Commit graph

1216 commits

Author SHA1 Message Date
Jakub Kicinski
c9d99cfa66 bpf-for-netdev
-----BEGIN PGP SIGNATURE-----
 
 iHUEABYIAB0WIQTFp0I1jqZrAX+hPRXbK58LschIgwUCZIDxUwAKCRDbK58LschI
 g5hDAQD7ukrniCvMRNIm2yUZIGSxE4RvGiXptO4a0NfLck5R/wEAsfN2KUsPcPhW
 HS37lVfx7VVXfj42+REf7lWLu4TXpwk=
 =6mS/
 -----END PGP SIGNATURE-----

Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
pull-request: bpf 2023-06-07

We've added 7 non-merge commits during the last 7 day(s) which contain
a total of 12 files changed, 112 insertions(+), 7 deletions(-).

The main changes are:

1) Fix a use-after-free in BPF's task local storage, from KP Singh.

2) Make struct path handling more robust in bpf_d_path, from Jiri Olsa.

3) Fix a syzbot NULL-pointer dereference in sockmap, from Eric Dumazet.

4) UAPI fix for BPF_NETFILTER before final kernel ships,
   from Florian Westphal.

5) Fix map-in-map array_map_gen_lookup code generation where elem_size was
   not being set for inner maps, from Rhys Rustad-Elliott.

6) Fix sockopt_sk selftest's NETLINK_LIST_MEMBERSHIPS assertion,
   from Yonghong Song.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  bpf: Add extra path pointer check to d_path helper
  selftests/bpf: Fix sockopt_sk selftest
  bpf: netfilter: Add BPF_NETFILTER bpf_attach_type
  selftests/bpf: Add access_inner_map selftest
  bpf: Fix elem_size not being set for inner maps
  bpf: Fix UAF in task local storage
  bpf, sockmap: Avoid potential NULL dereference in sk_psock_verdict_data_ready()
====================

Link: https://lore.kernel.org/r/20230607220514.29698-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-06-07 21:47:11 -07:00
KP Singh
b0fd1852bc bpf: Fix UAF in task local storage
When task local storage was generalized for tracing programs, the
bpf_task_local_storage callback was moved from a BPF LSM hook
callback for security_task_free LSM hook to it's own callback. But a
failure case in bad_fork_cleanup_security was missed which, when
triggered, led to a dangling task owner pointer and a subsequent
use-after-free. Move the bpf_task_storage_free to the very end of
free_task to handle all failure cases.

This issue was noticed when a BPF LSM program was attached to the
task_alloc hook on a kernel with KASAN enabled. The program used
bpf_task_storage_get to copy the task local storage from the current
task to the new task being created.

Fixes: a10787e6d5 ("bpf: Enable task local storage for tracing programs")
Reported-by: Kuba Piecuch <jpiecuch@google.com>
Signed-off-by: KP Singh <kpsingh@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230602002612.1117381-1-kpsingh@kernel.org
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
2023-06-02 10:18:07 -07:00
Mike Christie
f9010dbdce fork, vhost: Use CLONE_THREAD to fix freezer/ps regression
When switching from kthreads to vhost_tasks two bugs were added:
1. The vhost worker tasks's now show up as processes so scripts doing
ps or ps a would not incorrectly detect the vhost task as another
process.  2. kthreads disabled freeze by setting PF_NOFREEZE, but
vhost tasks's didn't disable or add support for them.

To fix both bugs, this switches the vhost task to be thread in the
process that does the VHOST_SET_OWNER ioctl, and has vhost_worker call
get_signal to support SIGKILL/SIGSTOP and freeze signals. Note that
SIGKILL/STOP support is required because CLONE_THREAD requires
CLONE_SIGHAND which requires those 2 signals to be supported.

This is a modified version of the patch written by Mike Christie
<michael.christie@oracle.com> which was a modified version of patch
originally written by Linus.

Much of what depended upon PF_IO_WORKER now depends on PF_USER_WORKER.
Including ignoring signals, setting up the register state, and having
get_signal return instead of calling do_group_exit.

Tidied up the vhost_task abstraction so that the definition of
vhost_task only needs to be visible inside of vhost_task.c.  Making
it easier to review the code and tell what needs to be done where.
As part of this the main loop has been moved from vhost_worker into
vhost_task_fn.  vhost_worker now returns true if work was done.

The main loop has been updated to call get_signal which handles
SIGSTOP, freezing, and collects the message that tells the thread to
exit as part of process exit.  This collection clears
__fatal_signal_pending.  This collection is not guaranteed to
clear signal_pending() so clear that explicitly so the schedule()
sleeps.

For now the vhost thread continues to exist and run work until the
last file descriptor is closed and the release function is called as
part of freeing struct file.  To avoid hangs in the coredump
rendezvous and when killing threads in a multi-threaded exec.  The
coredump code and de_thread have been modified to ignore vhost threads.

Remvoing the special case for exec appears to require teaching
vhost_dev_flush how to directly complete transactions in case
the vhost thread is no longer running.

Removing the special case for coredump rendezvous requires either the
above fix needed for exec or moving the coredump rendezvous into
get_signal.

Fixes: 6e890c5d50 ("vhost: use vhost_tasks for worker threads")
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Co-developed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-06-01 17:15:33 -04:00
Linus Torvalds
58390c8ce1 IOMMU Updates for Linux 6.4
Including:
 
 	- Convert to platform remove callback returning void
 
 	- Extend changing default domain to normal group
 
 	- Intel VT-d updates:
 	    - Remove VT-d virtual command interface and IOASID
 	    - Allow the VT-d driver to support non-PRI IOPF
 	    - Remove PASID supervisor request support
 	    - Various small and misc cleanups
 
 	- ARM SMMU updates:
 	    - Device-tree binding updates:
 	        * Allow Qualcomm GPU SMMUs to accept relevant clock properties
 	        * Document Qualcomm 8550 SoC as implementing an MMU-500
 	        * Favour new "qcom,smmu-500" binding for Adreno SMMUs
 
 	    - Fix S2CR quirk detection on non-architectural Qualcomm SMMU
 	      implementations
 
 	    - Acknowledge SMMUv3 PRI queue overflow when consuming events
 
 	    - Document (in a comment) why ATS is disabled for bypass streams
 
 	- AMD IOMMU updates:
 	    - 5-level page-table support
 	    - NUMA awareness for memory allocations
 
 	- Unisoc driver: Support for reattaching an existing domain
 
 	- Rockchip driver: Add missing set_platform_dma_ops callback
 
 	- Mediatek driver: Adjust the dma-ranges
 
 	- Various other small fixes and cleanups
 -----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCAAdFiEEr9jSbILcajRFYWYyK/BELZcBGuMFAmRONeAACgkQK/BELZcB
 GuPmpw/8C9ruxQ0JU5rcDBXQGvos4gMmxlbELMrBpbbiTtdb35xchpKfdhnECGIF
 k2SrrcF40R/S82SyzNU/eZtGKirtcXvGFraUFgu/QdCcnnqpRHs+IJMXX2NJP+it
 +0wO1uiInt3CN1ERcR4F31cDKiWjDG8bvQVE5LIyiy4KrIU5ld2G91Fkaa0R13Au
 6H+/wKkcUC6OyaGE6wPx474xBkapT20vj5AIQuAWisXJJR0wbBon1sUTo/IRKsU+
 IkNxH0W+1PNImJ+crAdf/nkOlyqoChY4ww6cm07LrOsBLIsX5bCqXfL4HvKthElD
 MEgk2SN5kfjfR5Vf29W4hZVM1CT8VbhO41I7OzaZ6X6RU2PXoldPKlgKtZGeSKn1
 9bcMpSgB0BtbttvBevSkxTo5KHFozXS2DG3DFoMB3yFMme8Th0LrhBZ9oB7NIPNw
 ntMo4K75vviC6Vvzjy4Anj/+y+Zm3W6wDDP7F12O6WZLkK5s4hrSsHUm/MQnnKQP
 muJlG870RnSl73xUQZe3cuBxktXuJ3EHqqYIPE0npzvauu8hhWcis3opf2Y+U2s8
 aBCCIgp5kTKqjHLh2e4lNCKZf1/b/dhxRcRBQhpAIb8YsjMlIJyM+G8Jz6K6gBga
 5Ld+68UQ3oHJwoLV1HCFN8jbpQ9KZn1s9+h3yrYjRAcLNiFb3nU=
 =OvTo
 -----END PGP SIGNATURE-----

Merge tag 'iommu-updates-v6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu

Pull iommu updates from Joerg Roedel:

 - Convert to platform remove callback returning void

 - Extend changing default domain to normal group

 - Intel VT-d updates:
     - Remove VT-d virtual command interface and IOASID
     - Allow the VT-d driver to support non-PRI IOPF
     - Remove PASID supervisor request support
     - Various small and misc cleanups

 - ARM SMMU updates:
     - Device-tree binding updates:
         * Allow Qualcomm GPU SMMUs to accept relevant clock properties
         * Document Qualcomm 8550 SoC as implementing an MMU-500
         * Favour new "qcom,smmu-500" binding for Adreno SMMUs

     - Fix S2CR quirk detection on non-architectural Qualcomm SMMU
       implementations

     - Acknowledge SMMUv3 PRI queue overflow when consuming events

     - Document (in a comment) why ATS is disabled for bypass streams

 - AMD IOMMU updates:
     - 5-level page-table support
     - NUMA awareness for memory allocations

 - Unisoc driver: Support for reattaching an existing domain

 - Rockchip driver: Add missing set_platform_dma_ops callback

 - Mediatek driver: Adjust the dma-ranges

 - Various other small fixes and cleanups

* tag 'iommu-updates-v6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu: (82 commits)
  iommu: Remove iommu_group_get_by_id()
  iommu: Make iommu_release_device() static
  iommu/vt-d: Remove BUG_ON in dmar_insert_dev_scope()
  iommu/vt-d: Remove a useless BUG_ON(dev->is_virtfn)
  iommu/vt-d: Remove BUG_ON in map/unmap()
  iommu/vt-d: Remove BUG_ON when domain->pgd is NULL
  iommu/vt-d: Remove BUG_ON in handling iotlb cache invalidation
  iommu/vt-d: Remove BUG_ON on checking valid pfn range
  iommu/vt-d: Make size of operands same in bitwise operations
  iommu/vt-d: Remove PASID supervisor request support
  iommu/vt-d: Use non-privileged mode for all PASIDs
  iommu/vt-d: Remove extern from function prototypes
  iommu/vt-d: Do not use GFP_ATOMIC when not needed
  iommu/vt-d: Remove unnecessary checks in iopf disabling path
  iommu/vt-d: Move PRI handling to IOPF feature path
  iommu/vt-d: Move pfsid and ats_qdep calculation to device probe path
  iommu/vt-d: Move iopf code from SVA to IOPF enabling path
  iommu/vt-d: Allow SVA with device-specific IOPF
  dmaengine: idxd: Add enable/disable device IOPF feature
  arm64: dts: mt8186: Add dma-ranges for the parent "soc" node
  ...
2023-04-30 13:00:38 -07:00
Linus Torvalds
d579c468d7 tracing updates for 6.4:
- User events are finally ready!
   After lots of collaboration between various parties, we finally locked
   down on a stable interface for user events that can also work with user
   space only tracing. This is implemented by telling the kernel (or user
   space library, but that part is user space only and not part of this
   patch set), where the variable is that the application uses to know if
   something is listening to the trace. There's also an interface to tell
   the kernel about these events, which will show up in the
   /sys/kernel/tracing/events/user_events/ directory, where it can be
    enabled. When it's enabled, the kernel will update the variable, to tell
   the application to start writing to the kernel.
   See https://lwn.net/Articles/927595/
 
 - Cleaned up the direct trampolines code to simplify arm64 addition of
   direct trampolines. Direct trampolines use the ftrace interface but
   instead of jumping to the ftrace trampoline, applications (mostly BPF)
   can register their own trampoline for performance reasons.
 
 - Some updates to the fprobe infrastructure. fprobes are more efficient than
   kprobes, as it does not need to save all the registers that kprobes on
   ftrace do. More work needs to be done before the fprobes will be exposed
   as dynamic events.
 
 - More updates to references to the obsolete path of
   /sys/kernel/debug/tracing for the new /sys/kernel/tracing path.
 
 - Add a seq_buf_do_printk() helper to seq_bufs, to print a large buffer line
   by line instead of all at once. There's users in production kernels that
   have a large data dump that originally used printk() directly, but the
   data dump was larger than what printk() allowed as a single print.
   Using seq_buf() to do the printing fixes that.
 
 - Add /sys/kernel/tracing/touched_functions that shows all functions that
   was every traced by ftrace or a direct trampoline. This is used for
   debugging issues where a traced function could have caused a crash by
   a bpf program or live patching.
 
 - Add a "fields" option that is similar to "raw" but outputs the fields of
   the events. It's easier to read by humans.
 
 - Some minor fixes and clean ups.
 -----BEGIN PGP SIGNATURE-----
 
 iIoEABYIADIWIQRRSw7ePDh/lE+zeZMp5XQQmuv6qgUCZEr36xQccm9zdGVkdEBn
 b29kbWlzLm9yZwAKCRAp5XQQmuv6quZHAQCzuqnn2S8DsPd3Sy1vKIYaj0uajW5D
 Kz1oUJH4F0H7kgEA8XwXkdtfKpOXWc/ZH4LWfL7Orx2wJZJQMV9dVqEPDAE=
 =w0Z1
 -----END PGP SIGNATURE-----

Merge tag 'trace-v6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing updates from Steven Rostedt:

 - User events are finally ready!

   After lots of collaboration between various parties, we finally
   locked down on a stable interface for user events that can also work
   with user space only tracing.

   This is implemented by telling the kernel (or user space library, but
   that part is user space only and not part of this patch set), where
   the variable is that the application uses to know if something is
   listening to the trace.

   There's also an interface to tell the kernel about these events,
   which will show up in the /sys/kernel/tracing/events/user_events/
   directory, where it can be enabled.

   When it's enabled, the kernel will update the variable, to tell the
   application to start writing to the kernel.

   See https://lwn.net/Articles/927595/

 - Cleaned up the direct trampolines code to simplify arm64 addition of
   direct trampolines.

   Direct trampolines use the ftrace interface but instead of jumping to
   the ftrace trampoline, applications (mostly BPF) can register their
   own trampoline for performance reasons.

 - Some updates to the fprobe infrastructure. fprobes are more efficient
   than kprobes, as it does not need to save all the registers that
   kprobes on ftrace do. More work needs to be done before the fprobes
   will be exposed as dynamic events.

 - More updates to references to the obsolete path of
   /sys/kernel/debug/tracing for the new /sys/kernel/tracing path.

 - Add a seq_buf_do_printk() helper to seq_bufs, to print a large buffer
   line by line instead of all at once.

   There are users in production kernels that have a large data dump
   that originally used printk() directly, but the data dump was larger
   than what printk() allowed as a single print.

   Using seq_buf() to do the printing fixes that.

 - Add /sys/kernel/tracing/touched_functions that shows all functions
   that was every traced by ftrace or a direct trampoline. This is used
   for debugging issues where a traced function could have caused a
   crash by a bpf program or live patching.

 - Add a "fields" option that is similar to "raw" but outputs the fields
   of the events. It's easier to read by humans.

 - Some minor fixes and clean ups.

* tag 'trace-v6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (41 commits)
  ring-buffer: Sync IRQ works before buffer destruction
  tracing: Add missing spaces in trace_print_hex_seq()
  ring-buffer: Ensure proper resetting of atomic variables in ring_buffer_reset_online_cpus
  recordmcount: Fix memory leaks in the uwrite function
  tracing/user_events: Limit max fault-in attempts
  tracing/user_events: Prevent same address and bit per process
  tracing/user_events: Ensure bit is cleared on unregister
  tracing/user_events: Ensure write index cannot be negative
  seq_buf: Add seq_buf_do_printk() helper
  tracing: Fix print_fields() for __dyn_loc/__rel_loc
  tracing/user_events: Set event filter_type from type
  ring-buffer: Clearly check null ptr returned by rb_set_head_page()
  tracing: Unbreak user events
  tracing/user_events: Use print_format_fields() for trace output
  tracing/user_events: Align structs with tabs for readability
  tracing/user_events: Limit global user_event count
  tracing/user_events: Charge event allocs to cgroups
  tracing/user_events: Update documentation for ABI
  tracing/user_events: Use write ABI in example
  tracing/user_events: Add ABI self-test
  ...
2023-04-28 15:57:53 -07:00
Linus Torvalds
586b222d74 Scheduler changes for v6.4:
- Allow unprivileged PSI poll()ing
 
  - Fix performance regression introduced by mm_cid
 
  - Improve livepatch stalls by adding livepatch task switching to cond_resched(),
    this resolves livepatching busy-loop stalls with certain CPU-bound kthreads.
 
  - Improve sched_move_task() performance on autogroup configs.
 
  - On core-scheduling CPUs, avoid selecting throttled tasks to run
 
  - Misc cleanups, fixes and improvements.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
 -----BEGIN PGP SIGNATURE-----
 
 iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAmRK39cRHG1pbmdvQGtl
 cm5lbC5vcmcACgkQEnMQ0APhK1hXPhAAk2WqOV2cW4BjSCHjWWE05IfTb0HMn8si
 mFGBAnr1GIkJRvICAusAwDU3FcmP5mWyXA+LK110d3x4fKJP15vCD5ru5lHnBfX7
 fSD+Ml8uM4Xlp8iUoQspilbQwmWkQSwhudbDs3Nj7XGUzJCvNgm1sM3xPRDlqSJ5
 6zumfVOPTfzSGcZY3a8sMuJnCepZHLRR6NkLzo/DuI1NMy2Jw1dK43dh77AO1mBF
 M53PF2IQgm6Wu/67p2k5eDq4c0AKL4PyIb4dRTGOPyljWMf41n28jwMv1tjlvu+Y
 uT0JD8MJSrFiylyT41x7Asr7orAGXj3cPhShK5R0vrutx/SbqBiaaE1MO9U3aC3B
 7xVXEORHWD6KIDqTvzmWGrMBkIdyWB6CLk6EJKr3MqM9hUtP2ift7bkAgIad9h+4
 G9DdVePGoCyh/TQtJ9EPIULAYeu9mmDZe8rTQ8C5MCSg//05/CTMgBbb0NiFWhnd
 0JQl1B0nNUA87whVUxK8Hfu4DLh7m9jrzgQr9Ww8/FwQ6tQHBOKWgDdbv45ckkaG
 cJIQt/+vLilddazc8u8E+BGaD5w2uIYF0uL7kvG6Q5oARX06AZ5dj1m06vhZe/Ym
 laOVZEpJsbQnxviY6jwj1n+CSB9aK7feiQfDePBPbpJGGUHyZoKrnLN6wmW2se+H
 VCHtdgsEl5I=
 =Hgci
 -----END PGP SIGNATURE-----

Merge tag 'sched-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:

 - Allow unprivileged PSI poll()ing

 - Fix performance regression introduced by mm_cid

 - Improve livepatch stalls by adding livepatch task switching to
   cond_resched(). This resolves livepatching busy-loop stalls with
   certain CPU-bound kthreads

 - Improve sched_move_task() performance on autogroup configs

 - On core-scheduling CPUs, avoid selecting throttled tasks to run

 - Misc cleanups, fixes and improvements

* tag 'sched-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/clock: Fix local_clock() before sched_clock_init()
  sched/rt: Fix bad task migration for rt tasks
  sched: Fix performance regression introduced by mm_cid
  sched/core: Make sched_dynamic_mutex static
  sched/psi: Allow unprivileged polling of N*2s period
  sched/psi: Extract update_triggers side effect
  sched/psi: Rename existing poll members in preparation
  sched/psi: Rearrange polling code in preparation
  sched/fair: Fix inaccurate tally of ttwu_move_affine
  vhost: Fix livepatch timeouts in vhost_worker()
  livepatch,sched: Add livepatch task switching to cond_resched()
  livepatch: Skip task_call_func() for current task
  livepatch: Convert stack entries array to percpu
  sched: Interleave cfs bandwidth timers for improved single thread performance at low utilization
  sched/core: Reduce cost of sched_move_task when config autogroup
  sched/core: Avoid selecting the task that is throttled to run when core-sched enable
  sched/topology: Make sched_energy_mutex,update static
2023-04-28 14:53:30 -07:00
Linus Torvalds
7fa8a8ee94 - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of
switching from a user process to a kernel thread.
 
 - More folio conversions from Kefeng Wang, Zhang Peng and Pankaj Raghav.
 
 - zsmalloc performance improvements from Sergey Senozhatsky.
 
 - Yue Zhao has found and fixed some data race issues around the
   alteration of memcg userspace tunables.
 
 - VFS rationalizations from Christoph Hellwig:
 
   - removal of most of the callers of write_one_page().
 
   - make __filemap_get_folio()'s return value more useful
 
 - Luis Chamberlain has changed tmpfs so it no longer requires swap
   backing.  Use `mount -o noswap'.
 
 - Qi Zheng has made the slab shrinkers operate locklessly, providing
   some scalability benefits.
 
 - Keith Busch has improved dmapool's performance, making part of its
   operations O(1) rather than O(n).
 
 - Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd,
   permitting userspace to wr-protect anon memory unpopulated ptes.
 
 - Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive rather
   than exclusive, and has fixed a bunch of errors which were caused by its
   unintuitive meaning.
 
 - Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature,
   which causes minor faults to install a write-protected pte.
 
 - Vlastimil Babka has done some maintenance work on vma_merge():
   cleanups to the kernel code and improvements to our userspace test
   harness.
 
 - Cleanups to do_fault_around() by Lorenzo Stoakes.
 
 - Mike Rapoport has moved a lot of initialization code out of various
   mm/ files and into mm/mm_init.c.
 
 - Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for
   DRM, but DRM doesn't use it any more.
 
 - Lorenzo has also coverted read_kcore() and vread() to use iterators
   and has thereby removed the use of bounce buffers in some cases.
 
 - Lorenzo has also contributed further cleanups of vma_merge().
 
 - Chaitanya Prakash provides some fixes to the mmap selftesting code.
 
 - Matthew Wilcox changes xfs and afs so they no longer take sleeping
   locks in ->map_page(), a step towards RCUification of pagefaults.
 
 - Suren Baghdasaryan has improved mmap_lock scalability by switching to
   per-VMA locking.
 
 - Frederic Weisbecker has reworked the percpu cache draining so that it
   no longer causes latency glitches on cpu isolated workloads.
 
 - Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig
   logic.
 
 - Liu Shixin has changed zswap's initialization so we no longer waste a
   chunk of memory if zswap is not being used.
 
 - Yosry Ahmed has improved the performance of memcg statistics flushing.
 
 - David Stevens has fixed several issues involving khugepaged,
   userfaultfd and shmem.
 
 - Christoph Hellwig has provided some cleanup work to zram's IO-related
   code paths.
 
 - David Hildenbrand has fixed up some issues in the selftest code's
   testing of our pte state changing.
 
 - Pankaj Raghav has made page_endio() unneeded and has removed it.
 
 - Peter Xu contributed some rationalizations of the userfaultfd
   selftests.
 
 - Yosry Ahmed has fixed an issue around memcg's page recalim accounting.
 
 - Chaitanya Prakash has fixed some arm-related issues in the
   selftests/mm code.
 
 - Longlong Xia has improved the way in which KSM handles hwpoisoned
   pages.
 
 - Peter Xu fixes a few issues with uffd-wp at fork() time.
 
 - Stefan Roesch has changed KSM so that it may now be used on a
   per-process and per-cgroup basis.
 -----BEGIN PGP SIGNATURE-----
 
 iHUEABYIAB0WIQTTMBEPP41GrTpTJgfdBJ7gKXxAjgUCZEr3zQAKCRDdBJ7gKXxA
 jlLoAP0fpQBipwFxED0Us4SKQfupV6z4caXNJGPeay7Aj11/kQD/aMRC2uPfgr96
 eMG3kwn2pqkB9ST2QpkaRbxA//eMbQY=
 =J+Dj
 -----END PGP SIGNATURE-----

Merge tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of
   switching from a user process to a kernel thread.

 - More folio conversions from Kefeng Wang, Zhang Peng and Pankaj
   Raghav.

 - zsmalloc performance improvements from Sergey Senozhatsky.

 - Yue Zhao has found and fixed some data race issues around the
   alteration of memcg userspace tunables.

 - VFS rationalizations from Christoph Hellwig:
     - removal of most of the callers of write_one_page()
     - make __filemap_get_folio()'s return value more useful

 - Luis Chamberlain has changed tmpfs so it no longer requires swap
   backing. Use `mount -o noswap'.

 - Qi Zheng has made the slab shrinkers operate locklessly, providing
   some scalability benefits.

 - Keith Busch has improved dmapool's performance, making part of its
   operations O(1) rather than O(n).

 - Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd,
   permitting userspace to wr-protect anon memory unpopulated ptes.

 - Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive
   rather than exclusive, and has fixed a bunch of errors which were
   caused by its unintuitive meaning.

 - Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature,
   which causes minor faults to install a write-protected pte.

 - Vlastimil Babka has done some maintenance work on vma_merge():
   cleanups to the kernel code and improvements to our userspace test
   harness.

 - Cleanups to do_fault_around() by Lorenzo Stoakes.

 - Mike Rapoport has moved a lot of initialization code out of various
   mm/ files and into mm/mm_init.c.

 - Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for
   DRM, but DRM doesn't use it any more.

 - Lorenzo has also coverted read_kcore() and vread() to use iterators
   and has thereby removed the use of bounce buffers in some cases.

 - Lorenzo has also contributed further cleanups of vma_merge().

 - Chaitanya Prakash provides some fixes to the mmap selftesting code.

 - Matthew Wilcox changes xfs and afs so they no longer take sleeping
   locks in ->map_page(), a step towards RCUification of pagefaults.

 - Suren Baghdasaryan has improved mmap_lock scalability by switching to
   per-VMA locking.

 - Frederic Weisbecker has reworked the percpu cache draining so that it
   no longer causes latency glitches on cpu isolated workloads.

 - Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig
   logic.

 - Liu Shixin has changed zswap's initialization so we no longer waste a
   chunk of memory if zswap is not being used.

 - Yosry Ahmed has improved the performance of memcg statistics
   flushing.

 - David Stevens has fixed several issues involving khugepaged,
   userfaultfd and shmem.

 - Christoph Hellwig has provided some cleanup work to zram's IO-related
   code paths.

 - David Hildenbrand has fixed up some issues in the selftest code's
   testing of our pte state changing.

 - Pankaj Raghav has made page_endio() unneeded and has removed it.

 - Peter Xu contributed some rationalizations of the userfaultfd
   selftests.

 - Yosry Ahmed has fixed an issue around memcg's page recalim
   accounting.

 - Chaitanya Prakash has fixed some arm-related issues in the
   selftests/mm code.

 - Longlong Xia has improved the way in which KSM handles hwpoisoned
   pages.

 - Peter Xu fixes a few issues with uffd-wp at fork() time.

 - Stefan Roesch has changed KSM so that it may now be used on a
   per-process and per-cgroup basis.

* tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits)
  mm,unmap: avoid flushing TLB in batch if PTE is inaccessible
  shmem: restrict noswap option to initial user namespace
  mm/khugepaged: fix conflicting mods to collapse_file()
  sparse: remove unnecessary 0 values from rc
  mm: move 'mmap_min_addr' logic from callers into vm_unmapped_area()
  hugetlb: pte_alloc_huge() to replace huge pte_alloc_map()
  maple_tree: fix allocation in mas_sparse_area()
  mm: do not increment pgfault stats when page fault handler retries
  zsmalloc: allow only one active pool compaction context
  selftests/mm: add new selftests for KSM
  mm: add new KSM process and sysfs knobs
  mm: add new api to enable ksm per process
  mm: shrinkers: fix debugfs file permissions
  mm: don't check VMA write permissions if the PTE/PMD indicates write permissions
  migrate_pages_batch: fix statistics for longterm pin retry
  userfaultfd: use helper function range_in_vma()
  lib/show_mem.c: use for_each_populated_zone() simplify code
  mm: correct arg in reclaim_pages()/reclaim_clean_pages_from_list()
  fs/buffer: convert create_page_buffers to folio_create_buffers
  fs/buffer: add folio_create_empty_buffers helper
  ...
2023-04-27 19:42:02 -07:00
Linus Torvalds
ec40758b31 v6.4/pidfd.file
-----BEGIN PGP SIGNATURE-----
 
 iHUEABYKAB0WIQRAhzRXHqcMeLMyaSiRxhvAZXjcogUCZEEt8gAKCRCRxhvAZXjc
 oppuAQDu9kwAQWAl0KzlpjQkrEDAEuyHRy6SCpo1kPPD5f3rigD+INZb3fi2QXmK
 ZL/c6XtII9ah/8i2zfzAgH9Q2ZZu0gk=
 =xcAX
 -----END PGP SIGNATURE-----

Merge tag 'v6.4/pidfd.file' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

Pull pidfd updates from Christian Brauner:
 "This adds a new pidfd_prepare() helper which allows the caller to
  reserve a pidfd number and allocates a new pidfd file that stashes the
  provided struct pid.

  It should be avoided installing a file descriptor into a task's file
  descriptor table just to close it again via close_fd() in case an
  error occurs. The fd has been visible to userspace and might already
  be in use. Instead, a file descriptor should be reserved but not
  installed into the caller's file descriptor table.

  If another failure path is hit then the reserved file descriptor and
  file can just be put without any userspace visible side-effects. And
  if all failure paths are cleared the file descriptor and file can be
  installed into the task's file descriptor table.

  This helper is now used in all places that open coded this
  functionality before. For example, this is currently done during
  copy_process() and fanotify used pidfd_create(), which returns a pidfd
  that has already been made visibile in the caller's file descriptor
  table, but then closed it using close_fd().

  In one of the next merge windows there is also new functionality
  coming to unix domain sockets that will have to rely on
  pidfd_prepare()"

* tag 'v6.4/pidfd.file' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  fanotify: use pidfd_prepare()
  fork: use pidfd_prepare()
  pid: add pidfd_prepare()
2023-04-24 13:03:42 -07:00
Linus Torvalds
3323ddce08 v6.4/kernel.user_worker
-----BEGIN PGP SIGNATURE-----
 
 iHUEABYKAB0WIQRAhzRXHqcMeLMyaSiRxhvAZXjcogUCZEEvmQAKCRCRxhvAZXjc
 omUmAP0YaHa0gGgC1HEqZUpr0wRCo9WCyDCIZh3CYHUsgSwtvAD/Skl3jeWPPhlm
 pmRA2DDxmwYFP3vhhFMjP+Z6AuUpEQQ=
 =9XpZ
 -----END PGP SIGNATURE-----

Merge tag 'v6.4/kernel.user_worker' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

Pull user work thread updates from Christian Brauner:
 "This contains the work generalizing the ability to create a kernel
  worker from a userspace process.

  Such user workers will run with the same credentials as the userspace
  process they were created from providing stronger security and
  accounting guarantees than the traditional override_creds() approach
  ever could've hoped for.

  The original work was heavily based and optimzed for the needs of
  io_uring which was the first user. However, as it quickly turned out
  the ability to create user workers inherting properties from a
  userspace process is generally useful.

  The vhost subsystem currently creates workers using the kthread api.
  The consequences of using the kthread api are that RLIMITs don't work
  correctly as they are inherited from khtreadd. This leads to bugs
  where more workers are created than would be allowed by the RLIMITs of
  the userspace process in lieu of which workers are created.

  Problems like this disappear with user workers created from the
  userspace processes for which they perform the work. In addition,
  providing this api allows vhost to remove additional complexity. For
  example, cgroup and mm sharing will just work out of the box with user
  workers based on the relevant userspace process instead of manually
  ensuring the correct cgroup and mm contexts are used.

  So the vhost subsystem should simply be made to use the same mechanism
  as io_uring. To this end the original mechanism used for
  create_io_thread() is generalized into user workers:

   - Introduce PF_USER_WORKER as a generic indicator that a given task
     is a user worker, i.e., a kernel task that was created from a
     userspace process. Now a PF_IO_WORKER thread is just a specialized
     version of PF_USER_WORKER. So io_uring io workers raise both flags.

   - Make copy_process() available to core kernel code

   - Extend struct kernel_clone_args with the following bitfields
     allowing to indicate to copy_process():
       - to create a user worker (raise PF_USER_WORKER)
       - to not inherit any files from the userspace process
       - to ignore signals

  After all generic changes are in place the vhost subsystem implements
  a new dedicated vhost api based on user workers. Finally, vhost is
  switched to rely on the new api moving it off of kthreads.

  Thanks to Mike for sticking it out and making it through this rather
  arduous journey"

* tag 'v6.4/kernel.user_worker' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  vhost: use vhost_tasks for worker threads
  vhost: move worker thread fields to new struct
  vhost_task: Allow vhost layer to use copy_process
  fork: allow kernel code to call copy_process
  fork: Add kernel_clone_args flag to ignore signals
  fork: add kernel_clone_args flag to not dup/clone files
  fork/vm: Move common PF_IO_WORKER behavior to new flag
  kernel: Make io_thread and kthread bit fields
  kthread: Pass in the thread's name during creation
  kernel: Allow a kernel thread's name to be set in copy_process
  csky: Remove kernel_thread declaration
2023-04-24 12:52:35 -07:00
Mathieu Desnoyers
223baf9d17 sched: Fix performance regression introduced by mm_cid
Introduce per-mm/cpu current concurrency id (mm_cid) to fix a PostgreSQL
sysbench regression reported by Aaron Lu.

Keep track of the currently allocated mm_cid for each mm/cpu rather than
freeing them immediately on context switch. This eliminates most atomic
operations when context switching back and forth between threads
belonging to different memory spaces in multi-threaded scenarios (many
processes, each with many threads). The per-mm/per-cpu mm_cid values are
serialized by their respective runqueue locks.

Thread migration is handled by introducing invocation to
sched_mm_cid_migrate_to() (with destination runqueue lock held) in
activate_task() for migrating tasks. If the destination cpu's mm_cid is
unset, and if the source runqueue is not actively using its mm_cid, then
the source cpu's mm_cid is moved to the destination cpu on migration.

Introduce a task-work executed periodically, similarly to NUMA work,
which delays reclaim of cid values when they are unused for a period of
time.

Keep track of the allocation time for each per-cpu cid, and let the task
work clear them when they are observed to be older than
SCHED_MM_CID_PERIOD_NS and unused. This task work also clears all
mm_cids which are greater or equal to the Hamming weight of the mm
cidmask to keep concurrency ids compact.

Because we want to ensure the mm_cid converges towards the smaller
values as migrations happen, the prior optimization that was done when
context switching between threads belonging to the same mm is removed,
because it could delay the lazy release of the destination runqueue
mm_cid after it has been replaced by a migration. Removing this prior
optimization is not an issue performance-wise because the introduced
per-mm/per-cpu mm_cid tracking also covers this more specific case.

Fixes: af7f588d8f ("sched: Introduce per-memory-map concurrency ID")
Reported-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Aaron Lu <aaron.lu@intel.com>
Link: https://lore.kernel.org/lkml/20230327080502.GA570847@ziqianlu-desk2/
2023-04-21 13:24:20 +02:00
Andrew Morton
f8f238ffe5 sync mm-stable with mm-hotfixes-stable to pick up depended-upon upstream changes 2023-04-18 14:53:49 -07:00
Mathieu Desnoyers
b20b0368c6 mm: fix memory leak on mm_init error handling
commit f1a7941243 ("mm: convert mm's rss stats into percpu_counter")
introduces a memory leak by missing a call to destroy_context() when a
percpu_counter fails to allocate.

Before introducing the per-cpu counter allocations, init_new_context() was
the last call that could fail in mm_init(), and thus there was no need to
ever invoke destroy_context() in the error paths.  Adding the following
percpu counter allocations adds error paths after init_new_context(),
which means its associated destroy_context() needs to be called when
percpu counters fail to allocate.

Link: https://lkml.kernel.org/r/20230330133822.66271-1-mathieu.desnoyers@efficios.com
Fixes: f1a7941243 ("mm: convert mm's rss stats into percpu_counter")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-18 14:22:12 -07:00
Andrew Morton
e492cd61b9 sync mm-stable with mm-hotfixes-stable to pick up depended-upon upstream changes 2023-04-16 12:31:58 -07:00
Joerg Roedel
e51b419839 Merge branches 'iommu/fixes', 'arm/allwinner', 'arm/exynos', 'arm/mediatek', 'arm/omap', 'arm/renesas', 'arm/rockchip', 'arm/smmu', 'ppc/pamu', 'unisoc', 'x86/vt-d', 'x86/amd', 'core' and 'platform-remove_new' into next 2023-04-14 13:45:50 +02:00
Mel Gorman
ef6a22b70f sched/numa: apply the scan delay to every new vma
Pach series "sched/numa: Enhance vma scanning", v3.

The patchset proposes one of the enhancements to numa vma scanning
suggested by Mel.  This is continuation of [3].

Reposting the rebased patchset to akpm mm-unstable tree (March 1) 

Existing mechanism of scan period involves, scan period derived from
per-thread stats.  Process Adaptive autoNUMA [1] proposed to gather NUMA
fault stats at per-process level to capture aplication behaviour better.

During that course of discussion, Mel proposed several ideas to enhance
current numa balancing.  One of the suggestion was below

Track what threads access a VMA.  The suggestion was to use an unsigned
long pid_mask and use the lower bits to tag approximately what threads
access a VMA.  Skip VMAs that did not trap a fault.  This would be
approximate because of PID collisions but would reduce scanning of areas
the thread is not interested in.  The above suggestion intends not to
penalize threads that has no interest in the vma, thus reduce scanning
overhead.

V3 changes are mostly based on PeterZ comments (details below in changes)

Summary of patchset:

Current patchset implements:

1. Delay the vma scanning logic for newly created VMA's so that
   additional overhead of scanning is not incurred for short lived tasks
   (implementation by Mel)

2. Store the information of tasks accessing VMA in 2 windows.  It is
   regularly cleared in (4*sysctl_numa_balancing_scan_delay) interval. 
   The above time is derived from experimenting (Suggested by PeterZ) to
   balance between frequent clearing vs obsolete access data

3. hash_32 used to encode task index accessing VMA information

4. VMA's acess information is used to skip scanning for the tasks
   which had not accessed VMA

Changes since V2:
patch1: 
 - Renaming of structure, macro to function,
 - Add explanation to heuristics
 - Adding more details from result (PeterZ)
 Patch2:
 - Usage of test and set bit (PeterZ)
 - Move storing access PID info to numa_migrate_prep()
 - Add a note on fainess among tasks allowed to scan
   (PeterZ)
 Patch3:
 - Maintain two windows of access PID information
  (PeterZ supported implementation and Gave idea to extend
   to N if needed)
 Patch4:
 - Apply hash_32 function to track VMA accessing PIDs (PeterZ)

Changes since RFC V1:
 - Include Mel's vma scan delay patch
 - Change the accessing pid store logic (Thanks Mel)
 - Fencing structure / code to NUMA_BALANCING (David, Mel)
 - Adding clearing access PID logic (Mel)
 - Descriptive change log ( Mike Rapoport)

Things to ponder over:
==========================================

- Improvement to clearing accessing PIDs logic (discussed in-detail in
  patch3 itself (Done in this patchset by implementing 2 window history)

- Current scan period is not changed in the patchset, so we do see
  frequent tries to scan.  Relaxing scan period dynamically could improve
  results further.

