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sched: teach migrate_disable about atomic contexts 

<NMI>  [<ffffffff812dafd8>] spin_bug+0x94/0xa8
 [<ffffffff812db07f>] do_raw_spin_lock+0x43/0xea
 [<ffffffff814fa9be>] _raw_spin_lock_irqsave+0x6b/0x85
 [<ffffffff8106ff9e>] ? migrate_disable+0x75/0x12d
 [<ffffffff81078aaf>] ? pin_current_cpu+0x36/0xb0
 [<ffffffff8106ff9e>] migrate_disable+0x75/0x12d
 [<ffffffff81115b9d>] pagefault_disable+0xe/0x1f
 [<ffffffff81047027>] copy_from_user_nmi+0x74/0xe6
 [<ffffffff810489d7>] perf_callchain_user+0xf3/0x135

Now clearly we can't go around taking locks from NMI context, cure
this by short-circuiting migrate_disable() when we're in an atomic
context already.

Add some extra debugging to avoid things like:

  preempt_disable()
  migrate_disable();

  preempt_enable();
  migrate_enable();

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1314967297.1301.14.camel@twins
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/n/tip-wbot4vsmwhi8vmbf83hsclk6@git.kernel.org
This commit is contained in:
Peter Zijlstra 2011-09-02 14:29:27 +02:00 committed by Alibek Omarov
parent ba96b8da71
commit 9bb1b14870
2 changed files with 24 additions and 0 deletions
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3
include/linux/sched.h
View File

@ -1204,6 +1204,9 @@ struct task_struct {
unsigned int policy;
#ifdef CONFIG_PREEMPT_RT_FULL
int migrate_disable;
# ifdef CONFIG_SCHED_DEBUG
int migrate_disable_atomic;
# endif
#endif
int nr_cpus_allowed;
cpumask_t cpus_allowed;

21
kernel/sched/core.c
View File

@ -4732,6 +4732,17 @@ void migrate_disable(void)
unsigned long flags;
struct rq *rq;
if (in_atomic()) {
#ifdef CONFIG_SCHED_DEBUG
p->migrate_disable_atomic++;
#endif
return;
}
#ifdef CONFIG_SCHED_DEBUG
WARN_ON_ONCE(p->migrate_disable_atomic);
#endif
preempt_disable();
if (p->migrate_disable) {
p->migrate_disable++;
@ -4780,6 +4791,16 @@ void migrate_enable(void)
unsigned long flags;
struct rq *rq;
if (in_atomic()) {
#ifdef CONFIG_SCHED_DEBUG
p->migrate_disable_atomic--;
#endif
return;
}
#ifdef CONFIG_SCHED_DEBUG
WARN_ON_ONCE(p->migrate_disable_atomic);
#endif
WARN_ON_ONCE(p->migrate_disable <= 0);
preempt_disable();