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 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=r8NyOF-EM > A@xxxxxxxxxxxxxx Link: > http://lkml.kernel.org/r/alpine.LRH.2.21.1802261049140.4893@xxxxxxxxxx --- > 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
