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1225 commits

Author SHA1 Message Date
Andrea Arcangeli
ac5be6b47e userfaultfd: revert "userfaultfd: waitqueue: add nr wake parameter to __wake_up_locked_key"
This reverts commit 51360155ec and adapts
fs/userfaultfd.c to use the old version of that function.

It didn't look robust to call __wake_up_common with "nr == 1" when we
absolutely require wakeall semantics, but we've full control of what we
insert in the two waitqueue heads of the blocked userfaults.  No
exclusive waitqueue risks to be inserted into those two waitqueue heads
so we can as well stick to "nr == 1" of the old code and we can rely
purely on the fact no waitqueue inserted in one of the two waitqueue
heads we must enforce as wakeall, has wait->flags WQ_FLAG_EXCLUSIVE set.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Thierry Reding <treding@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-22 15:09:53 -07:00
Linus Torvalds
3ae839454e Mostly stable material, a lot of ARM fixes.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull KVM fixes from Paolo Bonzini:
 "Mostly stable material, a lot of ARM fixes"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (22 commits)
  sched: access local runqueue directly in single_task_running
  arm/arm64: KVM: Remove 'config KVM_ARM_MAX_VCPUS'
  arm64: KVM: Remove all traces of the ThumbEE registers
  arm: KVM: Disable virtual timer even if the guest is not using it
  arm64: KVM: Disable virtual timer even if the guest is not using it
  arm/arm64: KVM: vgic: Check for !irqchip_in_kernel() when mapping resources
  KVM: s390: Replace incorrect atomic_or with atomic_andnot
  arm: KVM: Fix incorrect device to IPA mapping
  arm64: KVM: Fix user access for debug registers
  KVM: vmx: fix VPID is 0000H in non-root operation
  KVM: add halt_attempted_poll to VCPU stats
  kvm: fix zero length mmio searching
  kvm: fix double free for fast mmio eventfd
  kvm: factor out core eventfd assign/deassign logic
  kvm: don't try to register to KVM_FAST_MMIO_BUS for non mmio eventfd
  KVM: make the declaration of functions within 80 characters
  KVM: arm64: add workaround for Cortex-A57 erratum #852523
  KVM: fix polling for guest halt continued even if disable it
  arm/arm64: KVM: Fix PSCI affinity info return value for non valid cores
  arm64: KVM: set {v,}TCR_EL2 RES1 bits
  ...
2015-09-18 09:23:08 -07:00
Dominik Dingel
00cc163381 sched: access local runqueue directly in single_task_running
Commit 2ee507c472 ("sched: Add function single_task_running to let a task
check if it is the only task running on a cpu") referenced the current
runqueue with the smp_processor_id.  When CONFIG_DEBUG_PREEMPT is enabled,
that is only allowed if preemption is disabled or the currrent task is
bound to the local cpu (e.g. kernel worker).

With commit f781951299 ("kvm: add halt_poll_ns module parameter") KVM
calls single_task_running. If CONFIG_DEBUG_PREEMPT is enabled that
generates a lot of kernel messages.

To avoid adding preemption in that cases, as it would limit the usefulness,
we change single_task_running to access directly the cpu local runqueue.

Cc: Tim Chen <tim.c.chen@linux.intel.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Fixes: 2ee507c472
Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-09-18 13:47:59 +02:00
Linus Torvalds
c2ea72fd86 Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
 "A migrate_tasks() locking fix, and a late-coming nohz change plus a
  nohz debug check"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: 'Annotate' migrate_tasks()
  nohz: Assert existing housekeepers when nohz full enabled
  nohz: Affine unpinned timers to housekeepers
2015-09-17 10:49:42 -07:00
Wanpeng Li
5473e0cc37 sched: 'Annotate' migrate_tasks()
Kernel testing triggered this warning:

| WARNING: CPU: 0 PID: 13 at kernel/sched/core.c:1156 do_set_cpus_allowed+0x7e/0x80()
| Modules linked in:
| CPU: 0 PID: 13 Comm: migration/0 Not tainted 4.2.0-rc1-00049-g25834c7 #2
| Call Trace:
|   dump_stack+0x4b/0x75
|   warn_slowpath_common+0x8b/0xc0
|   warn_slowpath_null+0x22/0x30
|   do_set_cpus_allowed+0x7e/0x80
|   cpuset_cpus_allowed_fallback+0x7c/0x170
|   select_fallback_rq+0x221/0x280
|   migration_call+0xe3/0x250
|   notifier_call_chain+0x53/0x70
|   __raw_notifier_call_chain+0x1e/0x30
|   cpu_notify+0x28/0x50
|   take_cpu_down+0x22/0x40
|   multi_cpu_stop+0xd5/0x140
|   cpu_stopper_thread+0xbc/0x170
|   smpboot_thread_fn+0x174/0x2f0
|   kthread+0xc4/0xe0
|   ret_from_kernel_thread+0x21/0x30

