On Fri, Jun 27 2014 at 9:33am -0400, Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > On Fri, Jun 27 2014 at 9:02am -0400, > Bart Van Assche <bvanassche@xxxxxxx> wrote: > > > Hello, > > > > While running a cable pull simulation test with dm_multipath on top of > > the SRP initiator driver I noticed that after a few iterations I/O locks > > up instead of dm_multipath processing the path failure properly (see also > > below for a call trace). At least kernel versions 3.15 and 3.16-rc2 are > > vulnerable. This issue does not occur with kernel 3.14. I have tried to > > bisect this but gave up when I noticed that I/O locked up completely with > > a kernel built from git commit ID e809917735ebf1b9a56c24e877ce0d320baee2ec > > (dm mpath: push back requests instead of queueing). But with the bisect I > > have been able to narrow down this issue to one of the patches in "Merge > > tag 'dm-3.15-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/ > > device-mapper/linux-dm". Does anyone have a suggestion how to analyze this > > further or how to fix this ? I still don't have a _known_ fix for your issue but I reviewed commit e809917735ebf1b9a56c24e877ce0d320baee2ec closer and identified what looks to be a regression in logic for multipath_busy, it now calls !pg_ready() instead of directly checking pg_init_in_progress. I think this is needed (Hannes, what do you think?): diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index 3f6fd9d..561ead6 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -373,7 +373,7 @@ static int __must_push_back(struct multipath *m) dm_noflush_suspending(m->ti))); } -#define pg_ready(m) (!(m)->queue_io && !(m)->pg_init_required) +#define pg_ready(m) (!(m)->queue_io && !(m)->pg_init_required && !(m)->pg_init_in_progress) /* * Map cloned requests -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
