86_64+ #1
  [] RIP: 0010:sched_slice+0x84/0xc0

  [] Call Trace:
  []  task_fork_fair+0x81/0x120
  []  sched_fork+0x132/0x240
  []  copy_process.part.5+0x675/0x20e0
  []  ? __handle_mm_fault+0x63f/0x690
  []  _do_fork+0xcd/0x3b0
  []  do_syscall_64+0x5d/0x1d0
  []  entry_SYSCALL_64_after_hwframe+0x65/0xca
  [] RIP: 0033:0x7f04418cd7e1

Between cgroup_can_fork() and cgroup_post_fork(), the cgroup
membership and thus sched_task_group can't change. So update child's
sched_task_group at sched_post_fork() and move task_fork() and
__set_task_cpu() (where accees the sched_task_group) from sched_fork()
to sched_post_fork().

Fixes: 8323f26ce3 ("sched: Fix race in task_group")
Signed-off-by: Zhang Qiao <zhangqiao22@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lkml.kernel.org/r/20210915064030.2231-1-zhangqiao22@huawei.com
2021-10-14 13:09:58 +02:00
Peter Zijlstra
5de62ea84a sched,livepatch: Use wake_up_if_idle()
Make sure to prod idle CPUs so they call klp_update_patch_state().

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Tested-by: Petr Mladek <pmladek@suse.com>
Tested-by: Vasily Gorbik <gor@linux.ibm.com> # on s390
Link: https://lkml.kernel.org/r/20210929151723.162004989@infradead.org
2021-10-14 13:09:25 +02:00
Eric W. Biederman
0258b5fd7c coredump: Limit coredumps to a single thread group
Today when a signal is delivered with a handler of SIG_DFL whose
default behavior is to generate a core dump not only that process but
every process that shares the mm is killed.

In the case of vfork this looks like a real world problem.  Consider
the following well defined sequence.

	if (vfork() == 0) {
		execve(...);
		_exit(EXIT_FAILURE);
	}

If a signal that generates a core dump is received after vfork but
before the execve changes the mm the process that called vfork will
also be killed (as the mm is shared).

Similarly if the execve fails after the point of no return the kernel
delivers SIGSEGV which will kill both the exec'ing process and because
the mm is shared the process that called vfork as well.

As far as I can tell this behavior is a violation of people's
reasonable expectations, POSIX, and is unnecessarily fragile when the
system is low on memory.

Solve this by making a userspace visible change to only kill a single
process/thread group.  This is possible because Jann Horn recently
modified[1] the coredump code so that the mm can safely be modified
while the coredump is happening.  With LinuxThreads long gone I don't
expect anyone to have a notice this behavior change in practice.

To accomplish this move the core_state pointer from mm_struct to
signal_struct, which allows different thread groups to coredump
simultatenously.

In zap_threads remove the work to kill anything except for the current
thread group.

v2: Remove core_state from the VM_BUG_ON_MM print to fix
    compile failure when CONFIG_DEBUG_VM is enabled.
    Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>

[1] a07279c9a8 ("binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot")
Fixes: d89f3847def4 ("[PATCH] thread-aware coredumps, 2.5.43-C3")
History-tree: git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Link: https://lkml.kernel.org/r/87y27mvnke.fsf@disp2133
Link: https://lkml.kernel.org/r/20211007144701.67592574@canb.auug.org.au
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-10-08 12:06:02 -05:00
Thomas Gleixner
8d491de6ed sched: Move mmdrop to RCU on RT
mmdrop() is invoked from finish_task_switch() by the incoming task to drop
the mm which was handed over by the previous task. mmdrop() can be quite
expensive which prevents an incoming real-time task from getting useful
work done.

Provide mmdrop_sched() which maps to mmdrop() on !RT kernels. On RT kernels
it delagates the eventually required invocation of __mmdrop() to RCU.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210928122411.648582026@linutronix.de
2021-10-05 15:52:09 +02:00
Linus Torvalds
2d338201d5 Merge branch 'akpm' (patches from Andrew)
Merge more updates from Andrew Morton:
 "147 patches, based on 7d2a07b769.

