* [PATCH] dm: remove fake timeout to avoid leak request
@ 2025-12-20 12:03 Ding Hui
2025-12-22 22:21 ` Christoph Hellwig
2026-01-12 6:43 ` Ding Hui
0 siblings, 2 replies; 4+ messages in thread
From: Ding Hui @ 2025-12-20 12:03 UTC (permalink / raw)
To: linux-kernel, dm-devel; +Cc: bmarzins, mpatocka, snitzer, agk, hch, Ding Hui
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>
---
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 a6ca92049c10..5e0854669614 100644
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -278,8 +278,7 @@ 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);
}
/*
--
2.17.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] dm: remove fake timeout to avoid leak request
2025-12-20 12:03 [PATCH] dm: remove fake timeout to avoid leak request Ding Hui
@ 2025-12-22 22:21 ` Christoph Hellwig
2026-01-12 6:43 ` Ding Hui
1 sibling, 0 replies; 4+ messages in thread
From: Christoph Hellwig @ 2025-12-22 22:21 UTC (permalink / raw)
To: Ding Hui; +Cc: linux-kernel, dm-devel, bmarzins, mpatocka, snitzer, agk, hch
Looks good:
Reviewed-by: Christoph Hellwig <hch@lst.de>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] dm: remove fake timeout to avoid leak request
2025-12-20 12:03 [PATCH] dm: remove fake timeout to avoid leak request Ding Hui
2025-12-22 22:21 ` Christoph Hellwig
@ 2026-01-12 6:43 ` Ding Hui
2026-01-12 17:27 ` Mikulas Patocka
1 sibling, 1 reply; 4+ messages in thread
From: Ding Hui @ 2026-01-12 6:43 UTC (permalink / raw)
To: agk, snitzer, mpatocka, bmarzins; +Cc: hch, dm-devel, linux-kernel
Hi,
Sorry for this ping mail as there is no feedback from maintainers, just in
case the patch was forgotten somewhere.
And it has already received a Reviewed-by from Christoph last month.
On 2025/12/20 20:03, Ding Hui wrote:
> 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>
> ---
> 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 a6ca92049c10..5e0854669614 100644
> --- a/drivers/md/dm-rq.c
> +++ b/drivers/md/dm-rq.c
> @@ -278,8 +278,7 @@ 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);
> }
>
> /*
--
Thanks,
- Ding Hui
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] dm: remove fake timeout to avoid leak request
2026-01-12 6:43 ` Ding Hui
@ 2026-01-12 17:27 ` Mikulas Patocka
0 siblings, 0 replies; 4+ messages in thread
From: Mikulas Patocka @ 2026-01-12 17:27 UTC (permalink / raw)
To: Ding Hui; +Cc: agk, snitzer, bmarzins, hch, dm-devel, linux-kernel
On Mon, 12 Jan 2026, Ding Hui wrote:
> Hi,
>
> Sorry for this ping mail as there is no feedback from maintainers, just in
> case the patch was forgotten somewhere.
>
> And it has already received a Reviewed-by from Christoph last month.
Hi
I committed the patch - it is in the linux-dm git, branch for-next.
Mikulas
> On 2025/12/20 20:03, Ding Hui wrote:
> > 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>
> > ---
> > 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 a6ca92049c10..5e0854669614 100644
> > --- a/drivers/md/dm-rq.c
> > +++ b/drivers/md/dm-rq.c
> > @@ -278,8 +278,7 @@ 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);
> > }
> > /*
>
> --
> Thanks,
> - Ding Hui
>
^ permalink raw reply [flat|nested] 4+ messages in thread
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2025-12-20 12:03 [PATCH] dm: remove fake timeout to avoid leak request Ding Hui
2025-12-22 22:21 ` Christoph Hellwig
2026-01-12 6:43 ` Ding Hui
2026-01-12 17:27 ` Mikulas Patocka
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