Commit 4b0c0f29 authored May 03, 2013 by Thomas Gleixner

tick: Cleanup NOHZ per cpu data on cpu down



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: stable@vger.kernel.org
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>

parent fbd44a60

kernel/time/tick-sched.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -904,7 +904,7 @@ void tick_cancel_sched_timer(int cpu)
	hrtimer_cancel(&ts->sched_timer);		hrtimer_cancel(&ts->sched_timer);
	# endif		# endif

	ts->nohz_mode = NOHZ_MODE_INACTIVE;		memset(ts, 0, sizeof(*ts));
	}		}
	#endif		#endif

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