My raid check also ran through cleanly, so feel free to add my Tested-By:
Cheers
David
Quoting Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>:
On Tue, Aug 08, 2017 at 09:36:14AM +0200, Dominik Brodowski wrote:
On Tue, Aug 08, 2017 at 05:01:28PM +1000, NeilBrown wrote:
> On Mon, Aug 07 2017, Dominik Brodowski wrote:
>
> > Neil, Shaohua,
> >
> > following up on David R's bug message: I have observed something similar
> > on v4.12.[345] and v4.13-rc4, but not on v4.11. This is a RAID1 (on bare
> > metal partitions, /dev/sdaX and /dev/sdbY linked together). In case it
> > matters: Further upwards are cryptsetup, a DM volume group, then logical
> > volumes, and then filesystems (ext4, but also happened with xfs).
> >
> > In a tedious bisect (the bug wasn't as quickly reproducible as
I would like,
> > but happened when I repeatedly created large lvs and filled
them with some
> > content, while compiling kernels in parallel), I was able to track this
> > down to:
> >
> >
> > commit 4ad23a976413aa57fe5ba7a25953dc35ccca5b71
> > Author: NeilBrown <neilb@xxxxxxxx>
> > Date: Wed Mar 15 14:05:14 2017 +1100
> >
> > MD: use per-cpu counter for writes_pending
> >
> > The 'writes_pending' counter is used to determine when the
> > array is stable so that it can be marked in the superblock
> > as "Clean". Consequently it needs to be updated frequently
> > but only checked for zero occasionally. Recent changes to
> > raid5 cause the count to be updated even more often - once
> > per 4K rather than once per bio. This provided
> > justification for making the updates more efficient.
> >
> > ...
>
> Thanks for the report... and for bisecting and for re-sending...
>
> I believe I have found the problem, and have sent a patch separately.
>
> If mddev->safemode == 1 and mddev->in_sync != 0, md_check_recovery()
> causes the thread that calls it to spin.
> Prior to the patch you found, that couldn't happen. Now it can,
> so it needs to be handled more carefully.
>
> While I was examining the code, I found another bug - so that is a win!
>
> Thanks,
> NeilBrown
Nice catch. Thanks! Will give it (both patches at once) a try on the test
system immediately.
More than 2 hours of stress-testing shows no issues any more. Very nice.
Thanks!
Dominik
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