  Subsystems affected by this patch series: mm (memory-hotplug, rmap,
  ioremap, highmem, cleanups, secretmem, kfence, damon, and vmscan),
  alpha, percpu, procfs, misc, core-kernel, MAINTAINERS, lib,
  checkpatch, epoll, init, nilfs2, coredump, fork, pids, criu, kconfig,
  selftests, ipc, and scripts"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (94 commits)
  scripts: check_extable: fix typo in user error message
  mm/workingset: correct kernel-doc notations
  ipc: replace costly bailout check in sysvipc_find_ipc()
  selftests/memfd: remove unused variable
  Kconfig.debug: drop selecting non-existing HARDLOCKUP_DETECTOR_ARCH
  configs: remove the obsolete CONFIG_INPUT_POLLDEV
  prctl: allow to setup brk for et_dyn executables
  pid: cleanup the stale comment mentioning pidmap_init().
  kernel/fork.c: unexport get_{mm,task}_exe_file
  coredump: fix memleak in dump_vma_snapshot()
  fs/coredump.c: log if a core dump is aborted due to changed file permissions
  nilfs2: use refcount_dec_and_lock() to fix potential UAF
  nilfs2: fix memory leak in nilfs_sysfs_delete_snapshot_group
  nilfs2: fix memory leak in nilfs_sysfs_create_snapshot_group
  nilfs2: fix memory leak in nilfs_sysfs_delete_##name##_group
  nilfs2: fix memory leak in nilfs_sysfs_create_##name##_group
  nilfs2: fix NULL pointer in nilfs_##name##_attr_release
  nilfs2: fix memory leak in nilfs_sysfs_create_device_group
  trap: cleanup trap_init()
  init: move usermodehelper_enable() to populate_rootfs()
  ...
2021-09-08 12:55:35 -07:00
Nicholas Piggin
1e1c15839d fs/epoll: use a per-cpu counter for user's watches count
This counter tracks the number of watches a user has, to compare against
the 'max_user_watches' limit. This causes a scalability bottleneck on
SPECjbb2015 on large systems as there is only one user. Changing to a
per-cpu counter increases throughput of the benchmark by about 30% on a
16-socket, > 1000 thread system.

[rdunlap@infradead.org: fix build errors in kernel/user.c when CONFIG_EPOLL=n]
[npiggin@gmail.com: move ifdefs into wrapper functions, slightly improve panic message]
  Link: https://lkml.kernel.org/r/1628051945.fens3r99ox.astroid@bobo.none
[akpm@linux-foundation.org: tweak user_epoll_alloc(), per Guenter]
  Link: https://lkml.kernel.org/r/20210804191421.GA1900577@roeck-us.net

Link: https://lkml.kernel.org/r/20210802032013.2751916-1-npiggin@gmail.com
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reported-by: Anton Blanchard <anton@ozlabs.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-08 11:50:27 -07:00
Linus Torvalds
14726903c8 Merge branch 'akpm' (patches from Andrew)
Merge misc updates from Andrew Morton:
 "173 patches.

  Subsystems affected by this series: ia64, ocfs2, block, and mm (debug,
  pagecache, gup, swap, shmem, memcg, selftests, pagemap, mremap,
  bootmem, sparsemem, vmalloc, kasan, pagealloc, memory-failure,
  hugetlb, userfaultfd, vmscan, compaction, mempolicy, memblock,
  oom-kill, migration, ksm, percpu, vmstat, and madvise)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (173 commits)
  mm/madvise: add MADV_WILLNEED to process_madvise()
  mm/vmstat: remove unneeded return value
  mm/vmstat: simplify the array size calculation
  mm/vmstat: correct some wrong comments
  mm/percpu,c: remove obsolete comments of pcpu_chunk_populated()
  selftests: vm: add COW time test for KSM pages
  selftests: vm: add KSM merging time test
  mm: KSM: fix data type
  selftests: vm: add KSM merging across nodes test
  selftests: vm: add KSM zero page merging test
  selftests: vm: add KSM unmerge test
  selftests: vm: add KSM merge test
  mm/migrate: correct kernel-doc notation
  mm: wire up syscall process_mrelease
  mm: introduce process_mrelease system call
  memblock: make memblock_find_in_range method private
  mm/mempolicy.c: use in_task() in mempolicy_slab_node()
  mm/mempolicy: unify the create() func for bind/interleave/prefer-many policies
  mm/mempolicy: advertise new MPOL_PREFERRED_MANY
  mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY
  ...
2021-09-03 10:08:28 -07:00
Vasily Averin
55a68c8239 memcg: replace in_interrupt() by !in_task() in active_memcg()
set_active_memcg() uses in_interrupt() check to select proper storage for
cgroup: pointer on task struct or per-cpu pointer.

