Re: Call trace in ext4_es_lru_add on 3.10 stable

[Jan Kara <jack@suse.cz>]

On Tue 23-09-14 14:23:29, Stefan Priebe wrote:
> 
> Am 23.09.2014 11:42, schrieb Jan Kara:
> >On Tue 23-09-14 09:50:25, Stefan Priebe - Profihost AG wrote:
> >>
> >>Am 22.09.2014 um 22:20 schrieb Theodore Ts'o:
> >>>On Mon, Sep 22, 2014 at 08:29:54PM +0200, Stefan Priebe wrote:
> >>>>Hi,
> >>>>Am 22.09.2014 18:47, schrieb Theodore Ts'o:
> >>>>>On Mon, Sep 22, 2014 at 08:56:23AM +0200, Stefan Priebe wrote:
> >>>>>>>That's not the whole message; you just weren't able to capture it all.
> >>>>>>>How are you capturing these messages, by the way?  Serial console?
> >>>>>>
> >>>>>>Sorry this was an incomplete copy and paste by me.
> >>>>>>
> >>>>>>Here is the complete output:
> >>>>>>[1578544.839610] BUG: soft lockup - CPU#7 stuck for 22s! [mysqld:29281]
> >>>>>>[1578544.893450] Modules linked in: nf_conntrack_ipv4 nf_defrag_ipv4
> >>>>>
> >>>>>OK, thanks, this is a known bug, where when ext4 is under heavy memory
> >>>>>pressure, we can end up stalling in reclaim.  This message indicates
> >>>>>that the system got stalled for 22 seconds, which is not good, since
> >>>>>it impacts the interactivity of your system, and increases the
> >>>>>long-tail latency of requests to servers running on your system, but
> >>>>>it doesn't cause any data loss or will cause any of your processes to
> >>>>>crash or otherwise stop functioning (except for temporarily).
> >>>>>
> >>>>>It's something that we are working on, and there are patches which
> >>>>>Zheng Liu submitted that still need a bit of polishing, but I hope to
> >>>>>have it addressed soon.
> >>>>
> >>>>Thanks for your feedback. Will those patches go to stable? Any link to
> >>>>those patches?
> >>>
> >>>I'm not sure they will go to Stable when they are ready, because the
> >>>patches are somewhat complex and so they may not apply cleanly to much
> >>>older kernels.
> >>>
> >>>The patches under discussion (some have been applied, others hae been
> >>>waiting for some requested changes) can be found here:
> >>>
> >>>http://patchwork.ozlabs.org/patch/377720
> >>>http://patchwork.ozlabs.org/patch/377721
> >>>http://patchwork.ozlabs.org/patch/377722
> >>>http://patchwork.ozlabs.org/patch/377723
> >>>http://patchwork.ozlabs.org/patch/377724
> >>>http://patchwork.ozlabs.org/patch/377725
> >>>http://patchwork.ozlabs.org/patch/377727
> >>
> >>hui that's a lot. Are they ALL needed to fix this?
> >   Yes, all of them are needed.
> 
> How can i get notified when they're ready / polished?
  Watching changes to fs/ext4/extents_status.c is probably the most
reliable. Or maybe Zheng (Cced) can add you to CC list when submitting the
patch set next time.

								Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR