diff options
| author | Bart Van Assche <bart.vanassche@sandisk.com> | 2016-10-29 02:22:16 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2016-11-02 19:50:19 +0100 |
| commit | 7b17c2f7292ba1f3f98dae3f7077f9e569653276 (patch) | |
| tree | 9ecdb84ec0e213577eb5b7fd05b5086811044056 /drivers/md/dm-rq.c | |
| parent | dm: Use BLK_MQ_S_STOPPED instead of QUEUE_FLAG_STOPPED in blk-mq code (diff) | |
| download | linux-7b17c2f7292ba1f3f98dae3f7077f9e569653276.tar.xz linux-7b17c2f7292ba1f3f98dae3f7077f9e569653276.zip | |
dm: Fix a race condition related to stopping and starting queues
Ensure that all ongoing dm_mq_queue_rq() and dm_mq_requeue_request()
calls have stopped before setting the "queue stopped" flag. This
allows to remove the "queue stopped" test from dm_mq_queue_rq() and
dm_mq_requeue_request(). This patch fixes a race condition because
dm_mq_queue_rq() is called without holding the queue lock and hence
BLK_MQ_S_STOPPED can be set at any time while dm_mq_queue_rq() is
in progress. This patch prevents that the following hang occurs
sporadically when using dm-mq:
INFO: task systemd-udevd:10111 blocked for more than 480 seconds.
Call Trace:
[<ffffffff8161f397>] schedule+0x37/0x90
[<ffffffff816239ef>] schedule_timeout+0x27f/0x470
[<ffffffff8161e76f>] io_schedule_timeout+0x9f/0x110
[<ffffffff8161fb36>] bit_wait_io+0x16/0x60
[<ffffffff8161f929>] __wait_on_bit_lock+0x49/0xa0
[<ffffffff8114fe69>] __lock_page+0xb9/0xc0
[<ffffffff81165d90>] truncate_inode_pages_range+0x3e0/0x760
[<ffffffff81166120>] truncate_inode_pages+0x10/0x20
[<ffffffff81212a20>] kill_bdev+0x30/0x40
[<ffffffff81213d41>] __blkdev_put+0x71/0x360
[<ffffffff81214079>] blkdev_put+0x49/0x170
[<ffffffff812141c0>] blkdev_close+0x20/0x30
[<ffffffff811d48e8>] __fput+0xe8/0x1f0
[<ffffffff811d4a29>] ____fput+0x9/0x10
[<ffffffff810842d3>] task_work_run+0x83/0xb0
[<ffffffff8106606e>] do_exit+0x3ee/0xc40
[<ffffffff8106694b>] do_group_exit+0x4b/0xc0
[<ffffffff81073d9a>] get_signal+0x2ca/0x940
[<ffffffff8101bf43>] do_signal+0x23/0x660
[<ffffffff810022b3>] exit_to_usermode_loop+0x73/0xb0
[<ffffffff81002cb0>] syscall_return_slowpath+0xb0/0xc0
[<ffffffff81624e33>] entry_SYSCALL_64_fastpath+0xa6/0xa8
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'drivers/md/dm-rq.c')
| -rw-r--r-- | drivers/md/dm-rq.c | 13 |
1 files changed, 1 insertions, 12 deletions
diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c index 09c958b6f038..8b92e066bb69 100644 --- a/drivers/md/dm-rq.c +++ b/drivers/md/dm-rq.c @@ -102,7 +102,7 @@ static void dm_mq_stop_queue(struct request_queue *q) if (blk_mq_queue_stopped(q)) return; - blk_mq_stop_hw_queues(q); + blk_mq_quiesce_queue(q); } void dm_stop_queue(struct request_queue *q) @@ -880,17 +880,6 @@ static int dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx, dm_put_live_table(md, srcu_idx); } - /* - * On suspend dm_stop_queue() handles stopping the blk-mq - * request_queue BUT: even though the hw_queues are marked - * BLK_MQ_S_STOPPED at that point there is still a race that - * is allowing block/blk-mq.c to call ->queue_rq against a - * hctx that it really shouldn't. The following check guards - * against this rarity (albeit _not_ race-free). - */ - if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state))) - return BLK_MQ_RQ_QUEUE_BUSY; - if (ti->type->busy && ti->type->busy(ti)) return BLK_MQ_RQ_QUEUE_BUSY; |