Re: BUG: soft lockup - CPU#1 stuck for 1024s!

From: John Stultz
Date: Tue Sep 11 2012 - 19:51:22 EST


On 09/11/2012 04:41 PM, Fengguang Wu wrote:
On Mon, Sep 10, 2012 at 10:06:33AM -0700, John Stultz wrote:
On 09/09/2012 12:59 AM, Fengguang Wu wrote:
Hi John,

The below lockup warning pops up very occasionally in kvm guest
kernels and it's bisected down to

commit 2a8c0883c3cfffcc148ea606e2a4e7453cd75e73
Author: John Stultz <john.stultz@xxxxxxxxxx>
Date: Fri Jul 13 01:21:56 2012 -0400

time: Move xtime_nsec adjustment underflow handling timekeeping_adjust

[ 8.340327] Freeing unused kernel memory: 460k freed
[ 1107.515496] [sched_delayed] sched: RT throttling activated
[ 1107.516439] BUG: soft lockup - CPU#1 stuck for 1024s! [swapper/1:0]

Thanks so much for sending this. One detail I'm curious about is
that these kernels from the Bug messages seem to be v3.6-rc1 or
earlier.

Ingo had a fix 1d17d17484d40f2d5b35c79518597a2b25296996 ("time: Fix
adjustment cleanup bug in timekeeping_adjust") that landed in
3.6-rc2

Has this issue actually been seen on a 3.6-rc2+ kernel?
Nope. I tested -rc5 for 10000+ boots and it's obviously free from the bug.
Sorry for the noise!

No worries. Thanks so much for following up on this, and your continued testing!
-john

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