diff options
| author | Amit Arora <amitarora@in.ibm.com> | 2010-05-19 14:35:57 +0530 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-09-20 13:17:45 -0700 |
| commit | 6f6198a78a34e3d8623f717d05087267e8dedef2 (patch) | |
| tree | 55f1fba919d902bf84c540f6281182dc35a68339 /kernel/sched.c | |
| parent | bd614669ff84a58b5605e7a3c27372ecbf9ff3d1 (diff) | |
sched: kill migration thread in CPU_POST_DEAD instead of CPU_DEAD
[Fixed in a different manner upstream, due to rewrites in this area]
Problem : In a stress test where some heavy tests were running along with
regular CPU offlining and onlining, a hang was observed. The system seems to
be hung at a point where migration_call() tries to kill the migration_thread
of the dying CPU, which just got moved to the current CPU. This migration
thread does not get a chance to run (and die) since rt_throttled is set to 1
on current, and it doesn't get cleared as the hrtimer which is supposed to
reset the rt bandwidth (sched_rt_period_timer) is tied to the CPU which we just
marked dead!
Solution : This patch pushes the killing of migration thread to "CPU_POST_DEAD"
event. By then all the timers (including sched_rt_period_timer) should have got
migrated (along with other callbacks).
Signed-off-by: Amit Arora <amitarora@in.ibm.com>
Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'kernel/sched.c')
| -rw-r--r-- | kernel/sched.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 9990074169f..ba2d610f452 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -7752,14 +7752,24 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu) cpu_rq(cpu)->migration_thread = NULL; break; + case CPU_POST_DEAD: + /* + * Bring the migration thread down in CPU_POST_DEAD event, + * since the timers should have got migrated by now and thus + * we should not see a deadlock between trying to kill the + * migration thread and the sched_rt_period_timer. + */ + rq = cpu_rq(cpu); + kthread_stop(rq->migration_thread); + put_task_struct(rq->migration_thread); + rq->migration_thread = NULL; + break; + case CPU_DEAD: case CPU_DEAD_FROZEN: cpuset_lock(); /* around calls to cpuset_cpus_allowed_lock() */ migrate_live_tasks(cpu); rq = cpu_rq(cpu); - kthread_stop(rq->migration_thread); - put_task_struct(rq->migration_thread); - rq->migration_thread = NULL; /* Idle task back to normal (off runqueue, low prio) */ spin_lock_irq(&rq->lock); update_rq_clock(rq); |