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tick: Cleanup NOHZ per cpu data on cpu down

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commit 4b0c0f294f upstream.

Prarit reported a crash on CPU offline/online. The reason is that on
CPU down the NOHZ related per cpu data of the dead cpu is not cleaned
up. If at cpu online an interrupt happens before the per cpu tick
device is registered the irq_enter() check potentially sees stale data
and dereferences a NULL pointer.

Cleanup the data after the cpu is dead.

Reported-by: Prarit Bhargava <prarit@redhat.com>
Cc: Mike Galbraith <bitbucket@online.de>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1305031451561.2886@ionos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Thomas Gleixner 2013-05-03 15:02:50 +02:00 committed by Greg Kroah-Hartman
parent ed032fd4d8
commit 33b7cfcb34
1 changed files with 1 additions and 1 deletions
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2
kernel/time/tick-sched.c
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@ -866,7 +866,7 @@ void tick_cancel_sched_timer(int cpu)
hrtimer_cancel(&ts->sched_timer);
# endif
ts->nohz_mode = NOHZ_MODE_INACTIVE;
memset(ts, 0, sizeof(*ts));
}
#endif