From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Sender: Tejun Heo Date: Mon, 2 Apr 2018 15:04:58 -0700 From: Tejun Heo To: Sitsofe Wheeler Cc: Jens Axboe , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, Stefan Haberland , Jan Hoeppner , Bart Van Assche Subject: [PATCH] blk-mq: Directly schedule q->timeout_work when aborting a request Message-ID: <20180402220458.GJ388343@devbig577.frc2.facebook.com> References: <20180402202951.GE388343@devbig577.frc2.facebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: List-ID: 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. Signed-off-by: Tejun Heo Reported-by: Sitsofe Wheeler Reported-by: Meelis Roos Fixes: 358f70da49d7 ("blk-mq: make blk_abort_request() trigger timeout path") Cc: stable@vger.kernel.org # v4.16 Link: http://lkml.kernel.org/r/CALjAwxh-PVYFnYFCJpGOja+m5SzZ8Sa4J7ohxdK=r8NyOF-EMA@mail.gmail.com Link: http://lkml.kernel.org/r/alpine.LRH.2.21.1802261049140.4893@math.ut.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;