On Wed, Oct 26 2016 at 6:54pm -0400, Bart Van Assche <bart.vanassche@xxxxxxxxxxx> wrote: > 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@xxxxxxxxxxx> > Reviewed-by: Hannes Reinecke <hare@xxxxxxxx> > Reviewed-by: Johannes Thumshirn <jthumshirn@xxxxxxx> > Reviewed-by: Christoph Hellwig <hch@xxxxxx> > Cc: Mike Snitzer <snitzer@xxxxxxxxxx> Acked-by: Mike Snitzer <snitzer@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
