This is a note to let you know that I've just added the patch titled
tick: Cleanup NOHZ per cpu data on cpu down
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tick-cleanup-nohz-per-cpu-data-on-cpu-down.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4b0c0f294f60abcdd20994a8341a95c8ac5eeb96 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Fri, 3 May 2013 15:02:50 +0200
Subject: tick: Cleanup NOHZ per cpu data on cpu down
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
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 <prarit@xxxxxxxxxx>
Cc: Mike Galbraith <bitbucket@xxxxxxxxx>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1305031451561.2886@ionos
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/time/tick-sched.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- 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
Patches currently in stable-queue which might be from tglx@xxxxxxxxxxxxx are
queue-3.4/tick-cleanup-nohz-per-cpu-data-on-cpu-down.patch
queue-3.4/timer-don-t-reinitialize-the-cpu-base-lock-during-cpu_up_prepare.patch
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