It isn't fully correct: obsoleted in_interrupt() includes tasks with
disabled BH.  It's better to use '!in_task()' instead.

Link: https://lkml.org/lkml/2021/7/26/487
Link: https://lkml.kernel.org/r/ed4448b0-4970-616f-7368-ef9dd3cb628d@virtuozzo.com
Fixes: 37d5985c00 ("mm: kmem: prepare remote memcg charging infra for interrupt contexts")
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 09:58:13 -07:00
Matthew Wilcox (Oracle)
4f3eaf452a mm: report a more useful address for reclaim acquisition
A recent lockdep report included these lines:

[   96.177910] 3 locks held by containerd/770:
[   96.177934]  #0: ffff88810815ea28 (&mm->mmap_lock#2){++++}-{3:3},
at: do_user_addr_fault+0x115/0x770
[   96.177999]  #1: ffffffff82915020 (rcu_read_lock){....}-{1:2}, at:
get_swap_device+0x33/0x140
[   96.178057]  #2: ffffffff82955ba0 (fs_reclaim){+.+.}-{0:0}, at:
__fs_reclaim_acquire+0x5/0x30

While it was not useful to that bug report to know where the reclaim lock
had been acquired, it might be useful under other circumstances.  Allow
the caller of __fs_reclaim_acquire to specify the instruction pointer to
use.

Link: https://lkml.kernel.org/r/20210719185709.1755149-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 09:58:10 -07:00
Linus Torvalds
bcfeebbff3 Merge branch 'exit-cleanups-for-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull exit cleanups from Eric Biederman:
 "In preparation of doing something about PTRACE_EVENT_EXIT I have
  started cleaning up various pieces of code related to do_exit. Most of
  that code I did not manage to get tested and reviewed before the merge
  window opened but a handful of very useful cleanups are ready to be
  merged.

  The first change is simply the removal of the bdflush system call. The
  code has now been disabled long enough that even the oldest userspace
  working userspace setups anyone can find to test are fine with the
  bdflush system call being removed.

  Changing m68k fsp040_die to use force_sigsegv(SIGSEGV) instead of
  calling do_exit directly is interesting only in that it is nearly the
  most difficult of the incorrect uses of do_exit to remove.

  The change to the seccomp code to simply send a signal instead of
  calling do_coredump directly is a very nice little cleanup made
  possible by realizing the existing signal sending helpers were missing
  a little bit of functionality that is easy to provide"

* 'exit-cleanups-for-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  signal/seccomp: Dump core when there is only one live thread
  signal/seccomp: Refactor seccomp signal and coredump generation
  signal/m68k: Use force_sigsegv(SIGSEGV) in fpsp040_die
  exit/bdflush: Remove the deprecated bdflush system call
2021-09-01 14:52:05 -07:00
Linus Torvalds
48983701a1 Merge branch 'siginfo-si_trapno-for-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull siginfo si_trapno updates from Eric Biederman:
 "The full set of si_trapno changes was not appropriate as a fix for the
  newly added SIGTRAP TRAP_PERF, and so I postponed the rest of the
  related cleanups.

  This is the rest of the cleanups for si_trapno that reduces it from
  being a really weird arch special case that is expect to be always
  present (but isn't) on the architectures that support it to being yet
  another field in the _sigfault union of struct siginfo.

