linux-stable.git/kernel/sched/core.c, branch v3.15.9 Linux kernel stable tree printk: rename printk_sched to printk_deferred 2014-08-07T23:53:52+00:00 John Stultz john.stultz@linaro.org 2014-06-04T23:11:40+00:00 3a5e0137b5d7c58f6eb66a263fc66965b758b76f commit aac74dc495456412c4130a1167ce4beb6c1f0b38 upstream. After learning we'll need some sort of deferred printk functionality in the timekeeping core, Peter suggested we rename the printk_sched function so it can be reused by needed subsystems. This only changes the function name. No logic changes. Signed-off-by: John Stultz <john.stultz@linaro.org> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Cc: Jan Kara <jack@suse.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Jiri Bohac <jbohac@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit aac74dc495456412c4130a1167ce4beb6c1f0b38 upstream.

After learning we'll need some sort of deferred printk functionality in
the timekeeping core, Peter suggested we rename the printk_sched function
so it can be reused by needed subsystems.

This only changes the function name. No logic changes.

Signed-off-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-06-06T16:53:32+00:00 Linus Torvalds torvalds@linux-foundation.org 2014-06-06T16:53:32+00:00 d54d14bfb49f0b61aed9f20cb84cb692566cf83b Pull scheduler fixes from Ingo Molnar: "Four misc fixes: each was deemed serious enough to warrant v3.15 inclusion" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/fair: Fix tg_set_cfs_bandwidth() deadlock on rq->lock sched/dl: Fix race in dl_task_timer() sched: Fix sched_policy < 0 comparison sched/numa: Fix use of spin_{un}lock_irq() when interrupts are disabled 
Pull scheduler fixes from Ingo Molnar:
 "Four misc fixes: each was deemed serious enough to warrant v3.15
  inclusion"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Fix tg_set_cfs_bandwidth() deadlock on rq->lock
  sched/dl: Fix race in dl_task_timer()
  sched: Fix sched_policy < 0 comparison
  sched/numa: Fix use of spin_{un}lock_irq() when interrupts are disabled
sched/fair: Fix tg_set_cfs_bandwidth() deadlock on rq->lock 2014-06-05T09:51:34+00:00 Roman Gushchin klamm@yandex-team.ru 2014-05-19T11:10:09+00:00 09dc4ab03936df5c5aa711d27c81283c6d09f495 tg_set_cfs_bandwidth() sets cfs_b->timer_active to 0 to force the period timer restart. It's not safe, because can lead to deadlock, described in commit 927b54fccbf0: "__start_cfs_bandwidth calls hrtimer_cancel while holding rq->lock, waiting for the hrtimer to finish. However, if sched_cfs_period_timer runs for another loop iteration, the hrtimer can attempt to take rq->lock, resulting in deadlock." Three CPUs must be involved: CPU0 CPU1 CPU2 take rq->lock period timer fired ... take cfs_b lock ... ... tg_set_cfs_bandwidth() throttle_cfs_rq() release cfs_b lock take cfs_b lock ... distribute_cfs_runtime() timer_active = 0 take cfs_b->lock wait for rq->lock ... __start_cfs_bandwidth() {wait for timer callback break if timer_active == 1} So, CPU0 and CPU1 are deadlocked. Instead of resetting cfs_b->timer_active, tg_set_cfs_bandwidth can wait for period timer callbacks (ignoring cfs_b->timer_active) and restart the timer explicitly. Signed-off-by: Roman Gushchin <klamm@yandex-team.ru> Reviewed-by: Ben Segall <bsegall@google.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/87wqdi9g8e.wl\%klamm@yandex-team.ru Cc: pjt@google.com Cc: chris.j.arges@canonical.com Cc: gregkh@linuxfoundation.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> 
tg_set_cfs_bandwidth() sets cfs_b->timer_active to 0 to
force the period timer restart. It's not safe, because
can lead to deadlock, described in commit 927b54fccbf0:
"__start_cfs_bandwidth calls hrtimer_cancel while holding rq->lock,
waiting for the hrtimer to finish. However, if sched_cfs_period_timer
runs for another loop iteration, the hrtimer can attempt to take
rq->lock, resulting in deadlock."

