diff options
| author | Alan Jenkins <alan.christopher.jenkins@gmail.com> | 2018-04-12 19:11:58 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-07-25 10:18:32 +0200 |
| commit | c9ae49135d83243f12b5a66044302d4a17e0dcfe (patch) | |
| tree | 07cee7f8e3b1b063be3914cba657e3a7917d0d11 | |
| parent | 42a8fe474e0c3e9babad09b4d3e882d7a0f09c76 (diff) | |
block: do not use interruptible wait anywhere
commit 1dc3039bc87ae7d19a990c3ee71cfd8a9068f428 upstream.
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 <bart.vanassche@wdc.com>
Cc: stable@vger.kernel.org
Signed-off-by: Alan Jenkins <alan.christopher.jenkins@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | block/blk-core.c | 10 |
1 files changed, 3 insertions, 7 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index f5f1a55703ae..50d77c90070d 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -651,21 +651,17 @@ 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 (!gfpflags_allow_blocking(gfp)) return -EBUSY; - ret = wait_event_interruptible(q->mq_freeze_wq, - !atomic_read(&q->mq_freeze_depth) || - blk_queue_dying(q)); + 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; } } |