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  1. 04 2月, 2015 7 次提交
  3. 31 1月, 2015 4 次提交
  5. 28 1月, 2015 2 次提交
    • M
      sched: Fix crash if cpuset_cpumask_can_shrink() is passed an empty cpumask · bb2bc55a
      由 Mike Galbraith 提交于 
      While creating an exclusive cpuset, we passed cpuset_cpumask_can_shrink()
an empty cpumask (cur), and dl_bw_of(cpumask_any(cur)) made boom with it:

 CPU: 0 PID: 6942 Comm: shield.sh Not tainted 3.19.0-master #19
 Hardware name: MEDIONPC MS-7502/MS-7502, BIOS 6.00 PG 12/26/2007
 task: ffff880224552450 ti: ffff8800caab8000 task.ti: ffff8800caab8000
 RIP: 0010:[<ffffffff81073846>]  [<ffffffff81073846>] cpuset_cpumask_can_shrink+0x56/0xb0
 [...]
 Call Trace:
  [<ffffffff810cb82a>] validate_change+0x18a/0x200
  [<ffffffff810cc877>] cpuset_write_resmask+0x3b7/0x720
  [<ffffffff810c4d58>] cgroup_file_write+0x38/0x100
  [<ffffffff811d953a>] kernfs_fop_write+0x12a/0x180
  [<ffffffff8116e1a3>] vfs_write+0xb3/0x1d0
  [<ffffffff8116ed06>] SyS_write+0x46/0xb0
  [<ffffffff8159ced6>] system_call_fastpath+0x16/0x1b
Signed-off-by: NMike Galbraith <umgwanakikbuti@gmail.com>
Acked-by: NZefan Li <lizefan@huawei.com>
Fixes: f82f8042 ("sched/deadline: Ensure that updates to exclusive cpusets don't break AC")
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1422417235.5716.5.camel@marge.simpson.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
      bb2bc55a
    • J
      sched/fair: Avoid using uninitialized variable in preferred_group_nid() · 81907478
      由 Jan Beulich 提交于 
      At least some gcc versions - validly afaict - warn about potentially
using max_group uninitialized: There's no way the compiler can prove
that the body of the conditional where it and max_faults get set/
updated gets executed; in fact, without knowing all the details of
other scheduler code, I can't prove this either.

Generally the necessary change would appear to be to clear max_group
prior to entering the inner loop, and break out of the outer loop when
it ends up being all clear after the inner one. This, however, seems
inefficient, and afaict the same effect can be achieved by exiting the
outer loop when max_faults is still zero after the inner loop.

[ mingo: changed the solution to zero initialization: uninitialized_var()
  needs to die, as it's an actively dangerous construct: if in the future
  a known-proven-good piece of code is changed to have a true, buggy
  uninitialized variable, the compiler warning is then supressed...

  The better long term solution is to clean up the code flow, so that
  even simple minded compilers (and humans!) are able to read it without
  getting a headache.  ]
Signed-off-by: NJan Beulich <jbeulich@suse.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/54C2139202000078000588F7@mail.emea.novell.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      81907478
  7. 14 1月, 2015 8 次提交
  9. 09 1月, 2015 4 次提交
    • T
      sched/fair: Fix RCU stall upon -ENOMEM in sched_create_group() · 7f1a169b
      由 Tetsuo Handa 提交于 
      When alloc_fair_sched_group() in sched_create_group() fails,
free_sched_group() is called, and free_fair_sched_group() is called by
free_sched_group(). Since destroy_cfs_bandwidth() is called by
free_fair_sched_group() without calling init_cfs_bandwidth(),
RCU stall occurs at hrtimer_cancel():

