Messages in this thread | | | Date | Wed, 09 Aug 2017 06:28:37 +0000 | From | David R <> | Subject | Re: [MD] Crash with 4.12+ kernel and high disk load -- bisected to 4ad23a976413: MD: use per-cpu counter for writes_pending |
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My raid check also ran through cleanly, so feel free to add my Tested-By:
Cheers David
Quoting Dominik Brodowski <linux@dominikbrodowski.net>:
> 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@suse.com> >> > > 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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