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Thu, 12 Apr 2018 14:12:39 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:51409 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752934AbeDLSMh (ORCPT ); Thu, 12 Apr 2018 14:12:37 -0400 X-Google-Smtp-Source: AIpwx48TuaJGKpgvRFaWijoSxnC/4TjUp6ib0U7r7aVm2k2R0VL8uiB1iiRusSlaXgIJGo5NlWycNQ== From: Alan Jenkins To: Jens Axboe , linux-block@vger.kernel.org Cc: Bart Van Assche , linux-kernel@vger.kernel.org, Alan Jenkins , stable@vger.kernel.org Subject: [PATCH v2] block: do not use interruptible wait anywhere Date: Thu, 12 Apr 2018 19:11:58 +0100 Message-Id: <20180412181158.8884-1-alan.christopher.jenkins@gmail.com> X-Mailer: git-send-email 2.14.3 In-Reply-To: <13e67e1243ebd96f3f56a150d47444ada47ebde0.camel@wdc.com> References: <13e67e1243ebd96f3f56a150d47444ada47ebde0.camel@wdc.com> Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: When blk_queue_enter() waits for a queue to unfreeze, or unset the PREEMPT_ONLY flag, do not allow it to be interrupted by a signal. The PREEMPT_ONLY flag was introduced later in commit 3a0a529971ec ("block, scsi: Make SCSI quiesce and resume work reliably"). Note the SCSI device is resumed asynchronously, i.e. after un-freezing userspace tasks. So that commit exposed the bug as a regression in v4.15. A mysterious SIGBUS (or -EIO) sometimes happened during the time the device was being resumed. Most frequently, there was no kernel log message, and we saw Xorg or Xwayland killed by SIGBUS.[1] [1] E.g. https://bugzilla.redhat.com/show_bug.cgi?id=1553979 Without this fix, I get an IO error in this test: # dd if=/dev/sda of=/dev/null iflag=direct & \ while killall -SIGUSR1 dd; do sleep 0.1; done & \ echo mem > /sys/power/state ; \ sleep 5; killall dd # stop after 5 seconds The interruptible wait was added to blk_queue_enter in commit 3ef28e83ab15 ("block: generic request_queue reference counting"). Before then, the interruptible wait was only in blk-mq, but I don't think it could ever have been correct. Reviewed-by: Bart Van Assche Cc: stable@vger.kernel.org Signed-off-by: Alan Jenkins --- v2: fix indentation block/blk-core.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index abcb8684ba67..1a762f3980f2 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -915,7 +915,6 @@ int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) while (true) { bool success = false; - int ret; rcu_read_lock(); if (percpu_ref_tryget_live(&q->q_usage_counter)) { @@ -947,14 +946,12 @@ int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) */ smp_rmb(); - ret = wait_event_interruptible(q->mq_freeze_wq, - (atomic_read(&q->mq_freeze_depth) == 0 && - (preempt || !blk_queue_preempt_only(q))) || - blk_queue_dying(q)); + wait_event(q->mq_freeze_wq, + (atomic_read(&q->mq_freeze_depth) == 0 && + (preempt || !blk_queue_preempt_only(q))) || + blk_queue_dying(q)); if (blk_queue_dying(q)) return -ENODEV; - if (ret) - return ret; } } -- 2.14.3