  INFO: rcu_sched self-detected stall on CPU { 1}  (t=60000 jiffies g=13074 c=13073 q=0)
  Task dump for CPU 1:
  (fprintd)       R  running task        0  6249      1 0x00000088
  ...
  Call Trace:
   <IRQ>  [<ffffffff81094988>] sched_show_task+0xa8/0x110
   [<ffffffff81097acd>] dump_cpu_task+0x3d/0x50
   [<ffffffff810c3a80>] rcu_dump_cpu_stacks+0x90/0xd0
   [<ffffffff810c7751>] rcu_check_callbacks+0x491/0x700
   [<ffffffff810cbf2b>] update_process_times+0x4b/0x80
   [<ffffffff810db046>] tick_sched_handle.isra.20+0x36/0x50
   [<ffffffff810db0a2>] tick_sched_timer+0x42/0x70
   [<ffffffff810ccb19>] __run_hrtimer+0x69/0x1a0
   [<ffffffff810db060>] ? tick_sched_handle.isra.20+0x50/0x50
   [<ffffffff810ccedf>] hrtimer_interrupt+0xef/0x230
   [<ffffffff810452cb>] local_apic_timer_interrupt+0x3b/0x70
   [<ffffffff8164a465>] smp_apic_timer_interrupt+0x45/0x60
   [<ffffffff816485bd>] apic_timer_interrupt+0x6d/0x80
   <EOI>  [<ffffffff810cc588>] ? lock_hrtimer_base.isra.23+0x18/0x50
   [<ffffffff81193cf1>] ? __kmalloc+0x211/0x230
   [<ffffffff810cc9d2>] hrtimer_try_to_cancel+0x22/0xd0
   [<ffffffff81193cf1>] ? __kmalloc+0x211/0x230
   [<ffffffff810ccaa2>] hrtimer_cancel+0x22/0x30
   [<ffffffff810a3cb5>] free_fair_sched_group+0x25/0xd0
   [<ffffffff8108df46>] free_sched_group+0x16/0x40
   [<ffffffff810971bb>] sched_create_group+0x4b/0x80
   [<ffffffff810aa383>] sched_autogroup_create_attach+0x43/0x1c0
   [<ffffffff8107dc9c>] sys_setsid+0x7c/0x110
   [<ffffffff81647729>] system_call_fastpath+0x12/0x17

Check whether init_cfs_bandwidth() was called before calling
destroy_cfs_bandwidth().
Signed-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
[ Move the check into destroy_cfs_bandwidth() to aid compilability. ]
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Paul Turner <pjt@google.com>
Cc: Ben Segall <bsegall@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/201412252210.GCC30204.SOMVFFOtQJFLOH@I-love.SAKURA.ne.jpSigned-off-by: NIngo Molnar <mingo@kernel.org>
      7f1a169b
    • L
      sched/deadline: Avoid double-accounting in case of missed deadlines · 269ad801
      由 Luca Abeni 提交于 
      The dl_runtime_exceeded() function is supposed to ckeck if
a SCHED_DEADLINE task must be throttled, by checking if its
current runtime is <= 0. However, it also checks if the
scheduling deadline has been missed (the current time is
larger than the current scheduling deadline), further
decreasing the runtime if this happens.
This "double accounting" is wrong:

- In case of partitioned scheduling (or single CPU), this
  happens if task_tick_dl() has been called later than expected
  (due to small HZ values). In this case, the current runtime is
  also negative, and replenish_dl_entity() can take care of the
  deadline miss by recharging the current runtime to a value smaller
  than dl_runtime

- In case of global scheduling on multiple CPUs, scheduling
  deadlines can be missed even if the task did not consume more
  runtime than expected, hence penalizing the task is wrong

This patch fix this problem by throttling a SCHED_DEADLINE task
only when its runtime becomes negative, and not modifying the runtime
Signed-off-by: NLuca Abeni <luca.abeni@unitn.it>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NJuri Lelli <juri.lelli@gmail.com>
Cc: <stable@vger.kernel.org>
Cc: Dario Faggioli <raistlin@linux.it>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1418813432-20797-3-git-send-email-luca.abeni@unitn.itSigned-off-by: NIngo Molnar <mingo@kernel.org>
      269ad801
    • L
      sched/deadline: Fix migration of SCHED_DEADLINE tasks · 6a503c3b
      由 Luca Abeni 提交于 
      According to global EDF, tasks should be migrated between runqueues
without checking if their scheduling deadlines and runtimes are valid.
However, SCHED_DEADLINE currently performs such a check:
a migration happens doing:

	deactivate_task(rq, next_task, 0);
	set_task_cpu(next_task, later_rq->cpu);
	activate_task(later_rq, next_task, 0);

which ends up calling dequeue_task_dl(), setting the new CPU, and then
calling enqueue_task_dl().