Three CPUs must be involved:

  CPU0               CPU1                         CPU2
  take rq->lock      period timer fired
  ...                take cfs_b lock
  ...                ...                          tg_set_cfs_bandwidth()
  throttle_cfs_rq()  release cfs_b lock           take cfs_b lock
  ...                distribute_cfs_runtime()     timer_active = 0
  take cfs_b->lock   wait for rq->lock            ...
  __start_cfs_bandwidth()
  {wait for timer callback
   break if timer_active == 1}

So, CPU0 and CPU1 are deadlocked.

Instead of resetting cfs_b->timer_active, tg_set_cfs_bandwidth can
wait for period timer callbacks (ignoring cfs_b->timer_active) and
restart the timer explicitly.

Signed-off-by: Roman Gushchin <klamm@yandex-team.ru>
Reviewed-by: Ben Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/87wqdi9g8e.wl\%klamm@yandex-team.ru
Cc: pjt@google.com
Cc: chris.j.arges@canonical.com
Cc: gregkh@linuxfoundation.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
sched: Fix sched_policy < 0 comparison 2014-06-05T09:07:43+00:00 Richard Weinberger richard@nod.at 2014-06-02T20:38:34+00:00 b14ed2c273f8ab872ae4e6735fe5ab09cb14b8c3 attr.sched_policy is u32, therefore a comparison against < 0 is never true. Fix this by casting sched_policy to int. This issue was reported by coverity CID 1219934. Fixes: dbdb22754fde ("sched: Disallow sched_attr::sched_policy < 0") Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1401741514-7045-1-git-send-email-richard@nod.at Signed-off-by: Ingo Molnar <mingo@kernel.org> 
attr.sched_policy is u32, therefore a comparison against < 0 is never true.
Fix this by casting sched_policy to int.

This issue was reported by coverity CID 1219934.