As Peterz pointed out:

| So the normal rules for changing task_struct::cpus_allowed are holding
| both pi_lock and rq->lock, such that holding either stabilizes the mask.
|
| This is so that wakeup can happen without rq->lock and load-balance
| without pi_lock.
|
| From this we already get the relaxation that we can omit acquiring
| rq->lock if the task is not on the rq, because in that case
| load-balancing will not apply to it.
|
| ** these are the rules currently tested in do_set_cpus_allowed() **
|
| Now, since __set_cpus_allowed_ptr() uses task_rq_lock() which
| unconditionally acquires both locks, we could get away with holding just
| rq->lock when on_rq for modification because that'd still exclude
| __set_cpus_allowed_ptr(), it would also work against
| __kthread_bind_mask() because that assumes !on_rq.
|
| That said, this is all somewhat fragile.
|
| Now, I don't think dropping rq->lock is quite as disastrous as it
| usually is because !cpu_active at this point, which means load-balance
| will not interfere, but that too is somewhat fragile.
|
| So we end up with a choice of two fragile..

This patch fixes it by following the rules for changing
task_struct::cpus_allowed with both pi_lock and rq->lock held.

Reported-by: kernel test robot <ying.huang@intel.com>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
[ Modified changelog and patch. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/BLU436-SMTP1660820490DE202E3934ED3806E0@phx.gbl
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-09-11 07:57:50 +02:00
Andrea Arcangeli
51360155ec userfaultfd: waitqueue: add nr wake parameter to __wake_up_locked_key
userfaultfd needs to wake all waitqueues (pass 0 as nr parameter), instead
of the current hardcoded 1 (that would wake just the first waitqueue in
the head list).

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Sanidhya Kashyap <sanidhya.gatech@gmail.com>
Cc: zhang.zhanghailiang@huawei.com
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Huangpeng (Peter)" <peter.huangpeng@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Linus Torvalds
ca520cab25 Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking and atomic updates from Ingo Molnar:
 "Main changes in this cycle are:

   - Extend atomic primitives with coherent logic op primitives
     (atomic_{or,and,xor}()) and deprecate the old partial APIs
     (atomic_{set,clear}_mask())

     The old ops were incoherent with incompatible signatures across
     architectures and with incomplete support.  Now every architecture
     supports the primitives consistently (by Peter Zijlstra)

   - Generic support for 'relaxed atomics':

       - _acquire/release/relaxed() flavours of xchg(), cmpxchg() and {add,sub}_return()
       - atomic_read_acquire()
       - atomic_set_release()

     This came out of porting qwrlock code to arm64 (by Will Deacon)

   - Clean up the fragile static_key APIs that were causing repeat bugs,
     by introducing a new one:

       DEFINE_STATIC_KEY_TRUE(name);
       DEFINE_STATIC_KEY_FALSE(name);

     which define a key of different types with an initial true/false
     value.

     Then allow:

       static_branch_likely()
       static_branch_unlikely()

     to take a key of either type and emit the right instruction for the
     case.  To be able to know the 'type' of the static key we encode it
     in the jump entry (by Peter Zijlstra)

   - Static key self-tests (by Jason Baron)

   - qrwlock optimizations (by Waiman Long)

   - small futex enhancements (by Davidlohr Bueso)

   - ... and misc other changes"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (63 commits)
  jump_label/x86: Work around asm build bug on older/backported GCCs
  locking, ARM, atomics: Define our SMP atomics in terms of _relaxed() operations
  locking, include/llist: Use linux/atomic.h instead of asm/cmpxchg.h
  locking/qrwlock: Make use of _{acquire|release|relaxed}() atomics
  locking/qrwlock: Implement queue_write_unlock() using smp_store_release()
  locking/lockref: Remove homebrew cmpxchg64_relaxed() macro definition
  locking, asm-generic: Add _{relaxed|acquire|release}() variants for 'atomic_long_t'
  locking, asm-generic: Rework atomic-long.h to avoid bulk code duplication
  locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations
  locking, compiler.h: Cast away attributes in the WRITE_ONCE() magic
  locking/static_keys: Make verify_keys() static
  jump label, locking/static_keys: Update docs
  locking/static_keys: Provide a selftest
  jump_label: Provide a self-test
  s390/uaccess, locking/static_keys: employ static_branch_likely()
  x86, tsc, locking/static_keys: Employ static_branch_likely()
  locking/static_keys: Add selftest
  locking/static_keys: Add a new static_key interface
  locking/static_keys: Rework update logic
  locking/static_keys: Add static_key_{en,dis}able() helpers
  ...
2015-09-03 15:46:07 -07:00
Linus Torvalds
8bdc69b764 Merge branch 'for-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:

 - a new PIDs controller is added.  It turns out that PIDs are actually
   an independent resource from kmem due to the limited PID space.

 - more core preparations for the v2 interface.  Once cpu side interface
   is settled, it should be ready for lifting the devel mask.
   for-4.3-unified-base was temporarily branched so that other trees
   (block) can pull cgroup core changes that blkcg changes depend on.

 - a non-critical idr_preload usage bug fix.