  The changes have been reviewed and marinated in linux-next. With the
  removal of this awkward special case new code (like SIGTRAP TRAP_PERF)
  that works across architectures should be easier to write and
  maintain"

* 'siginfo-si_trapno-for-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency
  signal: Verify the alignment and size of siginfo_t
  signal: Remove the generic __ARCH_SI_TRAPNO support
  signal/alpha: si_trapno is only used with SIGFPE and SIGTRAP TRAP_UNK
  signal/sparc: si_trapno is only used with SIGILL ILL_ILLTRP
  arm64: Add compile-time asserts for siginfo_t offsets
  arm: Add compile-time asserts for siginfo_t offsets
  sparc64: Add compile-time asserts for siginfo_t offsets
2021-09-01 14:42:36 -07:00
Linus Torvalds
8596e589b7 Updates for timekeeping, timers and related drivers:
Core code:
 
   - Cure a couple of incorrectness issues in the posix CPU timer code to
     prevent that the tick dependency for NOHZ full is kept alive for no
     reason.
 
   - Avoid expensive double reprogramming of the clockevent device in
     hrtimer_start_range_ns().
 
   - Avoid pointless SMP function calls when the clock was set to avoid
     disturbing CPUs which do not have any affected timers queued.
 
   - Make the clocksource watchdog test work correctly when CONFIG_HZ is
     less than 100.
 
 Drivers:
 
   - Prefer the ARM architected timer over the Exynos timer which is way
     more expensive to access.
 
   - Add device tree bindings for new Ingenic SoCs
 
   - The usual improvements and cleanups all over the place
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Merge tag 'timers-core-2021-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer updates from Thomas Gleixner:
 "Updates for timekeeping, timers and related drivers:

  Core code:

   - Cure a couple of correctness issues in the posix CPU timer code to
     prevent that the tick dependency for NOHZ full is kept alive for no
     reason.

   - Avoid expensive double reprogramming of the clockevent device in
     hrtimer_start_range_ns().

   - Avoid pointless SMP function calls when the clock was set to avoid
     disturbing CPUs which do not have any affected timers queued.

   - Make the clocksource watchdog test work correctly when CONFIG_HZ is
     less than 100.

  Drivers:

   - Prefer the ARM architected timer over the Exynos timer which is way
     more expensive to access.

   - Add device tree bindings for new Ingenic SoCs

   - The usual improvements and cleanups all over the place"

* tag 'timers-core-2021-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (29 commits)
  clocksource: Make clocksource watchdog test safe for slow-HZ systems
  dt-bindings: timer: Add ABIs for new Ingenic SoCs
  clocksource/drivers/fttmr010: Pass around less pointers
  clocksource/drivers/mediatek: Optimize systimer irq clear flow on shutdown
  clocksource/drivers/ingenic: Use bitfield macro helpers
  clocksource/drivers/sh_cmt: Fix wrong setting if don't request IRQ for clock source channel
  dt-bindings: timer: convert rockchip,rk-timer.txt to YAML
  clocksource/drivers/exynos_mct: Mark MCT device as CLOCK_EVT_FEAT_PERCPU
  clocksource/drivers/exynos_mct: Prioritise Arm arch timer on arm64
  hrtimer: Unbreak hrtimer_force_reprogram()
  hrtimer: Use raw_cpu_ptr() in clock_was_set()
  hrtimer: Avoid more SMP function calls in clock_was_set()
  hrtimer: Avoid unnecessary SMP function calls in clock_was_set()
  hrtimer: Add bases argument to clock_was_set()
  time/timekeeping: Avoid invoking clock_was_set() twice
  timekeeping: Distangle resume and clock-was-set events
  timerfd: Provide timerfd_resume()
  hrtimer: Force clock_was_set() handling for the HIGHRES=n, NOHZ=y case
  hrtimer: Ensure timerfd notification for HIGHRES=n
  hrtimer: Consolidate reprogramming code
  ...
2021-08-30 15:31:33 -07:00
Linus Torvalds
e5e726f7bb Updates for locking and atomics:
The regular pile:
 
   - A few improvements to the mutex code
 
   - Documentation updates for atomics to clarify the difference between
     cmpxchg() and try_cmpxchg() and to explain the forward progress
     expectations.
 
   - Simplification of the atomics fallback generator
 
   - The addition of arch_atomic_long*() variants and generic arch_*()
     bitops based on them.
 
