| From 5b7a12aafedc04b545d0412b5c7e19ab6a10341d Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Sat, 20 Dec 2025 20:03:50 +0800 |
| Subject: dm: remove fake timeout to avoid leak request |
| |
| From: Ding Hui <dinghui@sangfor.com.cn> |
| |
| [ Upstream commit f3a9c95a15d2f4466acad5c68faeff79ca5e9f47 ] |
| |
| Since commit 15f73f5b3e59 ("blk-mq: move failure injection out of |
| blk_mq_complete_request"), drivers are responsible for calling |
| blk_should_fake_timeout() at appropriate code paths and opportunities. |
| |
| However, the dm driver does not implement its own timeout handler and |
| relies on the timeout handling of its slave devices. |
| |
| If an io-timeout-fail error is injected to a dm device, the request |
| will be leaked and never completed, causing tasks to hang indefinitely. |
| |
| Reproduce: |
| 1. prepare dm which has iscsi slave device |
| 2. inject io-timeout-fail to dm |
| echo 1 >/sys/class/block/dm-0/io-timeout-fail |
| echo 100 >/sys/kernel/debug/fail_io_timeout/probability |
| echo 10 >/sys/kernel/debug/fail_io_timeout/times |
| 3. read/write dm |
| 4. iscsiadm -m node -u |
| |
| Result: hang task like below |
| [ 862.243768] INFO: task kworker/u514:2:151 blocked for more than 122 seconds. |
| [ 862.244133] Tainted: G E 6.19.0-rc1+ #51 |
| [ 862.244337] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. |
| [ 862.244718] task:kworker/u514:2 state:D stack:0 pid:151 tgid:151 ppid:2 task_flags:0x4288060 flags:0x00080000 |
| [ 862.245024] Workqueue: iscsi_ctrl_3:1 __iscsi_unbind_session [scsi_transport_iscsi] |
| [ 862.245264] Call Trace: |
| [ 862.245587] <TASK> |
| [ 862.245814] __schedule+0x810/0x15c0 |
| [ 862.246557] schedule+0x69/0x180 |
| [ 862.246760] blk_mq_freeze_queue_wait+0xde/0x120 |
| [ 862.247688] elevator_change+0x16d/0x460 |
| [ 862.247893] elevator_set_none+0x87/0xf0 |
| [ 862.248798] blk_unregister_queue+0x12e/0x2a0 |
| [ 862.248995] __del_gendisk+0x231/0x7e0 |
| [ 862.250143] del_gendisk+0x12f/0x1d0 |
| [ 862.250339] sd_remove+0x85/0x130 [sd_mod] |
| [ 862.250650] device_release_driver_internal+0x36d/0x530 |
| [ 862.250849] bus_remove_device+0x1dd/0x3f0 |
| [ 862.251042] device_del+0x38a/0x930 |
| [ 862.252095] __scsi_remove_device+0x293/0x360 |
| [ 862.252291] scsi_remove_target+0x486/0x760 |
| [ 862.252654] __iscsi_unbind_session+0x18a/0x3e0 [scsi_transport_iscsi] |
| [ 862.252886] process_one_work+0x633/0xe50 |
| [ 862.253101] worker_thread+0x6df/0xf10 |
| [ 862.253647] kthread+0x36d/0x720 |
| [ 862.254533] ret_from_fork+0x2a6/0x470 |
| [ 862.255852] ret_from_fork_asm+0x1a/0x30 |
| [ 862.256037] </TASK> |
| |
| Remove the blk_should_fake_timeout() check from dm, as dm has no |
| native timeout handling and should not attempt to fake timeouts. |
| |
| Signed-off-by: Ding Hui <dinghui@sangfor.com.cn> |
| Reviewed-by: Christoph Hellwig <hch@lst.de> |
| Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/md/dm-rq.c | 3 +-- |
| 1 file changed, 1 insertion(+), 2 deletions(-) |
| |
| diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c |
| index a6ea77432e34c..29a09452abc4a 100644 |
| --- a/drivers/md/dm-rq.c |
| +++ b/drivers/md/dm-rq.c |
| @@ -281,8 +281,7 @@ static void dm_complete_request(struct request *rq, blk_status_t error) |
| struct dm_rq_target_io *tio = tio_from_request(rq); |
| |
| tio->error = error; |
| - if (likely(!blk_should_fake_timeout(rq->q))) |
| - blk_mq_complete_request(rq); |
| + blk_mq_complete_request(rq); |
| } |
| |
| /* |
| -- |
| 2.51.0 |
| |