[1] sched/numa: Process Adaptive autoNUMA 
 Link: https://lore.kernel.org/lkml/20220128052851.17162-1-bharata@amd.com/T/

[2] RFC V1 Link: 
  https://lore.kernel.org/all/cover.1673610485.git.raghavendra.kt@amd.com/

[3] V2 Link:
  https://lore.kernel.org/lkml/cover.1675159422.git.raghavendra.kt@amd.com/


Results:
Summary: Huge autonuma cost reduction seen in mmtest. Kernbench improvement 
is more than 5% and huge system time (80%+) improvement from mmtest autonuma.
(dbench had huge std deviation to post)

kernbench
===========
                      6.2.0-mmunstable-base  6.2.0-mmunstable-patched
Amean     user-256    22002.51 (   0.00%)    22649.95 *  -2.94%*
Amean     syst-256    10162.78 (   0.00%)     8214.13 *  19.17%*
Amean     elsp-256      160.74 (   0.00%)      156.92 *   2.38%*

Duration User       66017.43    67959.84
Duration System     30503.15    24657.03
Duration Elapsed      504.61      493.12

                      6.2.0-mmunstable-base  6.2.0-mmunstable-patched
Ops NUMA alloc hit                1738835089.00  1738780310.00
Ops NUMA alloc local              1738834448.00  1738779711.00
Ops NUMA base-page range updates      477310.00      392566.00
Ops NUMA PTE updates                  477310.00      392566.00
Ops NUMA hint faults                   96817.00       87555.00
Ops NUMA hint local faults %           10150.00        2192.00
Ops NUMA hint local percent               10.48           2.50
Ops NUMA pages migrated                86660.00       85363.00
Ops AutoNUMA cost                        489.07         442.14

autonumabench
===============
                      6.2.0-mmunstable-base  6.2.0-mmunstable-patched
Amean     syst-NUMA01                  399.50 (   0.00%)       52.05 *  86.97%*
Amean     syst-NUMA01_THREADLOCAL        0.21 (   0.00%)        0.22 *  -5.41%*
Amean     syst-NUMA02                    0.80 (   0.00%)        0.78 *   2.68%*
Amean     syst-NUMA02_SMT                0.65 (   0.00%)        0.68 *  -3.95%*
Amean     elsp-NUMA01                  313.26 (   0.00%)      313.11 *   0.05%*
Amean     elsp-NUMA01_THREADLOCAL        1.06 (   0.00%)        1.08 *  -1.76%*
Amean     elsp-NUMA02                    3.19 (   0.00%)        3.24 *  -1.52%*
Amean     elsp-NUMA02_SMT                3.72 (   0.00%)        3.61 *   2.92%*

Duration User      396433.47   324835.96
Duration System      2808.70      376.66
Duration Elapsed     2258.61     2258.12

                      6.2.0-mmunstable-base  6.2.0-mmunstable-patched
Ops NUMA alloc hit                  59921806.00    49623489.00
Ops NUMA alloc miss                        0.00           0.00
Ops NUMA interleave hit                    0.00           0.00
Ops NUMA alloc local                59920880.00    49622594.00
Ops NUMA base-page range updates   152259275.00       50075.00
Ops NUMA PTE updates               152259275.00       50075.00
Ops NUMA PMD updates                       0.00           0.00
Ops NUMA hint faults               154660352.00       39014.00
Ops NUMA hint local faults %       138550501.00       23139.00
Ops NUMA hint local percent               89.58          59.31
Ops NUMA pages migrated              8179067.00       14147.00
Ops AutoNUMA cost                     774522.98         195.69


This patch (of 4):

Currently whenever a new task is created we wait for
sysctl_numa_balancing_scan_delay to avoid unnessary scanning overhead. 
Extend the same logic to new or very short-lived VMAs.

[raghavendra.kt@amd.com: add initialization in vm_area_dup())]
Link: https://lkml.kernel.org/r/cover.1677672277.git.raghavendra.kt@amd.com
Link: https://lkml.kernel.org/r/7a6fbba87c8b51e67efd3e74285bb4cb311a16ca.1677672277.git.raghavendra.kt@amd.com
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Raghavendra K T <raghavendra.kt@amd.com>
Cc: Bharata B Rao <bharata@amd.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Disha Talreja <dishaa.talreja@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-05 20:03:03 -07:00
Suren Baghdasaryan
c7f8f31c00 mm: separate vma->lock from vm_area_struct
vma->lock being part of the vm_area_struct causes performance regression
during page faults because during contention its count and owner fields
are constantly updated and having other parts of vm_area_struct used
during page fault handling next to them causes constant cache line
bouncing.  Fix that by moving the lock outside of the vm_area_struct.

All attempts to keep vma->lock inside vm_area_struct in a separate cache
line still produce performance regression especially on NUMA machines. 
Smallest regression was achieved when lock is placed in the fourth cache
line but that bloats vm_area_struct to 256 bytes.

Considering performance and memory impact, separate lock looks like the
best option.  It increases memory footprint of each VMA but that can be
optimized later if the new size causes issues.  Note that after this
change vma_init() does not allocate or initialize vma->lock anymore.  A
number of drivers allocate a pseudo VMA on the stack but they never use
the VMA's lock, therefore it does not need to be allocated.  The future
drivers which might need the VMA lock should use
vm_area_alloc()/vm_area_free() to allocate the VMA.

Link: https://lkml.kernel.org/r/20230227173632.3292573-34-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-05 20:03:02 -07:00
Suren Baghdasaryan
0d2ebf9c3f mm/mmap: free vm_area_struct without call_rcu in exit_mmap
call_rcu() can take a long time when callback offloading is enabled.  Its
use in the vm_area_free can cause regressions in the exit path when
multiple VMAs are being freed.

Because exit_mmap() is called only after the last mm user drops its
refcount, the page fault handlers can't be racing with it.  Any other
possible user like oom-reaper or process_mrelease are already synchronized
using mmap_lock.  Therefore exit_mmap() can free VMAs directly, without
the use of call_rcu().

Expose __vm_area_free() and use it from exit_mmap() to avoid possible
call_rcu() floods and performance regressions caused by it.

Link: https://lkml.kernel.org/r/20230227173632.3292573-33-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-05 20:03:02 -07:00
Suren Baghdasaryan
f2e13784c1 kernel/fork: assert no VMA readers during its destruction
Assert there are no holders of VMA lock for reading when it is about to be
destroyed.

Link: https://lkml.kernel.org/r/20230227173632.3292573-21-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-05 20:02:59 -07:00
Suren Baghdasaryan
5e31275cc9 mm: add per-VMA lock and helper functions to control it
Introduce per-VMA locking.  The lock implementation relies on a per-vma
and per-mm sequence counters to note exclusive locking:

  - read lock - (implemented by vma_start_read) requires the vma
    (vm_lock_seq) and mm (mm_lock_seq) sequence counters to differ.
    If they match then there must be a vma exclusive lock held somewhere.
  - read unlock - (implemented by vma_end_read) is a trivial vma->lock
    unlock.
  - write lock - (vma_start_write) requires the mmap_lock to be held
    exclusively and the current mm counter is assigned to the vma counter.
    This will allow multiple vmas to be locked under a single mmap_lock
    write lock (e.g. during vma merging). The vma counter is modified
    under exclusive vma lock.
  - write unlock - (vma_end_write_all) is a batch release of all vma
    locks held. It doesn't pair with a specific vma_start_write! It is
    done before exclusive mmap_lock is released by incrementing mm
    sequence counter (mm_lock_seq).
  - write downgrade - if the mmap_lock is downgraded to the read lock, all
    vma write locks are released as well (effectivelly same as write
    unlock).

Link: https://lkml.kernel.org/r/20230227173632.3292573-13-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-05 20:02:57 -07:00
Michel Lespinasse
20cce633f4 mm: rcu safe VMA freeing
This prepares for page faults handling under VMA lock, looking up VMAs
under protection of an rcu read lock, instead of the usual mmap read lock.

Link: https://lkml.kernel.org/r/20230227173632.3292573-11-surenb@google.com
Signed-off-by: Michel Lespinasse <michel@lespinasse.org>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-05 20:02:57 -07:00
Liam R. Howlett
3dd4432549 mm: enable maple tree RCU mode by default
Use the maple tree in RCU mode for VMA tracking.

The maple tree tracks the stack and is able to update the pivot
(lower/upper boundary) in-place to allow the page fault handler to write
to the tree while holding just the mmap read lock.  This is safe as the
writes to the stack have a guard VMA which ensures there will always be a
NULL in the direction of the growth and thus will only update a pivot.

It is possible, but not recommended, to have VMAs that grow up/down
without guard VMAs.  syzbot has constructed a testcase which sets up a VMA
to grow and consume the empty space.  Overwriting the entire NULL entry
causes the tree to be altered in a way that is not safe for concurrent
readers; the readers may see a node being rewritten or one that does not
match the maple state they are using.

Enabling RCU mode allows the concurrent readers to see a stable node and
will return the expected result.

[Liam.Howlett@Oracle.com: we don't need to free the nodes with RCU[
Link: https://lore.kernel.org/linux-mm/000000000000b0a65805f663ace6@google.com/
Link: https://lkml.kernel.org/r/20230227173632.3292573-9-surenb@google.com
Fixes: d4af56c5c7 ("mm: start tracking VMAs with maple tree")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reported-by: syzbot+8d95422d3537159ca390@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-05 18:06:22 -07:00
Christian Brauner
ca7707f543
fork: use pidfd_prepare()
Stop open-coding get_unused_fd_flags() and anon_inode_getfile(). That's
brittle just for keeping the flags between both calls in sync. Use the
dedicated helper.

Message-Id: <20230327-pidfd-file-api-v1-2-5c0e9a3158e4@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-04-03 11:16:57 +02:00
Christian Brauner
6ae930d9db
pid: add pidfd_prepare()
Add a new helper that allows to reserve a pidfd and allocates a new
pidfd file that stashes the provided struct pid. This will allow us to
remove places that either open code this function or that call
pidfd_create() but then have to call close_fd() because there are still
failure points after pidfd_create() has been called.

Reviewed-by: Jan Kara <jack@suse.cz>
Message-Id: <20230327-pidfd-file-api-v1-1-5c0e9a3158e4@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-04-03 11:16:56 +02:00
Jacob Pan
cd3891158a iommu/sva: Move PASID helpers to sva code
Preparing to remove IOASID infrastructure, PASID management will be
under SVA code. Decouple mm code from IOASID.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20230322200803.869130-3-jacob.jun.pan@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2023-03-31 10:03:23 +02:00
Beau Belgrave
fd593511cd tracing/user_events: Track fork/exec/exit for mm lifetime
During tracefs discussions it was decided instead of requiring a mapping
within a user-process to track the lifetime of memory descriptors we
should hook the appropriate calls. Do this by adding the minimal stubs
required for task fork, exec, and exit. Currently this is just a NOP.
Future patches will implement these calls fully.

Link: https://lkml.kernel.org/r/20230328235219.203-3-beaub@linux.microsoft.com

Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-03-29 06:52:08 -04:00
Nicholas Piggin
2655421ae6 lazy tlb: shoot lazies, non-refcounting lazy tlb mm reference handling scheme
On big systems, the mm refcount can become highly contented when doing a
lot of context switching with threaded applications.  user<->idle switch
is one of the important cases.  Abandoning lazy tlb entirely slows this
switching down quite a bit in the common uncontended case, so that is not
viable.

Implement a scheme where lazy tlb mm references do not contribute to the
refcount, instead they get explicitly removed when the refcount reaches
zero.

The final mmdrop() sends IPIs to all CPUs in the mm_cpumask and they
switch away from this mm to init_mm if it was being used as the lazy tlb
mm.  Enabling the shoot lazies option therefore requires that the arch
ensures that mm_cpumask contains all CPUs that could possibly be using mm.
A DEBUG_VM option IPIs every CPU in the system after this to ensure there
are no references remaining before the mm is freed.

Shootdown IPIs cost could be an issue, but they have not been observed to
be a serious problem with this scheme, because short-lived processes tend
not to migrate CPUs much, therefore they don't get much chance to leave
lazy tlb mm references on remote CPUs.  There are a lot of options to
reduce them if necessary, described in comments.

The near-worst-case can be benchmarked with will-it-scale:

  context_switch1_threads -t $(($(nproc) / 2))

This will create nproc threads (nproc / 2 switching pairs) all sharing the
same mm that spread over all CPUs so each CPU does thread->idle->thread
switching.

[ Rik came up with basically the same idea a few years ago, so credit
  to him for that. ]

Link: https://lore.kernel.org/linux-mm/20230118080011.2258375-1-npiggin@gmail.com/
Link: https://lore.kernel.org/all/20180728215357.3249-11-riel@surriel.com/
Link: https://lkml.kernel.org/r/20230203071837.1136453-5-npiggin@gmail.com
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-03-28 16:20:08 -07:00
Linus Torvalds
f768b35a23 Fixes for 6.3-rc3:
* Fix a race in the percpu counters summation code where the summation
    failed to add in the values for any CPUs that were dying but not yet
    dead.  This fixes some minor discrepancies and incorrect assertions
    when running generic/650.
 
 Signed-off-by: Darrick J. Wong <djwong@kernel.org>
 -----BEGIN PGP SIGNATURE-----
 
 iHUEABYKAB0WIQQ2qTKExjcn+O1o2YRKO3ySh0YRpgUCZBdAbgAKCRBKO3ySh0YR
 pkltAQCs4QO5LjYReqjUxd4cSsLtNnNon09qswRsl2GuRyI36AEAxI9QMq4Q6D9V
 ZasNbiTCkV3KPKfmp6gf1mQNLk1lGQ0=
 =Bz3q
 -----END PGP SIGNATURE-----

Merge tag 'xfs-6.3-fixes-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

Pull xfs percpu counter fixes from Darrick Wong:
 "We discovered a filesystem summary counter corruption problem that was
  traced to cpu hot-remove racing with the call to percpu_counter_sum
  that sets the free block count in the superblock when writing it to
  disk. The root cause is that percpu_counter_sum doesn't cull from
  dying cpus and hence misses those counter values if the cpu shutdown
  hooks have not yet run to merge the values.

  I'm hoping this is a fairly painless fix to the problem, since the
  dying cpu mask should generally be empty. It's been in for-next for a
  week without any complaints from the bots.

   - Fix a race in the percpu counters summation code where the
     summation failed to add in the values for any CPUs that were dying
     but not yet dead. This fixes some minor discrepancies and incorrect
     assertions when running generic/650"

* tag 'xfs-6.3-fixes-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  pcpcntr: remove percpu_counter_sum_all()
  fork: remove use of percpu_counter_sum_all
  pcpcntrs: fix dying cpu summation race
  cpumask: introduce for_each_cpu_or
2023-03-25 12:57:34 -07:00
Dave Chinner
7ba85fba47 fork: remove use of percpu_counter_sum_all
This effectively reverts the change made in commit f689054aac
("percpu_counter: add percpu_counter_sum_all interface") as the
race condition percpu_counter_sum_all() was invented to avoid is
now handled directly in percpu_counter_sum() and nobody needs to
care about summing racing with cpu unplug anymore.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2023-03-19 10:02:04 -07:00
Mike Christie
89c8e98d8c
fork: allow kernel code to call copy_process
The next patch adds helpers like create_io_thread, but for use by the
vhost layer. There are several functions, so they are in their own file
instead of cluttering up fork.c. This patch allows that new file to
call copy_process.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-03-12 10:54:43 +01:00
Mike Christie
094717586b
fork: Add kernel_clone_args flag to ignore signals
Since:

commit 10ab825bde ("change kernel threads to ignore signals instead of
blocking them")

kthreads have been ignoring signals by default, and the vhost layer has
never had a need to change that. This patch adds an option flag,
USER_WORKER_SIG_IGN, handled in copy_process() after copy_sighand()
and copy_signals() so vhost_tasks added in the next patches can continue
to ignore singals.

Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-03-12 10:54:43 +01:00
Mike Christie
11f3f500ec
fork: add kernel_clone_args flag to not dup/clone files
Each vhost device gets a thread that is used to perform IO and management
operations. Instead of a thread that is accessing a device, the thread is
part of the device, so when it creates a thread using a helper based on
copy_process we can't dup or clone the parent's files/FDS because it
would do an extra increment on ourself.

Later, when we do:

Qemu process exits:
        do_exit -> exit_files -> put_files_struct -> close_files

we would leak the device's resources because of that extra refcount
on the fd or file_struct.

This patch adds a no_files option so these worker threads can prevent
taking an extra refcount on themselves.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-03-12 10:54:43 +01:00
Mike Christie
54e6842d07
fork/vm: Move common PF_IO_WORKER behavior to new flag
This adds a new flag, PF_USER_WORKER, that's used for behavior common to
to both PF_IO_WORKER and users like vhost which will use a new helper
instead of create_io_thread because they require different behavior for
operations like signal handling.

The common behavior PF_USER_WORKER covers is the vm reclaim handling.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-03-12 10:54:43 +01:00
Mike Christie
cf587db2ee
kernel: Allow a kernel thread's name to be set in copy_process
This patch allows kernel users to pass in the thread name so it can be
set during creation instead of having to use set_task_comm after the
thread is created.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-03-12 10:52:46 +01:00
Tobias Klauser
a402f1e353
fork: allow CLONE_NEWTIME in clone3 flags
Currently, calling clone3() with CLONE_NEWTIME in clone_args->flags
fails with -EINVAL. This is because CLONE_NEWTIME intersects with
CSIGNAL. However, CSIGNAL was deprecated when clone3 was introduced in
commit 7f192e3cd3 ("fork: add clone3"), allowing re-use of that part
of clone flags.

Fix this by explicitly allowing CLONE_NEWTIME in clone3_args_valid. This
is also in line with the respective check in check_unshare_flags which
allow CLONE_NEWTIME for unshare().

Fixes: 769071ac9f ("ns: Introduce Time Namespace")
Cc: Andrey Vagin <avagin@openvz.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-03-08 12:31:34 +01:00
Linus Torvalds
3822a7c409 - Daniel Verkamp has contributed a memfd series ("mm/memfd: add
F_SEAL_EXEC") which permits the setting of the memfd execute bit at
   memfd creation time, with the option of sealing the state of the X bit.
 
 - Peter Xu adds a patch series ("mm/hugetlb: Make huge_pte_offset()
   thread-safe for pmd unshare") which addresses a rare race condition
   related to PMD unsharing.
 
 - Several folioification patch serieses from Matthew Wilcox, Vishal
   Moola, Sidhartha Kumar and Lorenzo Stoakes
 
 - Johannes Weiner has a series ("mm: push down lock_page_memcg()") which
   does perform some memcg maintenance and cleanup work.
 
 - SeongJae Park has added DAMOS filtering to DAMON, with the series
   "mm/damon/core: implement damos filter".  These filters provide users
   with finer-grained control over DAMOS's actions.  SeongJae has also done
   some DAMON cleanup work.
 
 - Kairui Song adds a series ("Clean up and fixes for swap").
 
 - Vernon Yang contributed the series "Clean up and refinement for maple
   tree".
 
 - Yu Zhao has contributed the "mm: multi-gen LRU: memcg LRU" series.  It
   adds to MGLRU an LRU of memcgs, to improve the scalability of global
   reclaim.
 
 - David Hildenbrand has added some userfaultfd cleanup work in the
   series "mm: uffd-wp + change_protection() cleanups".
 
 - Christoph Hellwig has removed the generic_writepages() library
   function in the series "remove generic_writepages".
 
 - Baolin Wang has performed some maintenance on the compaction code in
   his series "Some small improvements for compaction".
 
 - Sidhartha Kumar is doing some maintenance work on struct page in his
   series "Get rid of tail page fields".
 
 - David Hildenbrand contributed some cleanup, bugfixing and
   generalization of pte management and of pte debugging in his series "mm:
   support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on all architectures with swap
   PTEs".
 
 - Mel Gorman and Neil Brown have removed the __GFP_ATOMIC allocation
   flag in the series "Discard __GFP_ATOMIC".
 
 - Sergey Senozhatsky has improved zsmalloc's memory utilization with his
   series "zsmalloc: make zspage chain size configurable".
 
 - Joey Gouly has added prctl() support for prohibiting the creation of
   writeable+executable mappings.  The previous BPF-based approach had
   shortcomings.  See "mm: In-kernel support for memory-deny-write-execute
   (MDWE)".
 
 - Waiman Long did some kmemleak cleanup and bugfixing in the series
   "mm/kmemleak: Simplify kmemleak_cond_resched() & fix UAF".
 
 - T.J.  Alumbaugh has contributed some MGLRU cleanup work in his series
   "mm: multi-gen LRU: improve".
 
 - Jiaqi Yan has provided some enhancements to our memory error
   statistics reporting, mainly by presenting the statistics on a per-node
   basis.  See the series "Introduce per NUMA node memory error
   statistics".
 
 - Mel Gorman has a second and hopefully final shot at fixing a CPU-hog
   regression in compaction via his series "Fix excessive CPU usage during
   compaction".
 
 - Christoph Hellwig does some vmalloc maintenance work in the series
   "cleanup vfree and vunmap".
 
 - Christoph Hellwig has removed block_device_operations.rw_page() in ths
   series "remove ->rw_page".
 
 - We get some maple_tree improvements and cleanups in Liam Howlett's
   series "VMA tree type safety and remove __vma_adjust()".
 
 - Suren Baghdasaryan has done some work on the maintainability of our
   vm_flags handling in the series "introduce vm_flags modifier functions".
 
 - Some pagemap cleanup and generalization work in Mike Rapoport's series
   "mm, arch: add generic implementation of pfn_valid() for FLATMEM" and
   "fixups for generic implementation of pfn_valid()"
 
 - Baoquan He has done some work to make /proc/vmallocinfo and
   /proc/kcore better represent the real state of things in his series
   "mm/vmalloc.c: allow vread() to read out vm_map_ram areas".
 
 - Jason Gunthorpe rationalized the GUP system's interface to the rest of
   the kernel in the series "Simplify the external interface for GUP".
 
 - SeongJae Park wishes to migrate people from DAMON's debugfs interface
   over to its sysfs interface.  To support this, we'll temporarily be
   printing warnings when people use the debugfs interface.  See the series
   "mm/damon: deprecate DAMON debugfs interface".
 
 - Andrey Konovalov provided the accurately named "lib/stackdepot: fixes
   and clean-ups" series.
 
 - Huang Ying has provided a dramatic reduction in migration's TLB flush
   IPI rates with the series "migrate_pages(): batch TLB flushing".
 
 - Arnd Bergmann has some objtool fixups in "objtool warning fixes".
 -----BEGIN PGP SIGNATURE-----
 
 iHUEABYIAB0WIQTTMBEPP41GrTpTJgfdBJ7gKXxAjgUCY/PoPQAKCRDdBJ7gKXxA
 jlvpAPsFECUBBl20qSue2zCYWnHC7Yk4q9ytTkPB/MMDrFEN9wD/SNKEm2UoK6/K
 DmxHkn0LAitGgJRS/W9w81yrgig9tAQ=
 =MlGs
 -----END PGP SIGNATURE-----

Merge tag 'mm-stable-2023-02-20-13-37' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - Daniel Verkamp has contributed a memfd series ("mm/memfd: add
   F_SEAL_EXEC") which permits the setting of the memfd execute bit at
   memfd creation time, with the option of sealing the state of the X
   bit.

 - Peter Xu adds a patch series ("mm/hugetlb: Make huge_pte_offset()
   thread-safe for pmd unshare") which addresses a rare race condition
   related to PMD unsharing.

 - Several folioification patch serieses from Matthew Wilcox, Vishal
   Moola, Sidhartha Kumar and Lorenzo Stoakes

 - Johannes Weiner has a series ("mm: push down lock_page_memcg()")
   which does perform some memcg maintenance and cleanup work.

 - SeongJae Park has added DAMOS filtering to DAMON, with the series
   "mm/damon/core: implement damos filter".

   These filters provide users with finer-grained control over DAMOS's
   actions. SeongJae has also done some DAMON cleanup work.

 - Kairui Song adds a series ("Clean up and fixes for swap").

 - Vernon Yang contributed the series "Clean up and refinement for maple
   tree".

 - Yu Zhao has contributed the "mm: multi-gen LRU: memcg LRU" series. It
   adds to MGLRU an LRU of memcgs, to improve the scalability of global
   reclaim.

 - David Hildenbrand has added some userfaultfd cleanup work in the
   series "mm: uffd-wp + change_protection() cleanups".

 - Christoph Hellwig has removed the generic_writepages() library
   function in the series "remove generic_writepages".

 - Baolin Wang has performed some maintenance on the compaction code in
   his series "Some small improvements for compaction".

 - Sidhartha Kumar is doing some maintenance work on struct page in his
   series "Get rid of tail page fields".

 - David Hildenbrand contributed some cleanup, bugfixing and
   generalization of pte management and of pte debugging in his series
   "mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on all architectures with
   swap PTEs".

 - Mel Gorman and Neil Brown have removed the __GFP_ATOMIC allocation
   flag in the series "Discard __GFP_ATOMIC".

 - Sergey Senozhatsky has improved zsmalloc's memory utilization with
   his series "zsmalloc: make zspage chain size configurable".

 - Joey Gouly has added prctl() support for prohibiting the creation of
   writeable+executable mappings.

   The previous BPF-based approach had shortcomings. See "mm: In-kernel
   support for memory-deny-write-execute (MDWE)".

 - Waiman Long did some kmemleak cleanup and bugfixing in the series
   "mm/kmemleak: Simplify kmemleak_cond_resched() & fix UAF".

 - T.J. Alumbaugh has contributed some MGLRU cleanup work in his series
   "mm: multi-gen LRU: improve".

 - Jiaqi Yan has provided some enhancements to our memory error
   statistics reporting, mainly by presenting the statistics on a
   per-node basis. See the series "Introduce per NUMA node memory error
   statistics".

 - Mel Gorman has a second and hopefully final shot at fixing a CPU-hog
   regression in compaction via his series "Fix excessive CPU usage
   during compaction".

 - Christoph Hellwig does some vmalloc maintenance work in the series
   "cleanup vfree and vunmap".

 - Christoph Hellwig has removed block_device_operations.rw_page() in
   ths series "remove ->rw_page".

 - We get some maple_tree improvements and cleanups in Liam Howlett's
   series "VMA tree type safety and remove __vma_adjust()".

 - Suren Baghdasaryan has done some work on the maintainability of our
   vm_flags handling in the series "introduce vm_flags modifier
   functions".

 - Some pagemap cleanup and generalization work in Mike Rapoport's
   series "mm, arch: add generic implementation of pfn_valid() for
   FLATMEM" and "fixups for generic implementation of pfn_valid()"

 - Baoquan He has done some work to make /proc/vmallocinfo and
   /proc/kcore better represent the real state of things in his series
   "mm/vmalloc.c: allow vread() to read out vm_map_ram areas".

 - Jason Gunthorpe rationalized the GUP system's interface to the rest
   of the kernel in the series "Simplify the external interface for
   GUP".

 - SeongJae Park wishes to migrate people from DAMON's debugfs interface
   over to its sysfs interface. To support this, we'll temporarily be
   printing warnings when people use the debugfs interface. See the
   series "mm/damon: deprecate DAMON debugfs interface".

 - Andrey Konovalov provided the accurately named "lib/stackdepot: fixes
   and clean-ups" series.

 - Huang Ying has provided a dramatic reduction in migration's TLB flush
   IPI rates with the series "migrate_pages(): batch TLB flushing".

 - Arnd Bergmann has some objtool fixups in "objtool warning fixes".

* tag 'mm-stable-2023-02-20-13-37' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (505 commits)
  include/linux/migrate.h: remove unneeded externs
  mm/memory_hotplug: cleanup return value handing in do_migrate_range()
  mm/uffd: fix comment in handling pte markers
  mm: change to return bool for isolate_movable_page()
  mm: hugetlb: change to return bool for isolate_hugetlb()
  mm: change to return bool for isolate_lru_page()
  mm: change to return bool for folio_isolate_lru()
  objtool: add UACCESS exceptions for __tsan_volatile_read/write
  kmsan: disable ftrace in kmsan core code
  kasan: mark addr_has_metadata __always_inline
  mm: memcontrol: rename memcg_kmem_enabled()
  sh: initialize max_mapnr
  m68k/nommu: add missing definition of ARCH_PFN_OFFSET
  mm: percpu: fix incorrect size in pcpu_obj_full_size()
  maple_tree: reduce stack usage with gcc-9 and earlier
  mm: page_alloc: call panic() when memoryless node allocation fails
  mm: multi-gen LRU: avoid futile retries
  migrate_pages: move THP/hugetlb migration support check to simplify code
  migrate_pages: batch flushing TLB
  migrate_pages: share more code between _unmap and _move
  ...
2023-02-23 17:09:35 -08:00
Linus Torvalds
1f2d9ffc7a Scheduler updates in this cycle are:
- Improve the scalability of the CFS bandwidth unthrottling logic
    with large number of CPUs.
 
