Martin Steigerwald - 10.04.18, 20:43: > Tejun Heo - 03.04.18, 00:04: > > Request abortion is performed by overriding deadline to now and > > scheduling timeout handling immediately. For the latter part, the > > code was using mod_timer(timeout, 0) which can't guarantee that the > > timer runs afterwards. Let's schedule the underlying work item > > directly instead. > > > > This fixes the hangs during probing reported by Sitsofe but it isn't > > yet clear to me how the failure can happen reliably if it's just the > > above described race condition. > > Compiling a 4.16.1 kernel with that patch to test whether this fixes > the boot hang I reported in: > > [Possible REGRESSION, 4.16-rc4] Error updating SMART data during > runtime and boot failures with blk_mq_terminate_expired in backtrace > https://bugzilla.kernel.org/show_bug.cgi?id=199077 Fails as well, see https://bugzilla.kernel.org/show_bug.cgi?id=199077#c8 for photo with (part of) backtrace. > The "Error updating SMART data during runtime" thing I reported there > as well may still be another (independent) issue. > > > Signed-off-by: Tejun Heo <tj@xxxxxxxxxx> > > Reported-by: Sitsofe Wheeler <sitsofe@xxxxxxxxx> > > Reported-by: Meelis Roos <mroos@xxxxxxxx> > > Fixes: 358f70da49d7 ("blk-mq: make blk_abort_request() trigger > > timeout path") Cc: stable@xxxxxxxxxxxxxxx # v4.16 > > Link: > > http://lkml.kernel.org/r/CALjAwxh-PVYFnYFCJpGOja+m5SzZ8Sa4J7ohxdK=r8 > > NyOF-EM A@xxxxxxxxxxxxxx Link: > > http://lkml.kernel.org/r/alpine.LRH.2.21.1802261049140.4893@xxxxxxx. > > ee --- Hello, > > > > I don't have the full explanation yet but here's a preliminary > > patch. > > > > Thanks. > > > > block/blk-timeout.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/block/blk-timeout.c b/block/blk-timeout.c > > index a05e367..f0e6e41 100644 > > --- a/block/blk-timeout.c > > +++ b/block/blk-timeout.c > > @@ -165,7 +165,7 @@ void blk_abort_request(struct request *req) > > > > * No need for fancy synchronizations. > > */ > > > > blk_rq_set_deadline(req, jiffies); > > > > - mod_timer(&req->q->timeout, 0); > > + kblockd_schedule_work(&req->q->timeout_work); > > > > } else { > > > > if (blk_mark_rq_complete(req)) > > > > return; -- Martin