* 'for-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: pids: fix invalid get/put usage
  cgroup: introduce cgroup_subsys->legacy_name
  cgroup: don't print subsystems for the default hierarchy
  cgroup: make cftype->private a unsigned long
  cgroup: export cgrp_dfl_root
  cgroup: define controller file conventions
  cgroup: fix idr_preload usage
  cgroup: add documentation for the PIDs controller
  cgroup: implement the PIDs subsystem
  cgroup: allow a cgroup subsystem to reject a fork
2015-09-02 08:04:23 -07:00
Vatika Harlalka
9642d18eee nohz: Affine unpinned timers to housekeepers
The problem addressed in this patch is about affining unpinned
timers. Adaptive or Full Dynticks CPUs are currently disturbed
by unnecessary jitter due to firing of such timers on them.

This patch will affine timers to online CPUs which are not full
dynticks in NOHZ_FULL configured systems. It should not
introduce overhead in nohz full off case due to static keys.

Signed-off-by: Vatika Harlalka <vatikaharlalka@gmail.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1441119060-2230-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-09-02 10:33:22 +02:00
Linus Torvalds
65a99597f0 Merge branch 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull NOHZ updates from Ingo Molnar:
 "The main changes, mostly written by Frederic Weisbecker, include:

   - Fix some jiffies based cputime assumptions.  (No real harm because
     the concerned code isn't used by full dynticks.)

   - Simplify jiffies <-> usecs conversions.  Remove dead code.

   - Remove early hacks on nohz full code that avoided messing up idle
     nohz internals.  Now nohz integrates well full and idle and such
     hack have become needless.

   - Restart nohz full tick from irq exit.  (A simplification and a
     preparation for future optimization on scheduler kick to nohz
     full)

   - Code cleanups.

   - Tile driver isolation enhancement on top of nohz.  (Chris Metcalf)"

* 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  nohz: Remove useless argument on tick_nohz_task_switch()
  nohz: Move tick_nohz_restart_sched_tick() above its users
  nohz: Restart nohz full tick from irq exit
  nohz: Remove idle task special case
  nohz: Prevent tilegx network driver interrupts
  alpha: Fix jiffies based cputime assumption
  apm32: Fix cputime == jiffies assumption
  jiffies: Remove HZ > USEC_PER_SEC special case
2015-08-31 21:04:24 -07:00
Linus Torvalds
418c2e1f67 Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fix from Ingo Molnar:
 "This is a leftover scheduler fix from the v4.2 cycle"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Fix cpu_active_mask/cpu_online_mask race
2015-08-31 20:55:23 -07:00
Linus Torvalds
a1d8561172 Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
 "The biggest change in this cycle is the rewrite of the main SMP load
  balancing metric: the CPU load/utilization.  The main goal was to make
  the metric more precise and more representative - see the changelog of
  this commit for the gory details:

    9d89c257df ("sched/fair: Rewrite runnable load and utilization average tracking")

  It is done in a way that significantly reduces complexity of the code:

    5 files changed, 249 insertions(+), 494 deletions(-)

  and the performance testing results are encouraging.  Nevertheless we
  need to keep an eye on potential regressions, since this potentially
  affects every SMP workload in existence.

  This work comes from Yuyang Du.

  Other changes:

   - SCHED_DL updates.  (Andrea Parri)

   - Simplify architecture callbacks by removing finish_arch_switch().
     (Peter Zijlstra et al)

   - cputime accounting: guarantee stime + utime == rtime.  (Peter
     Zijlstra)

   - optimize idle CPU wakeups some more - inspired by Facebook server
     loads.  (Mike Galbraith)

   - stop_machine fixes and updates.  (Oleg Nesterov)

   - Introduce the 'trace_sched_waking' tracepoint.  (Peter Zijlstra)

   - sched/numa tweaks.  (Srikar Dronamraju)

   - misc fixes and small cleanups"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits)
  sched/deadline: Fix comment in enqueue_task_dl()
  sched/deadline: Fix comment in push_dl_tasks()
  sched: Change the sched_class::set_cpus_allowed() calling context
  sched: Make sched_class::set_cpus_allowed() unconditional
  sched: Fix a race between __kthread_bind() and sched_setaffinity()
  sched: Ensure a task has a non-normalized vruntime when returning back to CFS
  sched/numa: Fix NUMA_DIRECT topology identification
  tile: Reorganize _switch_to()
  sched, sparc32: Update scheduler comments in copy_thread()
  sched: Remove finish_arch_switch()
  sched, tile: Remove finish_arch_switch
  sched, sh: Fold finish_arch_switch() into switch_to()
  sched, score: Remove finish_arch_switch()
  sched, avr32: Remove finish_arch_switch()
  sched, MIPS: Get rid of finish_arch_switch()
  sched, arm: Remove finish_arch_switch()
  sched/fair: Clean up load average references
  sched/fair: Provide runnable_load_avg back to cfs_rq
  sched/fair: Remove task and group entity load when they are dead
  sched/fair: Init cfs_rq's sched_entity load average
  ...
2015-08-31 20:26:22 -07:00
Jan H. Schönherr
dd9d384375 sched: Fix cpu_active_mask/cpu_online_mask race
There is a race condition in SMP bootup code, which may result
in

    WARNING: CPU: 0 PID: 1 at kernel/workqueue.c:4418
    workqueue_cpu_up_callback()
or
    kernel BUG at kernel/smpboot.c:135!