  - Fix & rework various cpuidle routines, simplify interaction with
    the generic scheduler code. Add __cpuidle methods as noinstr to
    objtool's noinstr detection and fix boatloads of cpuidle bugs & quirks.
 
  - Add new ABI: introduce MEMBARRIER_CMD_GET_REGISTRATIONS,
    to query previously issued registrations.
 
  - Limit scheduler slice duration to the sysctl_sched_latency period,
    to improve scheduling granularity with a large number of SCHED_IDLE
    tasks.
 
  - Debuggability enhancement on sys_exit(): warn about disabled IRQs,
    but also enable them to prevent a cascade of followup problems and
    repeat warnings.
 
  - Fix the rescheduling logic in prio_changed_dl().
 
  - Micro-optimize cpufreq and sched-util methods.
 
  - Micro-optimize ttwu_runnable()
 
  - Micro-optimize the idle-scanning in update_numa_stats(),
    select_idle_capacity() and steal_cookie_task().
 
  - Update the RSEQ code & self-tests
 
  - Constify various scheduler methods
 
  - Remove unused methods
 
  - Refine __init tags
 
  - Documentation updates
 
  - ... Misc other cleanups, fixes
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
 -----BEGIN PGP SIGNATURE-----
 
 iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAmPzbJwRHG1pbmdvQGtl
 cm5lbC5vcmcACgkQEnMQ0APhK1iIvA//ZcEaB8Z6ChLRQjM+bsaudKJu3pdLQbPK
 iYbP8Da+LsAfxbEfYuGV3m+jIp0LlBOtsI/EezxQrXV+V7FvNyAX9Y00eEu/zlj8
 7Jn3LMy/DBYTwH7LwVdcU0MyIVI8ZPc6WNnkx0LOtGZn8n+qfHPSDzcP3CW+a5AV
 UvllPYpYyEmsX0Eby7CF4Ue8mSmbViw/xR3rNr8ZSve0c25XzKabw8O9kE3jiHxP
 d/zERJoAYeDyYUEuZqhfn5dTlB4an4IjNEkAfRE5SQ09RA8Gkxsa5Ar8gob9e9M1
 eQsdd4/bdhnrkM8L5qDZczqmgCTZ2bukQrxkBXhRDhLgoFxwAn77b+2ZjmIW3Lae
 AyGqRcDSg1q2oxaYm5ZiuO/t26aDOZu9vPHyHRDGt95EGbZlrp+GgeePyfCigJYz
 UmPdZAAcHdSymnnnlcvdG37WVvaVkpgWZzd8LbtBi23QR+Zc4WQ2IlgnUS5WKNNf
 VOBcAcP6E1IslDotZDQCc2dPFFQoQQEssVooyUc5oMytm7BsvxXLOeHG+Ncu/8uc
 H+U8Qn8jnqTxJbC5hkWQIJlhVKCq2FJrHxxySYTKROfUNcDgCmxboFeAcXTCIU1K
 T0S+sdoTS/CvtLklRkG0j6B8N4N98mOd9cFwUV3tX+/gMLMep3hCQs5L76JagvC5
 skkQXoONNaM=
 =l1nN
 -----END PGP SIGNATURE-----

Merge tag 'sched-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:

 - Improve the scalability of the CFS bandwidth unthrottling logic with
   large number of CPUs.

 - Fix & rework various cpuidle routines, simplify interaction with the
   generic scheduler code. Add __cpuidle methods as noinstr to objtool's
   noinstr detection and fix boatloads of cpuidle bugs & quirks.

 - Add new ABI: introduce MEMBARRIER_CMD_GET_REGISTRATIONS, to query
   previously issued registrations.

 - Limit scheduler slice duration to the sysctl_sched_latency period, to
   improve scheduling granularity with a large number of SCHED_IDLE
   tasks.

 - Debuggability enhancement on sys_exit(): warn about disabled IRQs,
   but also enable them to prevent a cascade of followup problems and
   repeat warnings.

 - Fix the rescheduling logic in prio_changed_dl().

 - Micro-optimize cpufreq and sched-util methods.

 - Micro-optimize ttwu_runnable()

 - Micro-optimize the idle-scanning in update_numa_stats(),
   select_idle_capacity() and steal_cookie_task().

 - Update the RSEQ code & self-tests

 - Constify various scheduler methods

 - Remove unused methods

 - Refine __init tags

 - Documentation updates

 - Misc other cleanups, fixes

* tag 'sched-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (110 commits)
  sched/rt: pick_next_rt_entity(): check list_entry
  sched/deadline: Add more reschedule cases to prio_changed_dl()
  sched/fair: sanitize vruntime of entity being placed
  sched/fair: Remove capacity inversion detection
  sched/fair: unlink misfit task from cpu overutilized
  objtool: mem*() are not uaccess safe
  cpuidle: Fix poll_idle() noinstr annotation
  sched/clock: Make local_clock() noinstr
  sched/clock/x86: Mark sched_clock() noinstr
  x86/pvclock: Improve atomic update of last_value in pvclock_clocksource_read()
  x86/atomics: Always inline arch_atomic64*()
  cpuidle: tracing, preempt: Squash _rcuidle tracing
  cpuidle: tracing: Warn about !rcu_is_watching()
  cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUG
  cpuidle: drivers: firmware: psci: Dont instrument suspend code
  KVM: selftests: Fix build of rseq test
  exit: Detect and fix irq disabled state in oops
  cpuidle, arm64: Fix the ARM64 cpuidle logic
  cpuidle: mvebu: Fix duplicate flags assignment
  sched/fair: Limit sched slice duration
  ...
2023-02-20 17:41:08 -08:00
Suren Baghdasaryan
e430a95a04 mm: replace VM_LOCKED_CLEAR_MASK with VM_LOCKED_MASK
To simplify the usage of VM_LOCKED_CLEAR_MASK in vm_flags_clear(), replace
it with VM_LOCKED_MASK bitmask and convert all users.

Link: https://lkml.kernel.org/r/20230126193752.297968-4-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjun Roy <arjunroy@google.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Minchan Kim <minchan@google.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Oskolkov <posk@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Punit Agrawal <punit.agrawal@bytedance.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Sebastian Reichel <sebastian.reichel@collabora.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-09 16:51:39 -08:00
Suren Baghdasaryan
06e78b614e kernel/fork: convert vma assignment to a memcpy
Patch series "introduce vm_flags modifier functions", v4.

This patchset was originally published as a part of per-VMA locking [1]
and was split after suggestion that it's viable on its own and to
facilitate the review process.  It is now a preprequisite for the next
version of per-VMA lock patchset, which reuses vm_flags modifier functions
to lock the VMA when vm_flags are being updated.

VMA vm_flags modifications are usually done under exclusive mmap_lock
protection because this attrubute affects other decisions like VMA merging
or splitting and races should be prevented.  Introduce vm_flags modifier
functions to enforce correct locking.


This patch (of 7):

Convert vma assignment in vm_area_dup() to a memcpy() to prevent compiler
errors when we add a const modifier to vma->vm_flags.

Link: https://lkml.kernel.org/r/20230126193752.297968-1-surenb@google.com
Link: https://lkml.kernel.org/r/20230126193752.297968-2-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjun Roy <arjunroy@google.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: David Rientjes <rientjes@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Oskolkov <posk@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Punit Agrawal <punit.agrawal@bytedance.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-09 16:51:38 -08:00
Liam R. Howlett
3b9dbd5e91 kernel/fork: convert forking to using the vmi iterator
Avoid using the maple tree interface directly.  This gains type safety.

Link: https://lkml.kernel.org/r/20230120162650.984577-10-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-09 16:51:31 -08:00
Christoph Hellwig
f05837ed73 blk-cgroup: store a gendisk to throttle in struct task_struct
Switch from a request_queue pointer and reference to a gendisk once
for the throttle information in struct task_struct.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Link: https://lore.kernel.org/r/20230203150400.3199230-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-02-03 08:20:05 -07:00
Mathieu Desnoyers
af7f588d8f sched: Introduce per-memory-map concurrency ID
This feature allows the scheduler to expose a per-memory map concurrency
ID to user-space. This concurrency ID is within the possible cpus range,
and is temporarily (and uniquely) assigned while threads are actively
running within a memory map. If a memory map has fewer threads than
cores, or is limited to run on few cores concurrently through sched
affinity or cgroup cpusets, the concurrency IDs will be values close
to 0, thus allowing efficient use of user-space memory for per-cpu
data structures.

This feature is meant to be exposed by a new rseq thread area field.

The primary purpose of this feature is to do the heavy-lifting needed
by memory allocators to allow them to use per-cpu data structures
efficiently in the following situations:

- Single-threaded applications,
- Multi-threaded applications on large systems (many cores) with limited
  cpu affinity mask,
- Multi-threaded applications on large systems (many cores) with
  restricted cgroup cpuset per container.

One of the key concern from scheduler maintainers is the overhead
associated with additional spin locks or atomic operations in the
scheduler fast-path. This is why the following optimization is
implemented.

On context switch between threads belonging to the same memory map,
transfer the mm_cid from prev to next without any atomic ops. This
takes care of use-cases involving frequent context switch between
threads belonging to the same memory map.

Additional optimizations can be done if the spin locks added when
context switching between threads belonging to different memory maps end
up being a performance bottleneck. Those are left out of this patch
though. A performance impact would have to be clearly demonstrated to
justify the added complexity.

The credit goes to Paul Turner (Google) for the original virtual cpu id
idea. This feature is implemented based on the discussions with Paul
Turner and Peter Oskolkov (Google), but I took the liberty to implement
scheduler fast-path optimizations and my own NUMA-awareness scheme. The
rumor has it that Google have been running a rseq vcpu_id extension
internally in production for a year. The tcmalloc source code indeed has
comments hinting at a vcpu_id prototype extension to the rseq system
call [1].

The following benchmarks do not show any significant overhead added to
the scheduler context switch by this feature:

* perf bench sched messaging (process)

Baseline:                    86.5±0.3 ms
With mm_cid:                 86.7±2.6 ms

* perf bench sched messaging (threaded)

Baseline:                    84.3±3.0 ms
With mm_cid:                 84.7±2.6 ms

* hackbench (process)

Baseline:                    82.9±2.7 ms
With mm_cid:                 82.9±2.9 ms

* hackbench (threaded)

Baseline:                    85.2±2.6 ms
With mm_cid:                 84.4±2.9 ms

[1] https://github.com/google/tcmalloc/blob/master/tcmalloc/internal/linux_syscall_support.h#L26

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221122203932.231377-8-mathieu.desnoyers@efficios.com
2022-12-27 12:52:11 +01:00
Linus Torvalds
4f292c4de4 New Feature:
* Randomize the per-cpu entry areas
 Cleanups:
 * Have CR3_ADDR_MASK use PHYSICAL_PAGE_MASK instead of open
   coding it
 * Move to "native" set_memory_rox() helper
 * Clean up pmd_get_atomic() and i386-PAE
 * Remove some unused page table size macros
 -----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCgAdFiEEV76QKkVc4xCGURexaDWVMHDJkrAFAmOc53UACgkQaDWVMHDJ
 krCUHw//SGZ+La0hLZLAiAiZTXLZZHpYkOmg1Oj1+11qSU11uZzTFqDpauhaKpRS
 cJCSh+D+RXe5e2ipgt0+Zl0hESLt7pJf8258OE4ra0DL/IlyO9uqruAs9Kn3eRS/
 Fk76nG8gdEU+JKJqpG02GqOLslYQuIy96n9hpuj1x25b614+uezPfC7S4XEat0NT
 MbJQ+jnVDf16aJIJkzT+iSwhubDVeh+bSHeO0SSCzX23WLUqDeg5NvlyxoCHGbBh
 UpUTWggV/0pYAkBKRHToeJs8qTWREwuuH/8JGewpe9A0tjdB5wyZfNL2PuracweN
 9MauXC3T5f0+Ca4yIIaPq1fF7Ny/PR2dBFihk27rOD0N7tjaZxNwal2pB1sZcmvZ
 +PAokjyTPVH5ZXjkMYGGAUe1jyjwr2+TgFSZxhTnDuGtyVQiY4pihGKOifLCX6tv
 x6khvYeTBw7wfaDRtKEAf+2kLHYn+71HszHP/8bNKX9T03h+Zf0i1wdZu5xbM5Gc
 VK2wR7bCC+UftJJYG0pldcHg2qaF19RBHK2tLwp7zngUv7lTbkKfkgKjre73KV2a
 D4b76lrqdUMo6UYwYdw7WtDyarZS4OVLq2DcNhwwMddBCaX8kyN5a4AqwQlZYJ0u
 dM+kuMofE8U3yMxmMhJimkZUsj09yLHIqfynY0jbAcU3nhKZZNY=
 =wwVF
 -----END PGP SIGNATURE-----

Merge tag 'x86_mm_for_6.2_v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 mm updates from Dave Hansen:
 "New Feature:

   - Randomize the per-cpu entry areas

  Cleanups:

   - Have CR3_ADDR_MASK use PHYSICAL_PAGE_MASK instead of open coding it

   - Move to "native" set_memory_rox() helper

   - Clean up pmd_get_atomic() and i386-PAE

   - Remove some unused page table size macros"

* tag 'x86_mm_for_6.2_v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (35 commits)
  x86/mm: Ensure forced page table splitting
  x86/kasan: Populate shadow for shared chunk of the CPU entry area
  x86/kasan: Add helpers to align shadow addresses up and down
  x86/kasan: Rename local CPU_ENTRY_AREA variables to shorten names
  x86/mm: Populate KASAN shadow for entire per-CPU range of CPU entry area
  x86/mm: Recompute physical address for every page of per-CPU CEA mapping
  x86/mm: Rename __change_page_attr_set_clr(.checkalias)
  x86/mm: Inhibit _PAGE_NX changes from cpa_process_alias()
  x86/mm: Untangle __change_page_attr_set_clr(.checkalias)
  x86/mm: Add a few comments
  x86/mm: Fix CR3_ADDR_MASK
  x86/mm: Remove P*D_PAGE_MASK and P*D_PAGE_SIZE macros
  mm: Convert __HAVE_ARCH_P..P_GET to the new style
  mm: Remove pointless barrier() after pmdp_get_lockless()
  x86/mm/pae: Get rid of set_64bit()
  x86_64: Remove pointless set_64bit() usage
  x86/mm/pae: Be consistent with pXXp_get_and_clear()
  x86/mm/pae: Use WRITE_ONCE()
  x86/mm/pae: Don't (ab)use atomic64
  mm/gup: Fix the lockless PMD access
  ...
2022-12-17 14:06:53 -06:00
Peter Zijlstra
3f4c8211d9 x86/mm: Use mm_alloc() in poking_init()
Instead of duplicating init_mm, allocate a fresh mm. The advantage is
that mm_alloc() has much simpler dependencies. Additionally it makes
more conceptual sense, init_mm has no (and must not have) user state
to duplicate.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20221025201057.816175235@infradead.org
2022-12-15 10:37:26 -08:00
Peter Zijlstra
af80602799 mm: Move mm_cachep initialization to mm_init()
In order to allow using mm_alloc() much earlier, move initializing
mm_cachep into mm_init().