   - Add the missing might_sleep() invocations to the down*() operations of
     semaphores.
 
 The PREEMPT_RT locking core:
 
   - Scheduler updates to support the state preserving mechanism for
     'sleeping' spin- and rwlocks on RT. This mechanism is carefully
     preserving the state of the task when blocking on a 'sleeping' spin- or
     rwlock and takes regular wake-ups targeted at the same task into
     account. The preserved or updated (via a regular wakeup) state is
     restored when the lock has been acquired.
 
   - Restructuring of the rtmutex code so it can be utilized and extended
     for the RT specific lock variants.
 
   - Restructuring of the ww_mutex code to allow sharing of the ww_mutex
     specific functionality for rtmutex based ww_mutexes.
 
   - Header file disentangling to allow substitution of the regular lock
     implementations with the PREEMPT_RT variants without creating an
     unmaintainable #ifdef mess.
 
   - Shared base code for the PREEMPT_RT specific rw_semaphore and rwlock
     implementations. Contrary to the regular rw_semaphores and rwlocks the
     PREEMPT_RT implementation is writer unfair because it is infeasible to
     do priority inheritance on multiple readers. Experience over the years
     has shown that real-time workloads are not the typical workloads which
     are sensitive to writer starvation. The alternative solution would be
     to allow only a single reader which has been tried and discarded as it
     is a major bottleneck especially for mmap_sem. Aside of that many of
     the writer starvation critical usage sites have been converted to a
     writer side mutex/spinlock and RCU read side protections in the past
     decade so that the issue is less prominent than it used to be.
 
   - The actual rtmutex based lock substitutions for PREEMPT_RT enabled
     kernels which affect mutex, ww_mutex, rw_semaphore, spinlock_t and
     rwlock_t. The spin/rw_lock*() functions disable migration across the
     critical section to preserve the existing semantics vs. per CPU
     variables.
 
   - Rework of the futex REQUEUE_PI mechanism to handle the case of early
     wake-ups which interleave with a re-queue operation to prevent the
     situation that a task would be blocked on both the rtmutex associated
     to the outer futex and the rtmutex based hash bucket spinlock.
 
     While this situation cannot happen on !RT enabled kernels the changes
     make the underlying concurrency problems easier to understand in
     general. As a result the difference between !RT and RT kernels is
     reduced to the handling of waiting for the critical section. !RT
     kernels simply spin-wait as before and RT kernels utilize rcu_wait().
 
   - The substitution of local_lock for PREEMPT_RT with a spinlock which
     protects the critical section while staying preemptible. The CPU
     locality is established by disabling migration.
 
   The underlying concepts of this code have been in use in PREEMPT_RT for
   way more than a decade. The code has been refactored several times over
   the years and this final incarnation has been optimized once again to be
   as non-intrusive as possible, i.e. the RT specific parts are mostly
   isolated.
 
   It has been extensively tested in the 5.14-rt patch series and it has
   been verified that !RT kernels are not affected by these changes.
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Merge tag 'locking-core-2021-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking and atomics updates from Thomas Gleixner:
 "The regular pile:

   - A few improvements to the mutex code

   - Documentation updates for atomics to clarify the difference between
     cmpxchg() and try_cmpxchg() and to explain the forward progress
     expectations.

   - Simplification of the atomics fallback generator

   - The addition of arch_atomic_long*() variants and generic arch_*()
     bitops based on them.

   - Add the missing might_sleep() invocations to the down*() operations
     of semaphores.

  The PREEMPT_RT locking core:

   - Scheduler updates to support the state preserving mechanism for
     'sleeping' spin- and rwlocks on RT.

     This mechanism is carefully preserving the state of the task when
     blocking on a 'sleeping' spin- or rwlock and takes regular wake-ups
     targeted at the same task into account. The preserved or updated
     (via a regular wakeup) state is restored when the lock has been
     acquired.

   - Restructuring of the rtmutex code so it can be utilized and
     extended for the RT specific lock variants.

   - Restructuring of the ww_mutex code to allow sharing of the ww_mutex
     specific functionality for rtmutex based ww_mutexes.

