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 -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