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20221025201057.751153381@infradead.org
2022-12-15 10:37:26 -08:00
Linus Torvalds
e2ca6ba6ba MM patches for 6.2-rc1.
- More userfaultfs work from Peter Xu.
 
 - Several convert-to-folios series from Sidhartha Kumar and Huang Ying.
 
 - Some filemap cleanups from Vishal Moola.
 
 - David Hildenbrand added the ability to selftest anon memory COW handling.
 
 - Some cpuset simplifications from Liu Shixin.
 
 - Addition of vmalloc tracing support by Uladzislau Rezki.
 
 - Some pagecache folioifications and simplifications from Matthew Wilcox.
 
 - A pagemap cleanup from Kefeng Wang: we have VM_ACCESS_FLAGS, so use it.
 
 - Miguel Ojeda contributed some cleanups for our use of the
   __no_sanitize_thread__ gcc keyword.  This series shold have been in the
   non-MM tree, my bad.
 
 - Naoya Horiguchi improved the interaction between memory poisoning and
   memory section removal for huge pages.
 
 - DAMON cleanups and tuneups from SeongJae Park
 
 - Tony Luck fixed the handling of COW faults against poisoned pages.
 
 - Peter Xu utilized the PTE marker code for handling swapin errors.
 
 - Hugh Dickins reworked compound page mapcount handling, simplifying it
   and making it more efficient.
 
 - Removal of the autonuma savedwrite infrastructure from Nadav Amit and
   David Hildenbrand.
 
 - zram support for multiple compression streams from Sergey Senozhatsky.
 
 - David Hildenbrand reworked the GUP code's R/O long-term pinning so
   that drivers no longer need to use the FOLL_FORCE workaround which
   didn't work very well anyway.
 
 - Mel Gorman altered the page allocator so that local IRQs can remnain
   enabled during per-cpu page allocations.
 
 - Vishal Moola removed the try_to_release_page() wrapper.
 
 - Stefan Roesch added some per-BDI sysfs tunables which are used to
   prevent network block devices from dirtying excessive amounts of
   pagecache.
 
 - David Hildenbrand did some cleanup and repair work on KSM COW
   breaking.
 
 - Nhat Pham and Johannes Weiner have implemented writeback in zswap's
   zsmalloc backend.
 
 - Brian Foster has fixed a longstanding corner-case oddity in
   file[map]_write_and_wait_range().
 
 - sparse-vmemmap changes for MIPS, LoongArch and NIOS2 from Feiyang
   Chen.
 
 - Shiyang Ruan has done some work on fsdax, to make its reflink mode
   work better under xfstests.  Better, but still not perfect.
 
 - Christoph Hellwig has removed the .writepage() method from several
   filesystems.  They only need .writepages().
 
 - Yosry Ahmed wrote a series which fixes the memcg reclaim target
   beancounting.
 
 - David Hildenbrand has fixed some of our MM selftests for 32-bit
   machines.
 
 - Many singleton patches, as usual.
 -----BEGIN PGP SIGNATURE-----
 
 iHUEABYKAB0WIQTTMBEPP41GrTpTJgfdBJ7gKXxAjgUCY5j6ZwAKCRDdBJ7gKXxA
 jkDYAP9qNeVqp9iuHjZNTqzMXkfmJPsw2kmy2P+VdzYVuQRcJgEAgoV9d7oMq4ml
 CodAgiA51qwzId3GRytIo/tfWZSezgA=
 =d19R
 -----END PGP SIGNATURE-----

Merge tag 'mm-stable-2022-12-13' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - More userfaultfs work from Peter Xu

 - Several convert-to-folios series from Sidhartha Kumar and Huang Ying

 - Some filemap cleanups from Vishal Moola

 - David Hildenbrand added the ability to selftest anon memory COW
   handling

 - Some cpuset simplifications from Liu Shixin

 - Addition of vmalloc tracing support by Uladzislau Rezki

 - Some pagecache folioifications and simplifications from Matthew
   Wilcox

 - A pagemap cleanup from Kefeng Wang: we have VM_ACCESS_FLAGS, so use
   it

 - Miguel Ojeda contributed some cleanups for our use of the
   __no_sanitize_thread__ gcc keyword.

   This series should have been in the non-MM tree, my bad

 - Naoya Horiguchi improved the interaction between memory poisoning and
   memory section removal for huge pages

 - DAMON cleanups and tuneups from SeongJae Park

 - Tony Luck fixed the handling of COW faults against poisoned pages

 - Peter Xu utilized the PTE marker code for handling swapin errors

 - Hugh Dickins reworked compound page mapcount handling, simplifying it
   and making it more efficient

 - Removal of the autonuma savedwrite infrastructure from Nadav Amit and
   David Hildenbrand

 - zram support for multiple compression streams from Sergey Senozhatsky

 - David Hildenbrand reworked the GUP code's R/O long-term pinning so
   that drivers no longer need to use the FOLL_FORCE workaround which
   didn't work very well anyway

 - Mel Gorman altered the page allocator so that local IRQs can remnain
   enabled during per-cpu page allocations

 - Vishal Moola removed the try_to_release_page() wrapper

 - Stefan Roesch added some per-BDI sysfs tunables which are used to
   prevent network block devices from dirtying excessive amounts of
   pagecache

 - David Hildenbrand did some cleanup and repair work on KSM COW
   breaking

 - Nhat Pham and Johannes Weiner have implemented writeback in zswap's
   zsmalloc backend

 - Brian Foster has fixed a longstanding corner-case oddity in
   file[map]_write_and_wait_range()

 - sparse-vmemmap changes for MIPS, LoongArch and NIOS2 from Feiyang
   Chen

 - Shiyang Ruan has done some work on fsdax, to make its reflink mode
   work better under xfstests. Better, but still not perfect

 - Christoph Hellwig has removed the .writepage() method from several
   filesystems. They only need .writepages()

 - Yosry Ahmed wrote a series which fixes the memcg reclaim target
   beancounting

 - David Hildenbrand has fixed some of our MM selftests for 32-bit
   machines

 - Many singleton patches, as usual

* tag 'mm-stable-2022-12-13' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (313 commits)
  mm/hugetlb: set head flag before setting compound_order in __prep_compound_gigantic_folio
  mm: mmu_gather: allow more than one batch of delayed rmaps
  mm: fix typo in struct pglist_data code comment
  kmsan: fix memcpy tests
  mm: add cond_resched() in swapin_walk_pmd_entry()
  mm: do not show fs mm pc for VM_LOCKONFAULT pages
  selftests/vm: ksm_functional_tests: fixes for 32bit
  selftests/vm: cow: fix compile warning on 32bit
  selftests/vm: madv_populate: fix missing MADV_POPULATE_(READ|WRITE) definitions
  mm/gup_test: fix PIN_LONGTERM_TEST_READ with highmem
  mm,thp,rmap: fix races between updates of subpages_mapcount
  mm: memcg: fix swapcached stat accounting
  mm: add nodes= arg to memory.reclaim
  mm: disable top-tier fallback to reclaim on proactive reclaim
  selftests: cgroup: make sure reclaim target memcg is unprotected
  selftests: cgroup: refactor proactive reclaim code to reclaim_until()
  mm: memcg: fix stale protection of reclaim target memcg
  mm/mmap: properly unaccount memory on mas_preallocate() failure
  omfs: remove ->writepage
  jfs: remove ->writepage
  ...
2022-12-13 19:29:45 -08:00
Linus Torvalds
268325bda5 Random number generator updates for Linux 6.2-rc1.
-----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCAAdFiEEq5lC5tSkz8NBJiCnSfxwEqXeA64FAmOU+U8ACgkQSfxwEqXe
 A67NnQ//Y5DltmvibyPd7r1TFT2gUYv+Rx3sUV9ZE1NYptd/SWhhcL8c5FZ70Fuw
 bSKCa1uiWjOxosjXT1kGrWq3de7q7oUpAPSOGxgxzoaNURIt58N/ajItCX/4Au8I
 RlGAScHy5e5t41/26a498kB6qJ441fBEqCYKQpPLINMBAhe8TQ+NVp0rlpUwNHFX
 WrUGg4oKWxdBIW3HkDirQjJWDkkAiklRTifQh/Al4b6QDbOnRUGGCeckNOhixsvS
 waHWTld+Td8jRrA4b82tUb2uVZ2/b8dEvj/A8CuTv4yC0lywoyMgBWmJAGOC+UmT
 ZVNdGW02Jc2T+Iap8ZdsEmeLHNqbli4+IcbY5xNlov+tHJ2oz41H9TZoYKbudlr6
 /ReAUPSn7i50PhbQlEruj3eg+M2gjOeh8OF8UKwwRK8PghvyWQ1ScW0l3kUhPIhI
 PdIG6j4+D2mJc1FIj2rTVB+Bg933x6S+qx4zDxGlNp62AARUFYf6EgyD6aXFQVuX
 RxcKb6cjRuFkzFiKc8zkqg5edZH+IJcPNuIBmABqTGBOxbZWURXzIQvK/iULqZa4
 CdGAFIs6FuOh8pFHLI3R4YoHBopbHup/xKDEeAO9KZGyeVIuOSERDxxo5f/ITzcq
 APvT77DFOEuyvanr8RMqqh0yUjzcddXqw9+ieufsAyDwjD9DTuE=
 =QRhK
 -----END PGP SIGNATURE-----

Merge tag 'random-6.2-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random

Pull random number generator updates from Jason Donenfeld:

 - Replace prandom_u32_max() and various open-coded variants of it,
   there is now a new family of functions that uses fast rejection
   sampling to choose properly uniformly random numbers within an
   interval:

       get_random_u32_below(ceil) - [0, ceil)
       get_random_u32_above(floor) - (floor, U32_MAX]
       get_random_u32_inclusive(floor, ceil) - [floor, ceil]

   Coccinelle was used to convert all current users of
   prandom_u32_max(), as well as many open-coded patterns, resulting in
   improvements throughout the tree.

   I'll have a "late" 6.1-rc1 pull for you that removes the now unused
   prandom_u32_max() function, just in case any other trees add a new
   use case of it that needs to converted. According to linux-next,
   there may be two trivial cases of prandom_u32_max() reintroductions
   that are fixable with a 's/.../.../'. So I'll have for you a final
   conversion patch doing that alongside the removal patch during the
   second week.

   This is a treewide change that touches many files throughout.

 - More consistent use of get_random_canary().

 - Updates to comments, documentation, tests, headers, and
   simplification in configuration.

 - The arch_get_random*_early() abstraction was only used by arm64 and
   wasn't entirely useful, so this has been replaced by code that works
   in all relevant contexts.

 - The kernel will use and manage random seeds in non-volatile EFI
   variables, refreshing a variable with a fresh seed when the RNG is
   initialized. The RNG GUID namespace is then hidden from efivarfs to
   prevent accidental leakage.

   These changes are split into random.c infrastructure code used in the
   EFI subsystem, in this pull request, and related support inside of
   EFISTUB, in Ard's EFI tree. These are co-dependent for full
   functionality, but the order of merging doesn't matter.

 - Part of the infrastructure added for the EFI support is also used for
   an improvement to the way vsprintf initializes its siphash key,
   replacing an sleep loop wart.

 - The hardware RNG framework now always calls its correct random.c
   input function, add_hwgenerator_randomness(), rather than sometimes
   going through helpers better suited for other cases.

 - The add_latent_entropy() function has long been called from the fork
   handler, but is a no-op when the latent entropy gcc plugin isn't
   used, which is fine for the purposes of latent entropy.

   But it was missing out on the cycle counter that was also being mixed
   in beside the latent entropy variable. So now, if the latent entropy
   gcc plugin isn't enabled, add_latent_entropy() will expand to a call
   to add_device_randomness(NULL, 0), which adds a cycle counter,
   without the absent latent entropy variable.

 - The RNG is now reseeded from a delayed worker, rather than on demand
   when used. Always running from a worker allows it to make use of the
   CPU RNG on platforms like S390x, whose instructions are too slow to
   do so from interrupts. It also has the effect of adding in new inputs
   more frequently with more regularity, amounting to a long term
   transcript of random values. Plus, it helps a bit with the upcoming
   vDSO implementation (which isn't yet ready for 6.2).