   - Header file disentangling to allow substitution of the regular lock
     implementations with the PREEMPT_RT variants without creating an
     unmaintainable #ifdef mess.

   - Shared base code for the PREEMPT_RT specific rw_semaphore and
     rwlock implementations.

     Contrary to the regular rw_semaphores and rwlocks the PREEMPT_RT
     implementation is writer unfair because it is infeasible to do
     priority inheritance on multiple readers. Experience over the years
     has shown that real-time workloads are not the typical workloads
     which are sensitive to writer starvation.

     The alternative solution would be to allow only a single reader
     which has been tried and discarded as it is a major bottleneck
     especially for mmap_sem. Aside of that many of the writer
     starvation critical usage sites have been converted to a writer
     side mutex/spinlock and RCU read side protections in the past
     decade so that the issue is less prominent than it used to be.

   - The actual rtmutex based lock substitutions for PREEMPT_RT enabled
     kernels which affect mutex, ww_mutex, rw_semaphore, spinlock_t and
     rwlock_t. The spin/rw_lock*() functions disable migration across
     the critical section to preserve the existing semantics vs per-CPU
     variables.

   - Rework of the futex REQUEUE_PI mechanism to handle the case of
     early wake-ups which interleave with a re-queue operation to
     prevent the situation that a task would be blocked on both the
     rtmutex associated to the outer futex and the rtmutex based hash
     bucket spinlock.

     While this situation cannot happen on !RT enabled kernels the
     changes make the underlying concurrency problems easier to
     understand in general. As a result the difference between !RT and
     RT kernels is reduced to the handling of waiting for the critical
     section. !RT kernels simply spin-wait as before and RT kernels
     utilize rcu_wait().

   - The substitution of local_lock for PREEMPT_RT with a spinlock which
     protects the critical section while staying preemptible. The CPU
     locality is established by disabling migration.

  The underlying concepts of this code have been in use in PREEMPT_RT for
  way more than a decade. The code has been refactored several times over
  the years and this final incarnation has been optimized once again to be
  as non-intrusive as possible, i.e. the RT specific parts are mostly
  isolated.

  It has been extensively tested in the 5.14-rt patch series and it has
  been verified that !RT kernels are not affected by these changes"

* tag 'locking-core-2021-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (92 commits)
  locking/rtmutex: Return success on deadlock for ww_mutex waiters
  locking/rtmutex: Prevent spurious EDEADLK return caused by ww_mutexes
  locking/rtmutex: Dequeue waiter on ww_mutex deadlock
  locking/rtmutex: Dont dereference waiter lockless
  locking/semaphore: Add might_sleep() to down_*() family
  locking/ww_mutex: Initialize waiter.ww_ctx properly
  static_call: Update API documentation
  locking/local_lock: Add PREEMPT_RT support
  locking/spinlock/rt: Prepare for RT local_lock
  locking/rtmutex: Add adaptive spinwait mechanism
  locking/rtmutex: Implement equal priority lock stealing
  preempt: Adjust PREEMPT_LOCK_OFFSET for RT
  locking/rtmutex: Prevent lockdep false positive with PI futexes
  futex: Prevent requeue_pi() lock nesting issue on RT
  futex: Simplify handle_early_requeue_pi_wakeup()
  futex: Reorder sanity checks in futex_requeue()
  futex: Clarify comment in futex_requeue()
  futex: Restructure futex_requeue()
  futex: Correct the number of requeued waiters for PI
  futex: Remove bogus condition for requeue PI
  ...
2021-08-30 14:26:36 -07:00
Linus Torvalds
5d3c0db459 Scheduler changes for v5.15 are:
- The biggest change in this cycle is scheduler support for asymmetric
   scheduling affinity, to support the execution of legacy 32-bit tasks on
   AArch32 systems that also have 64-bit-only CPUs.
 
   Architectures can fill in this functionality by defining their
   own task_cpu_possible_mask(p). When this is done, the scheduler will
   make sure the task will only be scheduled on CPUs that support it.
 
   (The actual arm64 specific changes are not part of this tree.)
 
   For other architectures there will be no change in functionality.
 