It can be triggered with a bit of luck in Linux guests running
on busy hosts.

	CPU0                        CPUn
	====                        ====

	_cpu_up()
	  __cpu_up()
				    start_secondary()
				      set_cpu_online()
					cpumask_set_cpu(cpu,
						   to_cpumask(cpu_online_bits));
	  cpu_notify(CPU_ONLINE)
	    <do stuff, see below>
					cpumask_set_cpu(cpu,
						   to_cpumask(cpu_active_bits));

During the various CPU_ONLINE callbacks CPUn is online but not
active. Several things can go wrong at that point, depending on
the scheduling of tasks on CPU0.

Variant 1:

  cpu_notify(CPU_ONLINE)
    workqueue_cpu_up_callback()
      rebind_workers()
        set_cpus_allowed_ptr()

  This call fails because it requires an active CPU; rebind_workers()
  ends with a warning:

    WARNING: CPU: 0 PID: 1 at kernel/workqueue.c:4418
    workqueue_cpu_up_callback()

Variant 2:

  cpu_notify(CPU_ONLINE)
    smpboot_thread_call()
      smpboot_unpark_threads()
       ..
        __kthread_unpark()
          __kthread_bind()
          wake_up_state()
           ..
            select_task_rq()
              select_fallback_rq()

  The ->wake_cpu of the unparked thread is not allowed, making a call
  to select_fallback_rq() necessary. Then, select_fallback_rq() cannot
  find an allowed, active CPU and promptly resets the allowed CPUs, so
  that the task in question ends up on CPU0.

  When those unparked tasks are eventually executed, they run
  immediately into a BUG:

    kernel BUG at kernel/smpboot.c:135!

Just changing the order in which the online/active bits are set
(and adding some memory barriers), would solve the two issues
above. However, it would change the order of operations back to
the one before commit 6acbfb9697 ("sched: Fix hotplug vs.
set_cpus_allowed_ptr()"), thus, reintroducing that particular
problem.

Going further back into history, we have at least the following
commits touching this topic:
- commit 2baab4e904 ("sched: Fix select_fallback_rq() vs cpu_active/cpu_online")
- commit 5fbd036b55 ("sched: Cleanup cpu_active madness")

Together, these give us the following non-working solutions:

  - secondary CPU sets active before online, because active is assumed to
    be a subset of online;

  - secondary CPU sets online before active, because the primary CPU
    assumes that an online CPU is also active;

  - secondary CPU sets online and waits for primary CPU to set active,
    because it might deadlock.

Commit 875ebe940d ("powerpc/smp: Wait until secondaries are
active & online") introduces an arch-specific solution to this
arch-independent problem.

Now, go for a more general solution without explicit waiting and
simply set active twice: once on the secondary CPU after online
was set and once on the primary CPU after online was seen.

set_cpus_allowed_ptr()")

Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <stable@vger.kernel.org>
Cc: Anton Blanchard <anton@samba.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Wilson <msw@amazon.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 6acbfb9697 ("sched: Fix hotplug vs. set_cpus_allowed_ptr()")
Link: http://lkml.kernel.org/r/1439408156-18840-1-git-send-email-jschoenh@amazon.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-25 12:14:39 +02:00
Ingo Molnar
9b9412dc70 Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
Pull RCU changes from Paul E. McKenney:

  - The combination of tree geometry-initialization simplifications
    and OS-jitter-reduction changes to expedited grace periods.
    These two are stacked due to the large number of conflicts
    that would otherwise result.

    [ With one addition, a temporary commit to silence a lockdep false
      positive. Additional changes to the expedited grace-period
      primitives (queued for 4.4) remove the cause of this false
      positive, and therefore include a revert of this temporary commit. ]

  - Documentation updates.

  - Torture-test updates.

  - Miscellaneous fixes.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-12 12:12:12 +02:00
Andrea Parri
ff277d4250 sched/deadline: Fix comment in enqueue_task_dl()
The "dl_boosted" flag is set by comparing *absolute* deadlines
(c.f., rt_mutex_setprio()).

Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1438782979-9057-2-git-send-email-parri.andrea@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-12 12:06:10 +02:00
Andrea Parri
4ffa08ed4c sched/deadline: Fix comment in push_dl_tasks()
The comment is "misleading"; fix it by adapting a comment from
push_rt_tasks().

Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1438782979-9057-1-git-send-email-parri.andrea@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-12 12:06:10 +02:00
Peter Zijlstra
6c37067e27 sched: Change the sched_class::set_cpus_allowed() calling context
Change the calling context of sched_class::set_cpus_allowed() such
that we can assume the task is inactive.

This allows us to easily make changes that affect accounting done by
enqueue/dequeue. This does in fact completely remove
set_cpus_allowed_rt() and greatly reduces set_cpus_allowed_dl().

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dedekind1@gmail.com
Cc: juri.lelli@arm.com
Cc: mgorman@suse.de
Cc: riel@redhat.com
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/20150515154833.667516139@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-12 12:06:10 +02:00
Peter Zijlstra
c5b2803840 sched: Make sched_class::set_cpus_allowed() unconditional
Give every class a set_cpus_allowed() method, this enables some small
optimization in the RT,DL implementation by avoiding a double
cpumask_weight() call.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dedekind1@gmail.com
Cc: juri.lelli@arm.com
Cc: mgorman@suse.de
Cc: riel@redhat.com
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/20150515154833.614517487@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-12 12:06:09 +02:00
Peter Zijlstra
25834c73f9 sched: Fix a race between __kthread_bind() and sched_setaffinity()
Because sched_setscheduler() checks p->flags & PF_NO_SETAFFINITY
without locks, a caller might observe an old value and race with the
set_cpus_allowed_ptr() call from __kthread_bind() and effectively undo
it:

	__kthread_bind()
	  do_set_cpus_allowed()
						<SYSCALL>
						  sched_setaffinity()
						    if (p->flags & PF_NO_SETAFFINITIY)
						    set_cpus_allowed_ptr()
	  p->flags |= PF_NO_SETAFFINITY

Fix the bug by putting everything under the regular scheduler locks.

This also closes a hole in the serialization of task_struct::{nr_,}cpus_allowed.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dedekind1@gmail.com
Cc: juri.lelli@arm.com
Cc: mgorman@suse.de
Cc: riel@redhat.com
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/20150515154833.545640346@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-12 12:06:09 +02:00
Byungchul Park
7855a35ac0 sched: Ensure a task has a non-normalized vruntime when returning back to CFS
Current code ensures that a task has a normalized vruntime when switching away
from the fair class, but it does not ensure the task has a non-normalized
vruntime when switching back to the fair class.

This is an example breaking this consistency:

  1. a task is in fair class and !queued
  2. changes its class to RT class (still !queued)
  3. changes its class to fair class again (still !queued)

Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1439197375-27927-1-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-12 12:06:09 +02:00
Aravind Gopalakrishnan
e237882b8f sched/numa: Fix NUMA_DIRECT topology identification
Systems which have all nodes at a distance of at most 1 hop should be
identified as 'NUMA_DIRECT'.

However, the scheduler incorrectly identifies it as 'NUMA_BACKPLANE'.
This is because 'n' is assigned to sched_max_numa_distance but the
code (mis)interprets it to mean 'number of hops'.

Rik had actually used sched_domains_numa_levels for detecting a
'NUMA_DIRECT' topology:

  http://marc.info/?l=linux-kernel&m=141279712429834&w=2

But that was changed when he removed the hops table in the
subsequent version:

  http://marc.info/?l=linux-kernel&m=141353106106771&w=2

Fixing the issue here.

Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1439256048-3748-1-git-send-email-Aravind.Gopalakrishnan@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-12 12:06:08 +02:00
Peter Zijlstra
3c8e479355 sched: Remove finish_arch_switch()
One less arch hook..

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-04 09:38:33 +02:00
Yuyang Du
7ea241afbf sched/fair: Clean up load average references
For cfs_rq, we have load.weight, runnable_load_avg, and load_avg.
Clean up how they are used:

  - First, as group sched_entity already largely uses load_avg, we now expand
    to use load_avg in all cases.

  - Second, for CPU-wide load balancing, we choose to use runnable_load_avg
    in all cases, which is the same as before this series.

Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1436918682-4971-8-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 12:24:32 +02:00
Yuyang Du
139622343e sched/fair: Provide runnable_load_avg back to cfs_rq
The cfs_rq's load_avg is composed of runnable_load_avg and blocked_load_avg.
Before this series, sometimes the runnable_load_avg is used, and sometimes
the load_avg is used. Completely replacing all uses of runnable_load_avg
with load_avg may be too big a leap, i.e., the blocked_load_avg is concerned
to result in overrated load. Therefore, we get runnable_load_avg back.

The new cfs_rq's runnable_load_avg is improved to be updated with all of the
runnable sched_eneities at the same time, so the one sched_entity updated and
the others stale problem is solved.

Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1436918682-4971-7-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 12:24:31 +02:00
Yuyang Du
1269557889 sched/fair: Remove task and group entity load when they are dead
When task exits or group is destroyed, the entity's load should be
removed from its parent cfs_rq's load. Otherwise, it will take time
for the parent cfs_rq to decay the dead entity's load to 0, which
is not desired.

Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1436918682-4971-6-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 12:24:30 +02:00
Yuyang Du
540247fb5d sched/fair: Init cfs_rq's sched_entity load average
The runnable load and utilization averages of cfs_rq's sched_entity
were not initiated. Like done to a task, give new cfs_rq' sched_entity
start values to heavy its load in infant time.

Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1436918682-4971-5-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 12:24:29 +02:00
Vincent Guittot
6c1d47c082 sched/fair: Implement update_blocked_averages() for CONFIG_FAIR_GROUP_SCHED=n
The load and the utilization of idle CPUs must be updated periodically in
order to decay the blocked part.

