From 75d91423f4af9c351d2d5541fe96e3ba53d07d17 Mon Sep 17 00:00:00 2001 From: Alan Jenkins Date: Thu, 12 Apr 2018 19:11:58 +0100 Subject: [PATCH] block: do not use interruptible wait anywhere 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: 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 Signed-off-by: Jens Axboe (cherry picked from commit 1dc3039bc87ae7d19a990c3ee71cfd8a9068f428) Orabug: 29674055 Signed-off-by: Junxiao Bi Reviewed-by: Wengang Wang Conflicts: block/blk-core.c Signed-off-by: Brian Maly --- block/blk-core.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 4f2617488ffa..3c92b0973854 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -612,21 +612,17 @@ EXPORT_SYMBOL(blk_alloc_queue); int blk_queue_enter(struct request_queue *q, gfp_t gfp) { while (true) { - int ret; - if (percpu_ref_tryget_live(&q->q_usage_counter)) return 0; if (!(gfp & __GFP_WAIT)) return -EBUSY; - ret = wait_event_interruptible(q->mq_freeze_wq, + wait_event(q->mq_freeze_wq, !atomic_read(&q->mq_freeze_depth) || blk_queue_dying(q)); if (blk_queue_dying(q)) return -ENODEV; - if (ret) - return ret; } } -- 2.50.1