 - Add cgroup SCHED_IDLE support
 
 - Increase node-distance flexibility & delay determining it until a CPU
   is brought online. (This enables platforms where node distance isn't
   final until the CPU is only.)
 
 - Deadline scheduler enhancements & fixes
 
 - Misc fixes & cleanups.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2021-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:

 - The biggest change in this cycle is scheduler support for asymmetric
   scheduling affinity, to support the execution of legacy 32-bit tasks
   on AArch32 systems that also have 64-bit-only CPUs.

   Architectures can fill in this functionality by defining their own
   task_cpu_possible_mask(p). When this is done, the scheduler will make
   sure the task will only be scheduled on CPUs that support it.

   (The actual arm64 specific changes are not part of this tree.)

   For other architectures there will be no change in functionality.

 - Add cgroup SCHED_IDLE support

 - Increase node-distance flexibility & delay determining it until a CPU
   is brought online. (This enables platforms where node distance isn't
   final until the CPU is only.)

 - Deadline scheduler enhancements & fixes

 - Misc fixes & cleanups.

* tag 'sched-core-2021-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
  eventfd: Make signal recursion protection a task bit
  sched/fair: Mark tg_is_idle() an inline in the !CONFIG_FAIR_GROUP_SCHED case
  sched: Introduce dl_task_check_affinity() to check proposed affinity
  sched: Allow task CPU affinity to be restricted on asymmetric systems
  sched: Split the guts of sched_setaffinity() into a helper function
  sched: Introduce task_struct::user_cpus_ptr to track requested affinity
  sched: Reject CPU affinity changes based on task_cpu_possible_mask()
  cpuset: Cleanup cpuset_cpus_allowed_fallback() use in select_fallback_rq()
  cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus()
  cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1
  sched: Introduce task_cpu_possible_mask() to limit fallback rq selection
  sched: Cgroup SCHED_IDLE support
  sched/topology: Skip updating masks for non-online nodes
  sched: Replace deprecated CPU-hotplug functions.
  sched: Skip priority checks with SCHED_FLAG_KEEP_PARAMS
  sched: Fix UCLAMP_FLAG_IDLE setting
  sched/deadline: Fix missing clock update in migrate_task_rq_dl()
  sched/fair: Avoid a second scan of target in select_idle_cpu
  sched/fair: Use prev instead of new target as recent_used_cpu
  sched: Don't report SCHED_FLAG_SUGOV in sched_getattr()
  ...
2021-08-30 13:42:10 -07:00
Eric W. Biederman
307d522f5e signal/seccomp: Refactor seccomp signal and coredump generation
Factor out force_sig_seccomp from the seccomp signal generation and
place it in kernel/signal.c.  The function force_sig_seccomp takes a
parameter force_coredump to indicate that the sigaction field should
be reset to SIGDFL so that a coredump will be generated when the
signal is delivered.

force_sig_seccomp is then used to replace both seccomp_send_sigsys
and seccomp_init_siginfo.

force_sig_info_to_task gains an extra parameter to force using
the default signal action.

With this change seccomp is no longer a special case and there
becomes exactly one place do_coredump is called from.

Further it no longer becomes necessary for __seccomp_filter
to call do_group_exit.

Acked-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/87r1gr6qc4.fsf_-_@disp2133
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-08-26 10:30:12 -05:00
Thomas Gleixner
2c8bb85151 sched/wake_q: Provide WAKE_Q_HEAD_INITIALIZER()
The RT specific spin/rwlock implementation requires special handling of the
to be woken waiters. Provide a WAKE_Q_HEAD_INITIALIZER(), which can be used by
the rtmutex code to implement an RT aware wake_q derivative.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211302.429918071@linutronix.de
2021-08-17 16:57:55 +02:00
Frederic Weisbecker
a5dec9f82a posix-cpu-timers: Assert task sighand is locked while starting cputime counter
Starting the process wide cputime counter needs to be done in the same
sighand locking sequence than actually arming the related timer otherwise
this races against concurrent timers setting/expiring in the same
threadgroup.

Detecting that the cputime counter is started without holding the sighand
lock is a first step toward debugging such situations.

Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210726125513.271824-2-frederic@kernel.org
2021-08-10 17:09:58 +02:00