Fixes: dbdb22754fde ("sched: Disallow sched_attr::sched_policy < 0")
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1401741514-7045-1-git-send-email-richard@nod.at
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-06-02T01:26:59+00:00 Linus Torvalds torvalds@linux-foundation.org 2014-06-02T01:26:59+00:00 32439700fe1c0fc3c2d3f2aedd3ad6707c88b8ba Pull scheduler fixes from Ingo Molnar: "Various fixlets, mostly related to the (root-only) SCHED_DEADLINE policy, but also a hotplug bug fix and a fix for a NR_CPUS related overallocation bug causing a suspend/resume regression" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched: Fix hotplug vs. set_cpus_allowed_ptr() sched/cpupri: Replace NR_CPUS arrays sched/deadline: Replace NR_CPUS arrays sched/deadline: Restrict user params max value to 2^63 ns sched/deadline: Change sched_getparam() behaviour vs SCHED_DEADLINE sched: Disallow sched_attr::sched_policy < 0 sched: Make sched_setattr() correctly return -EFBIG 
Pull scheduler fixes from Ingo Molnar:
 "Various fixlets, mostly related to the (root-only) SCHED_DEADLINE
  policy, but also a hotplug bug fix and a fix for a NR_CPUS related
  overallocation bug causing a suspend/resume regression"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Fix hotplug vs. set_cpus_allowed_ptr()
  sched/cpupri: Replace NR_CPUS arrays
  sched/deadline: Replace NR_CPUS arrays
  sched/deadline: Restrict user params max value to 2^63 ns
  sched/deadline: Change sched_getparam() behaviour vs SCHED_DEADLINE
  sched: Disallow sched_attr::sched_policy < 0
  sched: Make sched_setattr() correctly return -EFBIG
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-05-23T17:04:04+00:00 Linus Torvalds torvalds@linux-foundation.org 2014-05-23T17:04:04+00:00 f02f79dbcb9c0326588c1cbe24b40887737e71d3 Pull scheduler fixes from Ingo Molnar: "The biggest commit is an irqtime accounting loop latency fix, the rest are misc fixes all over the place: deadline scheduling, docs, numa, balancer and a bad to-idle latency fix" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/numa: Initialize newidle balance stats in sd_numa_init() sched: Fix updating rq->max_idle_balance_cost and rq->next_balance in idle_balance() sched: Skip double execution of pick_next_task_fair() sched: Use CPUPRI_NR_PRIORITIES instead of MAX_RT_PRIO in cpupri check sched/deadline: Fix memory leak sched/deadline: Fix sched_yield() behavior sched: Sanitize irq accounting madness sched/docbook: Fix 'make htmldocs' warnings caused by missing description 
Pull scheduler fixes from Ingo Molnar:
 "The biggest commit is an irqtime accounting loop latency fix, the rest
  are misc fixes all over the place: deadline scheduling, docs, numa,
  balancer and a bad to-idle latency fix"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/numa: Initialize newidle balance stats in sd_numa_init()
  sched: Fix updating rq->max_idle_balance_cost and rq->next_balance in idle_balance()
  sched: Skip double execution of pick_next_task_fair()
  sched: Use CPUPRI_NR_PRIORITIES instead of MAX_RT_PRIO in cpupri check
  sched/deadline: Fix memory leak
  sched/deadline: Fix sched_yield() behavior
  sched: Sanitize irq accounting madness
  sched/docbook: Fix 'make htmldocs' warnings caused by missing description
sched: Fix hotplug vs. set_cpus_allowed_ptr() 2014-05-22T08:21:31+00:00 Lai Jiangshan laijs@cn.fujitsu.com 2014-05-16T03:50:42+00:00 6acbfb96976fc3350e30d964acb1dbbdf876d55e Lai found that: WARNING: CPU: 1 PID: 13 at arch/x86/kernel/smp.c:124 native_smp_send_reschedule+0x2d/0x4b() ... migration_cpu_stop+0x1d/0x22 was caused by set_cpus_allowed_ptr() assuming that cpu_active_mask is always a sub-set of cpu_online_mask. This isn't true since 5fbd036b552f ("sched: Cleanup cpu_active madness"). So set active and online at the same time to avoid this particular problem. Fixes: 5fbd036b552f ("sched: Cleanup cpu_active madness") Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Gautham R. Shenoy <ego@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michael wang <wangyun@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Cc: Toshi Kani <toshi.kani@hp.com> Link: http://lkml.kernel.org/r/53758B12.8060609@cn.fujitsu.com Signed-off-by: Ingo Molnar <mingo@kernel.org> 
Lai found that:

  WARNING: CPU: 1 PID: 13 at arch/x86/kernel/smp.c:124 native_smp_send_reschedule+0x2d/0x4b()
  ...
  migration_cpu_stop+0x1d/0x22

was caused by set_cpus_allowed_ptr() assuming that cpu_active_mask is
always a sub-set of cpu_online_mask.

This isn't true since 5fbd036b552f ("sched: Cleanup cpu_active madness").

So set active and online at the same time to avoid this particular
problem.