If CONFIG_FAIR_GROUP_SCHED is not set, the load and util of idle cpus
are not decayed and stay at the values set before becoming idle.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Link: http://lkml.kernel.org/r/1436918682-4971-4-git-send-email-yuyang.du@intel.com
[ Fixed up the SOB chain. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 12:24:28 +02:00
Yuyang Du
9d89c257df sched/fair: Rewrite runnable load and utilization average tracking
The idea of runnable load average (let runnable time contribute to weight)
was proposed by Paul Turner and Ben Segall, and it is still followed by
this rewrite. This rewrite aims to solve the following issues:

1. cfs_rq's load average (namely runnable_load_avg and blocked_load_avg) is
   updated at the granularity of an entity at a time, which results in the
   cfs_rq's load average is stale or partially updated: at any time, only
   one entity is up to date, all other entities are effectively lagging
   behind. This is undesirable.

   To illustrate, if we have n runnable entities in the cfs_rq, as time
   elapses, they certainly become outdated:

     t0: cfs_rq { e1_old, e2_old, ..., en_old }

   and when we update:

     t1: update e1, then we have cfs_rq { e1_new, e2_old, ..., en_old }

     t2: update e2, then we have cfs_rq { e1_old, e2_new, ..., en_old }

     ...

   We solve this by combining all runnable entities' load averages together
   in cfs_rq's avg, and update the cfs_rq's avg as a whole. This is based
   on the fact that if we regard the update as a function, then:

   w * update(e) = update(w * e) and

   update(e1) + update(e2) = update(e1 + e2), then

   w1 * update(e1) + w2 * update(e2) = update(w1 * e1 + w2 * e2)

   therefore, by this rewrite, we have an entirely updated cfs_rq at the
   time we update it:

     t1: update cfs_rq { e1_new, e2_new, ..., en_new }

     t2: update cfs_rq { e1_new, e2_new, ..., en_new }

     ...

2. cfs_rq's load average is different between top rq->cfs_rq and other
   task_group's per CPU cfs_rqs in whether or not blocked_load_average
   contributes to the load.

   The basic idea behind runnable load average (the same for utilization)
   is that the blocked state is taken into account as opposed to only
   accounting for the currently runnable state. Therefore, the average
   should include both the runnable/running and blocked load averages.
   This rewrite does that.

   In addition, we also combine runnable/running and blocked averages
   of all entities into the cfs_rq's average, and update it together at
   once. This is based on the fact that:

     update(runnable) + update(blocked) = update(runnable + blocked)

   This significantly reduces the code as we don't need to separately
   maintain/update runnable/running load and blocked load.

3. How task_group entities' share is calculated is complex and imprecise.

   We reduce the complexity in this rewrite to allow a very simple rule:
   the task_group's load_avg is aggregated from its per CPU cfs_rqs's
   load_avgs. Then group entity's weight is simply proportional to its
   own cfs_rq's load_avg / task_group's load_avg. To illustrate,

   if a task_group has { cfs_rq1, cfs_rq2, ..., cfs_rqn }, then,

   task_group_avg = cfs_rq1_avg + cfs_rq2_avg + ... + cfs_rqn_avg, then

   cfs_rqx's entity's share = cfs_rqx_avg / task_group_avg * task_group's share

To sum up, this rewrite in principle is equivalent to the current one, but
fixes the issues described above. Turns out, it significantly reduces the
code complexity and hence increases clarity and efficiency. In addition,
the new averages are more smooth/continuous (no spurious spikes and valleys)
and updated more consistently and quickly to reflect the load dynamics.

As a result, we have less load tracking overhead, better performance,
and especially better power efficiency due to more balanced load.

Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1436918682-4971-3-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 12:21:29 +02:00
Yuyang Du
cd126afe83 sched/fair: Remove rq's runnable avg
The current rq->avg is not used at all since its merge into the kernel,
and the code is in the scheduler's hot path, so remove it.

Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1436918682-4971-2-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 12:21:28 +02:00
Konstantin Khlebnikov
fe32d3cd5e sched/preempt: Fix cond_resched_lock() and cond_resched_softirq()
These functions check should_resched() before unlocking spinlock/bh-enable:
preempt_count always non-zero => should_resched() always returns false.
cond_resched_lock() worked iff spin_needbreak is set.

This patch adds argument "preempt_offset" to should_resched().

preempt_count offset constants for that:

  PREEMPT_DISABLE_OFFSET  - offset after preempt_disable()
  PREEMPT_LOCK_OFFSET     - offset after spin_lock()
  SOFTIRQ_DISABLE_OFFSET  - offset after local_bh_distable()
  SOFTIRQ_LOCK_OFFSET     - offset after spin_lock_bh()

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Graf <agraf@suse.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: bdb4380658 ("sched: Extract the basic add/sub preempt_count modifiers")
Link: http://lkml.kernel.org/r/20150715095204.12246.98268.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 12:21:24 +02:00
Mike Galbraith
63b0e9edce sched/fair: Beef up wake_wide()
Josef Bacik reported that Facebook sees better performance with their
1:N load (1 dispatch/node, N workers/node) when carrying an old patch
to try very hard to wake to an idle CPU.  While looking at wake_wide(),
I noticed that it doesn't pay attention to the wakeup of a many partner
waker, returning 1 only when waking one of its many partners.

Correct that, letting explicit domain flags override the heuristic.

While at it, adjust task_struct bits, we don't need a 64-bit counter.