enqueue_task_dl() then calls enqueue_dl_entity(), which calls
update_dl_entity(), which can modify scheduling deadline and runtime,
breaking global EDF scheduling.

As a result, some of the properties of global EDF are not respected:
for example, a taskset {(30, 80), (40, 80), (120, 170)} scheduled on
two cores can have unbounded response times for the third task even
if 30/80+40/80+120/170 = 1.5809 < 2

This can be fixed by invoking update_dl_entity() only in case of
wakeup, or if this is a new SCHED_DEADLINE task.
Signed-off-by: NLuca Abeni <luca.abeni@unitn.it>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NJuri Lelli <juri.lelli@gmail.com>
Cc: <stable@vger.kernel.org>
Cc: Dario Faggioli <raistlin@linux.it>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1418813432-20797-2-git-send-email-luca.abeni@unitn.itSigned-off-by: NIngo Molnar <mingo@kernel.org>
      6a503c3b
    • Y
      sched: Fix odd values in effective_load() calculations · 32a8df4e
      由 Yuyang Du 提交于 
      In effective_load, we have (long w * unsigned long tg->shares) / long W,
when w is negative, it is cast to unsigned long and hence the product is
insanely large. Fix this by casting tg->shares to long.
Reported-by: NSasha Levin <sasha.levin@oracle.com>
Signed-off-by: NYuyang Du <yuyang.du@intel.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20141219002956.GA25405@intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      32a8df4e
  11. 23 12月, 2014 1 次提交
  13. 11 12月, 2014 1 次提交
  15. 08 12月, 2014 1 次提交
  17. 04 12月, 2014 1 次提交
  19. 24 11月, 2014 1 次提交
    • T
      sched: Provide update_curr callbacks for stop/idle scheduling classes · 90e362f4
      由 Thomas Gleixner 提交于 
      Chris bisected a NULL pointer deference in task_sched_runtime() to
commit 6e998916 'sched/cputime: Fix clock_nanosleep()/clock_gettime()
inconsistency'.

Chris observed crashes in atop or other /proc walking programs when he
started fork bombs on his machine.  He assumed that this is a new exit
race, but that does not make any sense when looking at that commit.

What's interesting is that, the commit provides update_curr callbacks
for all scheduling classes except stop_task and idle_task.

While nothing can ever hit that via the clock_nanosleep() and
clock_gettime() interfaces, which have been the target of the commit in
question, the author obviously forgot that there are other code paths
which invoke task_sched_runtime()

do_task_stat(()
 thread_group_cputime_adjusted()
   thread_group_cputime()
     task_cputime()
       task_sched_runtime()
        if (task_current(rq, p) && task_on_rq_queued(p)) {
          update_rq_clock(rq);
          up->sched_class->update_curr(rq);
        }

If the stats are read for a stomp machine task, aka 'migration/N' and
that task is current on its cpu, this will happily call the NULL pointer
of stop_task->update_curr.  Ooops.

Chris observation that this happens faster when he runs the fork bomb
makes sense as the fork bomb will kick migration threads more often so
the probability to hit the issue will increase.

Add the missing update_curr callbacks to the scheduler classes stop_task
and idle_task.  While idle tasks cannot be monitored via /proc we have
other means to hit the idle case.

Fixes: 6e998916 'sched/cputime: Fix clock_nanosleep()/clock_gettime() inconsistency'
Reported-by: NChris Mason <clm@fb.com>
Reported-and-tested-by: NBorislav Petkov <bp@alien8.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      90e362f4
  21. 16 11月, 2014 10 次提交