From 33b7cfcb34b4ae37cde7a8a1c97c9be27677e931 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 3 May 2013 15:02:50 +0200 Subject: tick: Cleanup NOHZ per cpu data on cpu down commit 4b0c0f294f60abcdd20994a8341a95c8ac5eeb96 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 Cc: Mike Galbraith Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1305031451561.2886@ionos Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman --- kernel/time/tick-sched.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 01d8e62ac36..6570548d088 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -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 -- cgit v1.2.3-18-g5258