Tested-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
[ Tidy things up. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-team<Kernel-team@fb.com>
Cc: morten.rasmussen@arm.com
Cc: riel@redhat.com
Link: http://lkml.kernel.org/r/1436888390.7983.49.camel@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 12:21:23 +02:00
Peter Zijlstra
fbd705a0c6 sched: Introduce the 'trace_sched_waking' tracepoint
Mathieu reported that since 317f394160 ("sched: Move the second half
of ttwu() to the remote cpu") trace_sched_wakeup() can happen out of
context of the waker.

This is a problem when you want to analyse wakeup paths because it is
now very hard to correlate the wakeup event to whoever issued the
wakeup.

OTOH trace_sched_wakeup() is issued at the point where we set
p->state = TASK_RUNNING, which is right were we hand the task off to
the scheduler, so this is an important point when looking at
scheduling behaviour, up to here its been the wakeup path everything
hereafter is due to scheduler policy.

To bridge this gap, introduce a second tracepoint: trace_sched_waking.
It is guaranteed to be called in the waker context.

Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Francis Giraldeau <francis.giraldeau@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150609091336.GQ3644@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 12:21:22 +02:00
Peter Zijlstra
9d7fb04276 sched/cputime: Guarantee stime + utime == rtime
While the current code guarantees monotonicity for stime and utime
independently of one another, it does not guarantee that the sum of
both is equal to the total time we started out with.

This confuses things (and peoples) who look at this sum, like top, and
will report >100% usage followed by a matching period of 0%.

Rework the code to provide both individual monotonicity and a coherent
sum.

Suggested-by: Fredrik Markstrom <fredrik.markstrom@gmail.com>
Reported-by: Fredrik Markstrom <fredrik.markstrom@gmail.com>
Tested-by: Fredrik Markstrom <fredrik.markstrom@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: jason.low2@hp.com
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 12:21:21 +02:00
Markus Elfring
781b020342 sched, sysctl: Delete an unnecessary check before unregister_sysctl_table()
The unregister_sysctl_table() function tests whether its argument is NULL
and then returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/5597877E.3060503@users.sourceforge.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 12:21:21 +02:00
Xunlei Pang
3fe33bcdd3 sched/deadline: Remove a redundant condition from task_woken_dl()
'p' has been already queued at this point, so "!task_running(rq, p)"
and "p->nr_cpus_allowed > 1" imply that "has_pushable_dl_tasks(rq)"
is true, so it can be removed.

Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1435995563-3723-2-git-send-email-xlpang@126.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 12:21:20 +02:00
Xunlei Pang
8fd373548e sched/rt: Remove a redundant condition from task_woken_rt()
'p' has been already queued at this point, so "!task_running(rq, p)"
and "p->nr_cpus_allowed > 1" imply that "has_pushable_tasks(rq)" is
true, so it can be removed.

Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1435995563-3723-1-git-send-email-xlpang@126.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 12:21:19 +02:00
Yuyang Du
985d3a4c11 sched/fair: Avoid pulling all tasks in idle balancing
In idle balancing where a CPU going idle pulls tasks from another CPU,
a livelock may happen if the CPU pulls all tasks from another, makes
it idle, and this iterates. So just avoid this.

Reported-by: Rabin Vincent <rabin.vincent@axis.com>
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150705221151.GF5197@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 12:21:19 +02:00
Peter Zijlstra
e33886b38c locking/static_keys: Add static_key_{en,dis}able() helpers
Add two helpers to make it easier to treat the refcount as boolean.

Suggested-by: Jason Baron <jasonbaron0@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03 11:34:14 +02:00
Frederic Weisbecker
de734f89b6 nohz: Remove useless argument on tick_nohz_task_switch()
Leftover from early code.

Cc: Christoph Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2015-07-29 15:45:01 +02:00
Paul E. McKenney
f78f5b90c4 rcu: Rename rcu_lockdep_assert() to RCU_LOCKDEP_WARN()
This commit renames rcu_lockdep_assert() to RCU_LOCKDEP_WARN() for
consistency with the WARN() series of macros.  This also requires
inverting the sense of the conditional, which this commit also does.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
2015-07-22 15:27:32 -07:00
Lucas Stach
63caae8480 sched/idle: Move latency tracing stop/start calls deeper inside the idle loop
Make sure to stop tracing only once we are past a point where
all latency tracing events have been processed (irqs are not
enabled again). This has the slight advantage of capturing more
latency related events in the idle path, but most importantly it
makes sure that latency tracing doesn't get re-enabled
inadvertently when new events are coming in.

This makes the irqsoff latency tracer useful again, as we stop
capturing CPU sleep time as IRQ latency.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel@pengutronix.de
Cc: patchwork-lst@pengutronix.de
Link: http://lkml.kernel.org/r/1437410090-3747-1-git-send-email-l.stach@pengutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-21 08:18:51 +02:00
Aleksa Sarai
7e47682ea5 cgroup: allow a cgroup subsystem to reject a fork
Add a new cgroup subsystem callback can_fork that conditionally
states whether or not the fork is accepted or rejected by a cgroup
policy. In addition, add a cancel_fork callback so that if an error
occurs later in the forking process, any state modified by can_fork can
be reverted.