Fixes: 5fbd036b552f ("sched: Cleanup cpu_active madness")
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael wang <wangyun@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Link: http://lkml.kernel.org/r/53758B12.8060609@cn.fujitsu.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
sched/deadline: Restrict user params max value to 2^63 ns 2014-05-22T08:21:27+00:00 Juri Lelli juri.lelli@gmail.com 2014-05-13T12:11:31+00:00 b0827819b0da4acfbc1df1e05edcf50efd07cbd1 Michael Kerrisk noticed that creating SCHED_DEADLINE reservations with certain parameters (e.g, a runtime of something near 2^64 ns) can cause a system freeze for some amount of time. The problem is that in the interface we have u64 sched_runtime; while internally we need to have a signed runtime (to cope with budget overruns) s64 runtime; At the time we setup a new dl_entity we copy the first value in the second. The cast turns out with negative values when sched_runtime is too big, and this causes the scheduler to go crazy right from the start. Moreover, considering how we deal with deadlines wraparound (s64)(a - b) < 0 we also have to restrict acceptable values for sched_{deadline,period}. This patch fixes the thing checking that user parameters are always below 2^63 ns (still large enough for everyone). It also rewrites other conditions that we check, since in __checkparam_dl we don't have to deal with deadline wraparounds and what we have now erroneously fails when the difference between values is too big. Reported-by: Michael Kerrisk <mtk.manpages@gmail.com> Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Juri Lelli <juri.lelli@gmail.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: <stable@vger.kernel.org> Cc: Dario Faggioli<raistlin@linux.it> Cc: Dave Jones <davej@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20140513141131.20d944f81633ee937f256385@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> 
Michael Kerrisk noticed that creating SCHED_DEADLINE reservations
with certain parameters (e.g, a runtime of something near 2^64 ns)
can cause a system freeze for some amount of time.

The problem is that in the interface we have

 u64 sched_runtime;

while internally we need to have a signed runtime (to cope with
budget overruns)

 s64 runtime;

At the time we setup a new dl_entity we copy the first value in
the second. The cast turns out with negative values when
sched_runtime is too big, and this causes the scheduler to go crazy
right from the start.

Moreover, considering how we deal with deadlines wraparound

 (s64)(a - b) < 0

we also have to restrict acceptable values for sched_{deadline,period}.

This patch fixes the thing checking that user parameters are always
below 2^63 ns (still large enough for everyone).

It also rewrites other conditions that we check, since in
__checkparam_dl we don't have to deal with deadline wraparounds
and what we have now erroneously fails when the difference between
values is too big.

Reported-by: Michael Kerrisk <mtk.manpages@gmail.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: Dario Faggioli<raistlin@linux.it>
Cc: Dave Jones <davej@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140513141131.20d944f81633ee937f256385@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
sched/deadline: Change sched_getparam() behaviour vs SCHED_DEADLINE 2014-05-22T08:21:26+00:00 Peter Zijlstra peterz@infradead.org 2014-05-12T20:50:34+00:00 ce5f7f8200ca2504f6f290044393d73ca314965a The way we read POSIX one should only call sched_getparam() when sched_getscheduler() returns either SCHED_FIFO or SCHED_RR. Given that we currently return sched_param::sched_priority=0 for all others, extend the same behaviour to SCHED_DEADLINE. Requested-by: Michael Kerrisk <mtk.manpages@gmail.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Dario Faggioli <raistlin@linux.it> Cc: linux-man <linux-man@vger.kernel.org> Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> Cc: Juri Lelli <juri.lelli@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/20140512205034.GH13467@laptop.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org> 
The way we read POSIX one should only call sched_getparam() when
sched_getscheduler() returns either SCHED_FIFO or SCHED_RR.

Given that we currently return sched_param::sched_priority=0 for all
others, extend the same behaviour to SCHED_DEADLINE.

Requested-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Dario Faggioli <raistlin@linux.it>
Cc: linux-man <linux-man@vger.kernel.org>
Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20140512205034.GH13467@laptop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
sched: Disallow sched_attr::sched_policy < 0 2014-05-22T08:21:26+00:00 Peter Zijlstra peterz@infradead.org 2014-05-09T08:49:03+00:00 dbdb22754fde671dc93d2fae06f8be113d47f2fb The scheduler uses policy=-1 to preserve the current policy state to implement sys_sched_setparam(), this got exposed to userspace by accident through sys_sched_setattr(), cure this. Reported-by: Michael Kerrisk <mtk.manpages@gmail.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michael Kerrisk <mtk.manpages@gmail.com> Cc: <stable@vger.kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20140509085311.GJ30445@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org> 
The scheduler uses policy=-1 to preserve the current policy state to
implement sys_sched_setparam(), this got exposed to userspace by
accident through sys_sched_setattr(), cure this.

Reported-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: <stable@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140509085311.GJ30445@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>