 - The jitter entropy algorithm now tries to execute on many different
   CPUs, round-robining, in hopes of hitting even more memory latencies
   and other unpredictable effects. It also will mix in a cycle counter
   when the entropy timer fires, in addition to being mixed in from the
   main loop, to account more explicitly for fluctuations in that timer
   firing. And the state it touches is now kept within the same cache
   line, so that it's assured that the different execution contexts will
   cause latencies.

* tag 'random-6.2-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random: (23 commits)
  random: include <linux/once.h> in the right header
  random: align entropy_timer_state to cache line
  random: mix in cycle counter when jitter timer fires
  random: spread out jitter callback to different CPUs
  random: remove extraneous period and add a missing one in comments
  efi: random: refresh non-volatile random seed when RNG is initialized
  vsprintf: initialize siphash key using notifier
  random: add back async readiness notifier
  random: reseed in delayed work rather than on-demand
  random: always mix cycle counter in add_latent_entropy()
  hw_random: use add_hwgenerator_randomness() for early entropy
  random: modernize documentation comment on get_random_bytes()
  random: adjust comment to account for removed function
  random: remove early archrandom abstraction
  random: use random.trust_{bootloader,cpu} command line option only
  stackprotector: actually use get_random_canary()
  stackprotector: move get_random_canary() into stackprotector.h
  treewide: use get_random_u32_inclusive() when possible
  treewide: use get_random_u32_{above,below}() instead of manual loop
  treewide: use get_random_u32_below() instead of deprecated function
  ...
2022-12-12 16:22:22 -08:00
Linus Torvalds
7fc035058e execve updates for v6.2-rc1
- Add timens support (when switching mm). This version has survived
   in -next for the entire cycle (Andrei Vagin).
 
 - Various small bug fixes, refactoring, and readability improvements
   (Bernd Edlinger, Rolf Eike Beer, Bo Liu, Li Zetao Liu Shixin).
 
 - Remove FOLL_FORCE for stack setup (Kees Cook).
 
 - Whilespace cleanups (Rolf Eike Beer, Kees Cook).
 -----BEGIN PGP SIGNATURE-----
 
 iQJKBAABCgA0FiEEpcP2jyKd1g9yPm4TiXL039xtwCYFAmOOjsgWHGtlZXNjb29r
 QGNocm9taXVtLm9yZwAKCRCJcvTf3G3AJqwED/9mjtKL2GwHOYKsfhtc0m4HVGBw
 gxTEKuyo5mRwaRLg2bfuWe1OQfeGWQd9+IZ83Kr2ijzm4R16Gslv9i69Iwdf2tce
 iFf2R+iR7On+zNokHxaNflRH9fMsZLobVFqzLvB73BUF82ybJlTR3WMnQhS6HZQB
 Gse8jRfueOnVgKldRLlgdxIucPVsXYSoBS4B0nvIUuQn3aNzDNuuctMe/5NFK0ud
 +TWMXtKzS3B9pcLTXy3e0bPk/Ptio18CBUEI+iLMAHswtNCoxx1ZCcuvnEcrd5Qr
 h2WGaRvYJ7oSUXeEsqPKuDdhqEJQH2AQoX8FzvD+hyIutQJCJzVYlHvwGCqn/Km6
 0Dalng9Pjb6z2LEie/N42LDXEQmLZO2WtJ4otpORJlsJ7ZkrLjB4u+hDU1JA/Q14
 YPWvth3fMA5vAFKvGCtpEc7YdHmghmXCW+YGXOBm625fPYnwFSXOarHfow1RKNE5
 MOM4l60WwzLIHgmr8AFUaLf8TbutXN+BKvbMRh2ToWzDYXEoywxAedHDyo4LVwEy
 mZEca/3izT1ynBcyZg1t8shf4htgLjcPHqM0B+Hq0iNMIrwtecqAcYL/Oj6XssPx
 OuQYv341KF9fV/hMy84GM2HMr0ygUmrP7b9x+PEvCwzWf/2Glaw6Z4rtCdYC+TjW
 8ZWqPqEY+LRsZsL18Q==
 =ZDYk
 -----END PGP SIGNATURE-----

Merge tag 'execve-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull execve updates from Kees Cook:
 "Most are small refactorings and bug fixes, but three things stand out:
  switching timens (which got reverted before) looks solid now,
  FOLL_FORCE has been removed (no failures seen yet across several weeks
  in -next), and some whitespace cleanups (which are long overdue).

   - Add timens support (when switching mm). This version has survived
     in -next for the entire cycle (Andrei Vagin)

   - Various small bug fixes, refactoring, and readability improvements
     (Bernd Edlinger, Rolf Eike Beer, Bo Liu, Li Zetao Liu Shixin)

   - Remove FOLL_FORCE for stack setup (Kees Cook)

   - Whitespace cleanups (Rolf Eike Beer, Kees Cook)"

* tag 'execve-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  binfmt_misc: fix shift-out-of-bounds in check_special_flags
  binfmt: Fix error return code in load_elf_fdpic_binary()
  exec: Remove FOLL_FORCE for stack setup
  binfmt_elf: replace IS_ERR() with IS_ERR_VALUE()
  binfmt_elf: simplify error handling in load_elf_phdrs()
  binfmt_elf: fix documented return value for load_elf_phdrs()
  exec: simplify initial stack size expansion
  binfmt: Fix whitespace issues
  exec: Add comments on check_unsafe_exec() fs counting
  ELF uapi: add spaces before '{'
  selftests/timens: add a test for vfork+exit
  fs/exec: switch timens when a task gets a new mm
2022-12-12 08:42:29 -08:00
Kuniyuki Iwashima
a1140cb215 seccomp: Move copy_seccomp() to no failure path.
Our syzbot instance reported memory leaks in do_seccomp() [0], similar
to the report [1].  It shows that we miss freeing struct seccomp_filter
and some objects included in it.

We can reproduce the issue with the program below [2] which calls one
seccomp() and two clone() syscalls.

The first clone()d child exits earlier than its parent and sends a
signal to kill it during the second clone(), more precisely before the
fatal_signal_pending() test in copy_process().  When the parent receives
the signal, it has to destroy the embryonic process and return -EINTR to
user space.  In the failure path, we have to call seccomp_filter_release()
to decrement the filter's refcount.

Initially, we called it in free_task() called from the failure path, but
the commit 3a15fb6ed9 ("seccomp: release filter after task is fully
dead") moved it to release_task() to notify user space as early as possible
that the filter is no longer used.

To keep the change and current seccomp refcount semantics, let's move
copy_seccomp() just after the signal check and add a WARN_ON_ONCE() in
free_task() for future debugging.

[0]:
unreferenced object 0xffff8880063add00 (size 256):
  comm "repro_seccomp", pid 230, jiffies 4294687090 (age 9.914s)
  hex dump (first 32 bytes):
    01 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00  ................
    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
  backtrace:
    do_seccomp (./include/linux/slab.h:600 ./include/linux/slab.h:733 kernel/seccomp.c:666 kernel/seccomp.c:708 kernel/seccomp.c:1871 kernel/seccomp.c:1991)
    do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
    entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)
unreferenced object 0xffffc90000035000 (size 4096):
  comm "repro_seccomp", pid 230, jiffies 4294687090 (age 9.915s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 05 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    __vmalloc_node_range (mm/vmalloc.c:3226)
    __vmalloc_node (mm/vmalloc.c:3261 (discriminator 4))
    bpf_prog_alloc_no_stats (kernel/bpf/core.c:91)
    bpf_prog_alloc (kernel/bpf/core.c:129)
    bpf_prog_create_from_user (net/core/filter.c:1414)
    do_seccomp (kernel/seccomp.c:671 kernel/seccomp.c:708 kernel/seccomp.c:1871 kernel/seccomp.c:1991)
    do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
    entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)
unreferenced object 0xffff888003fa1000 (size 1024):
  comm "repro_seccomp", pid 230, jiffies 4294687090 (age 9.915s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    bpf_prog_alloc_no_stats (./include/linux/slab.h:600 ./include/linux/slab.h:733 kernel/bpf/core.c:95)
    bpf_prog_alloc (kernel/bpf/core.c:129)
    bpf_prog_create_from_user (net/core/filter.c:1414)
    do_seccomp (kernel/seccomp.c:671 kernel/seccomp.c:708 kernel/seccomp.c:1871 kernel/seccomp.c:1991)
    do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
    entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)
unreferenced object 0xffff888006360240 (size 16):
  comm "repro_seccomp", pid 230, jiffies 4294687090 (age 9.915s)
  hex dump (first 16 bytes):
    01 00 37 00 76 65 72 6c e0 83 01 06 80 88 ff ff  ..7.verl........
  backtrace:
    bpf_prog_store_orig_filter (net/core/filter.c:1137)
    bpf_prog_create_from_user (net/core/filter.c:1428)
    do_seccomp (kernel/seccomp.c:671 kernel/seccomp.c:708 kernel/seccomp.c:1871 kernel/seccomp.c:1991)
    do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
    entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)
unreferenced object 0xffff8880060183e0 (size 8):
  comm "repro_seccomp", pid 230, jiffies 4294687090 (age 9.915s)
  hex dump (first 8 bytes):
    06 00 00 00 00 00 ff 7f                          ........
  backtrace:
    kmemdup (mm/util.c:129)
    bpf_prog_store_orig_filter (net/core/filter.c:1144)
    bpf_prog_create_from_user (net/core/filter.c:1428)
    do_seccomp (kernel/seccomp.c:671 kernel/seccomp.c:708 kernel/seccomp.c:1871 kernel/seccomp.c:1991)
    do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
    entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)

[1]: https://syzkaller.appspot.com/bug?id=2809bb0ac77ad9aa3f4afe42d6a610aba594a987

[2]:
#define _GNU_SOURCE
#include <sched.h>
#include <signal.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <linux/filter.h>
#include <linux/seccomp.h>

void main(void)
{
	struct sock_filter filter[] = {
		BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ALLOW),
	};
	struct sock_fprog fprog = {
		.len = sizeof(filter) / sizeof(filter[0]),
		.filter = filter,
	};
	long i, pid;

	syscall(__NR_seccomp, SECCOMP_SET_MODE_FILTER, 0, &fprog);

	for (i = 0; i < 2; i++) {
		pid = syscall(__NR_clone, CLONE_NEWNET | SIGKILL, NULL, NULL, 0);
		if (pid == 0)
			return;
	}
}

Fixes: 3a15fb6ed9 ("seccomp: release filter after task is fully dead")
Reported-by: syzbot+ab17848fe269b573eb71@syzkaller.appspotmail.com
Reported-by: Ayushman Dutta <ayudutta@amazon.com>
Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220823154532.82913-1-kuniyu@amazon.com
2022-12-02 11:32:53 -08:00
Shakeel Butt
f689054aac percpu_counter: add percpu_counter_sum_all interface
The percpu_counter is used for scenarios where performance is more
important than the accuracy.  For percpu_counter users, who want more
accurate information in their slowpath, percpu_counter_sum is provided
which traverses all the online CPUs to accumulate the data.  The reason it
only needs to traverse online CPUs is because percpu_counter does
implement CPU offline callback which syncs the local data of the offlined
CPU.

However there is a small race window between the online CPUs traversal of
percpu_counter_sum and the CPU offline callback.  The offline callback has
to traverse all the percpu_counters on the system to flush the CPU local
data which can be a lot.  During that time, the CPU which is going offline
has already been published as offline to all the readers.  So, as the
offline callback is running, percpu_counter_sum can be called for one
counter which has some state on the CPU going offline.  Since
percpu_counter_sum only traverses online CPUs, it will skip that specific
CPU and the offline callback might not have flushed the state for that
specific percpu_counter on that offlined CPU.

Normally this is not an issue because percpu_counter users can deal with
some inaccuracy for small time window.  However a new user i.e.  mm_struct
on the cleanup path wants to check the exact state of the percpu_counter
through check_mm().  For such users, this patch introduces
percpu_counter_sum_all() which traverses all possible CPUs and it is used
in fork.c:check_mm() to avoid the potential race.

This issue is exposed by the later patch "mm: convert mm's rss stats into
percpu_counter".

Link: https://lkml.kernel.org/r/20221109012011.881058-1-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-11-30 15:58:40 -08:00
Shakeel Butt
f1a7941243 mm: convert mm's rss stats into percpu_counter
Currently mm_struct maintains rss_stats which are updated on page fault
and the unmapping codepaths.  For page fault codepath the updates are
cached per thread with the batch of TASK_RSS_EVENTS_THRESH which is 64. 
The reason for caching is performance for multithreaded applications
otherwise the rss_stats updates may become hotspot for such applications.

However this optimization comes with the cost of error margin in the rss
stats.  The rss_stats for applications with large number of threads can be
very skewed.  At worst the error margin is (nr_threads * 64) and we have a
lot of applications with 100s of threads, so the error margin can be very
high.  Internally we had to reduce TASK_RSS_EVENTS_THRESH to 32.

Recently we started seeing the unbounded errors for rss_stats for specific
applications which use TCP rx0cp.  It seems like vm_insert_pages()
codepath does not sync rss_stats at all.

This patch converts the rss_stats into percpu_counter to convert the error
margin from (nr_threads * 64) to approximately (nr_cpus ^ 2).  However
this conversion enable us to get the accurate stats for situations where
accuracy is more important than the cpu cost.

This patch does not make such tradeoffs - we can just use
percpu_counter_add_local() for the updates and percpu_counter_sum() (or
percpu_counter_sync() + percpu_counter_read) for the readers.  At the
moment the readers are either procfs interface, oom_killer and memory
reclaim which I think are not performance critical and should be ok with
slow read.  However I think we can make that change in a separate patch.

Link: https://lkml.kernel.org/r/20221024052841.3291983-1-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-11-30 15:58:40 -08:00