Re: frequent lockups in 3.18rc4

From: Mike Galbraith
Date: Tue Dec 02 2014 - 09:13:35 EST


On Mon, 2014-12-01 at 18:08 -0500, Chris Mason wrote:
> I'm not sure if this is related, but running trinity here, I noticed it
> was stuck at 100% system time on every CPU. perf report tells me we are
> spending all of our time in spin_lock under the sync system call.
>
> I think it's coming from contention in the bdi_queue_work() call from
> inside sync_inodes_sb, which is spin_lock_bh().
>
> I wonder if we're just spinning so hard on this one bh lock that we're
> starving the watchdog?

The bean counting problem below can contribute.

https://lkml.org/lkml/2014/3/30/7

-Mike

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