Allow for a private opaque pointer to be passed from cgroup_can_fork to
cgroup_post_fork, allowing for the fork state to be stored by each
subsystem separately.

Also add a tagging system for cgroup_subsys.h to allow for CGROUP_<TAG>
enumerations to be be defined and used. In addition, explicitly add a
CGROUP_CANFORK_COUNT macro to make arrays easier to define.

This is in preparation for implementing the pids cgroup subsystem.

Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2015-07-14 17:29:23 -04:00
Byungchul Park
399595f248 sched/fair: Fix a comment reflecting function name change
update_cfs_rq_load_contribution() was changed to
__update_cfs_rq_tg_load_contrib() - sync up the commit in
calc_tg_weight() too.

Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1436187062-19658-1-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-07 08:46:11 +02:00
Boqun Feng
8e2b0bf397 sched/fair: Clean up the __sched_period() code
Since commit:

  4bf0b77158 ("sched: remove do_div() from __sched_slice()")

... the logic of __sched_period() can be implemented as a single if-else
without any local variables, so this patch cleans it up with an if-else
statement, which expresses the function's logic straightforwardly.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1435847152-29543-1-git-send-email-boqun.feng@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-07 08:46:10 +02:00
Srikar Dronamraju
44dcb04f0e sched/numa: Consider 'imbalance_pct' when comparing loads in numa_has_capacity()
This is consistent with all other load balancing instances where we
absorb unfairness upto env->imbalance_pct. Absorbing unfairness upto
env->imbalance_pct allows to pull and retain task to their preferred
nodes.

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1434455762-30857-3-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-07 08:46:10 +02:00
Srikar Dronamraju
2a1ed24ce9 sched/numa: Prefer NUMA hotness over cache hotness
The current load balancer may not try to prevent a task from moving
out of a preferred node to a less preferred node. The reason for this
being:

 - Since sched features NUMA and NUMA_RESIST_LOWER are disabled by
   default, migrate_degrades_locality() always returns false.

 - Even if NUMA_RESIST_LOWER were to be enabled, if its cache hot,
   migrate_degrades_locality() never gets called.

The above behaviour can mean that tasks can move out of their
preferred node but they may be eventually be brought back to their
preferred node by numa balancer (due to higher numa faults).

To avoid the above, this commit merges migrate_degrades_locality() and
migrate_improves_locality(). It also replaces 3 sched features NUMA,
NUMA_FAVOUR_HIGHER and NUMA_RESIST_LOWER by a single sched feature
NUMA.

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Mike Galbraith <efault@gmx.de>
Link: http://lkml.kernel.org/r/1434455762-30857-2-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-07 08:46:10 +02:00
bsegall@google.com
6dfec8d949 sched/numa: Check sched_feat(NUMA) in migrate_improves_locality()
migrate_improves_locality checked sched_feat(NUMA_FAVOUR_HIGHER) but not
sched_feat(NUMA), so disabling just the NUMA feature would leave it
working off of old data.

Signed-off-by: Ben Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/xm26si9rtqbm.fsf@sword-of-the-dawn.mtv.corp.google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-07 08:46:09 +02:00
Cong Wang
d49db342f0 sched/fair: Test list head instead of list entry in throttle_cfs_rq()
According to the comments, we need to test if this is
the first throttled task, however, list_empty() tests on
the entry cfs_rq->throttled_list, not the head, this is wrong.

This is a bug because we don't re-init the list entry after
removing it from the list, so list_empty() could return false
even if the list is really empty.

Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Cong Wang <cwang@twopensource.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ben Segall <bsegall@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1435174907-432-1-git-send-email-xiyou.wangcong@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-06 14:15:08 +02:00
Linus Torvalds
1b3618b60a Except for the preempt notifiers fix, these are all small bugfixes
that could have been waited for -rc2.  Sending them now since I
 was taking care of Peter's patch anyway.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm fixes from Paolo Bonzini:
 "Except for the preempt notifiers fix, these are all small bugfixes
  that could have been waited for -rc2.  Sending them now since I was
  taking care of Peter's patch anyway"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  kvm: add hyper-v crash msrs values
  KVM: x86: remove data variable from kvm_get_msr_common
  KVM: s390: virtio-ccw: don't overwrite config space values
  KVM: x86: keep track of LVT0 changes under APICv
  KVM: x86: properly restore LVT0
  KVM: x86: make vapics_in_nmi_mode atomic
  sched, preempt_notifier: separate notifier registration from static_key inc/dec
2015-07-04 11:29:59 -07:00
Linus Torvalds
22a093b2fb Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
 "Debug info and other statistics fixes and related enhancements"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/numa: Fix numa balancing stats in /proc/pid/sched
  sched/numa: Show numa_group ID in /proc/sched_debug task listings
  sched/debug: Move print_cfs_rq() declaration to kernel/sched/sched.h
  sched/stat: Expose /proc/pid/schedstat if CONFIG_SCHED_INFO=y
  sched/stat: Simplify the sched_info accounting dependency
2015-07-04 08:56:53 -07:00