| Message ID | c183dd5c-da91-c71-dccc-c923977bc77@redhat.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Delegated to: | Mike Snitzer |
| Headers | show |
| Series | dm-io: don't warn if flush takes too long time | expand |
On 4/12/24 21:46, Mikulas Patocka wrote: > There was reported hang warning when using dm-integrity on the top of loop > device on XFS on a rotational disk. The warning was triggered because > flush on the loop device was too slow. > > There's no easy way to reduce the latency, so I made a patch that shuts > the warning up. > > There's already a function blk_wait_io that avoids the hung task warning. > This commit moves this function from block/blk.h to > include/linux/completion.h and uses it in dm-io instead of > wait_for_completion_io. > > [ 1352.586981] INFO: task kworker/1:2:14820 blocked for more than 120 seconds. > [ 1352.593951] Not tainted 4.18.0-552.el8_10.x86_64 #1 > [ 1352.599358] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > [ 1352.607202] Call Trace: > [ 1352.609670] __schedule+0x2d1/0x870 > [ 1352.613173] ? update_load_avg+0x7e/0x710 > [ 1352.617193] ? update_load_avg+0x7e/0x710 > [ 1352.621214] schedule+0x55/0xf0 > [ 1352.624371] schedule_timeout+0x281/0x320 > [ 1352.628393] ? __schedule+0x2d9/0x870 > [ 1352.632065] io_schedule_timeout+0x19/0x40 > [ 1352.636176] wait_for_completion_io+0x96/0x100 > [ 1352.640639] sync_io+0xcc/0x120 [dm_mod] > [ 1352.644592] dm_io+0x209/0x230 [dm_mod] > [ 1352.648436] ? bit_wait_timeout+0xa0/0xa0 > [ 1352.652461] ? vm_next_page+0x20/0x20 [dm_mod] > [ 1352.656924] ? km_get_page+0x60/0x60 [dm_mod] > [ 1352.661298] dm_bufio_issue_flush+0xa0/0xd0 [dm_bufio] > [ 1352.666448] dm_bufio_write_dirty_buffers+0x1a0/0x1e0 [dm_bufio] > [ 1352.672462] dm_integrity_flush_buffers+0x32/0x140 [dm_integrity] > [ 1352.678567] ? lock_timer_base+0x67/0x90 > [ 1352.682505] ? __timer_delete.part.36+0x5c/0x90 > [ 1352.687050] integrity_commit+0x31a/0x330 [dm_integrity] > [ 1352.692368] ? __switch_to+0x10c/0x430 > [ 1352.696131] process_one_work+0x1d3/0x390 > [ 1352.700152] ? process_one_work+0x390/0x390 > [ 1352.704348] worker_thread+0x30/0x390 > [ 1352.708019] ? process_one_work+0x390/0x390 > [ 1352.712214] kthread+0x134/0x150 > [ 1352.715459] ? set_kthread_struct+0x50/0x50 > [ 1352.719659] ret_from_fork+0x1f/0x40 > > Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> > > --- > block/blk.h | 12 ------------ > drivers/md/dm-io.c | 2 +- > include/linux/completion.h | 13 +++++++++++++ > 3 files changed, 14 insertions(+), 13 deletions(-) > > Index: linux-2.6/block/blk.h > =================================================================== > --- linux-2.6.orig/block/blk.h 2024-03-30 20:07:03.000000000 +0100 > +++ linux-2.6/block/blk.h 2024-04-12 12:45:13.000000000 +0200 > @@ -72,18 +72,6 @@ static inline int bio_queue_enter(struct > return __bio_queue_enter(q, bio); > } > > -static inline void blk_wait_io(struct completion *done) > -{ > - /* Prevent hang_check timer from firing at us during very long I/O */ > - unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2; > - > - if (timeout) > - while (!wait_for_completion_io_timeout(done, timeout)) > - ; > - else > - wait_for_completion_io(done); > -} > - > #define BIO_INLINE_VECS 4 > struct bio_vec *bvec_alloc(mempool_t *pool, unsigned short *nr_vecs, > gfp_t gfp_mask); > Index: linux-2.6/drivers/md/dm-io.c > =================================================================== > --- linux-2.6.orig/drivers/md/dm-io.c 2024-03-30 20:07:03.000000000 +0100 > +++ linux-2.6/drivers/md/dm-io.c 2024-04-12 12:42:17.000000000 +0200 > @@ -450,7 +450,7 @@ static int sync_io(struct dm_io_client * > > dispatch_io(opf, num_regions, where, dp, io, 1, ioprio); > > - wait_for_completion_io(&sio.wait); > + blk_wait_io(&sio.wait); > > if (error_bits) > *error_bits = sio.error_bits; > Index: linux-2.6/include/linux/completion.h > =================================================================== > --- linux-2.6.orig/include/linux/completion.h 2023-10-31 15:31:42.000000000 +0100 > +++ linux-2.6/include/linux/completion.h 2024-04-12 12:46:08.000000000 +0200 > @@ -10,6 +10,7 @@ > */ > > #include <linux/swait.h> > +#include <linux/sched/sysctl.h> > > /* > * struct completion - structure used to maintain state for a "completion" > @@ -119,4 +120,16 @@ extern void complete(struct completion * > extern void complete_on_current_cpu(struct completion *x); > extern void complete_all(struct completion *); > > +static inline void blk_wait_io(struct completion *done) Since you move this function outside of the block layer, the "blk_" prefix seems out of place. What about renaming this to something like "wait_for_completion_blk_io()", or to make it clear that it is not the same as wait_for_completion_io(), may be "wait_for_completion_long_io()" ? > +{ > + /* Prevent hang_check timer from firing at us during very long I/O */ > + unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2; > + > + if (timeout) > + while (!wait_for_completion_io_timeout(done, timeout)) > + ; > + else > + wait_for_completion_io(done); > +} > + > #endif > >
Index: linux-2.6/block/blk.h =================================================================== --- linux-2.6.orig/block/blk.h 2024-03-30 20:07:03.000000000 +0100 +++ linux-2.6/block/blk.h 2024-04-12 12:45:13.000000000 +0200 @@ -72,18 +72,6 @@ static inline int bio_queue_enter(struct return __bio_queue_enter(q, bio); } -static inline void blk_wait_io(struct completion *done) -{ - /* Prevent hang_check timer from firing at us during very long I/O */ - unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2; - - if (timeout) - while (!wait_for_completion_io_timeout(done, timeout)) - ; - else - wait_for_completion_io(done); -} - #define BIO_INLINE_VECS 4 struct bio_vec *bvec_alloc(mempool_t *pool, unsigned short *nr_vecs, gfp_t gfp_mask); Index: linux-2.6/drivers/md/dm-io.c =================================================================== --- linux-2.6.orig/drivers/md/dm-io.c 2024-03-30 20:07:03.000000000 +0100 +++ linux-2.6/drivers/md/dm-io.c 2024-04-12 12:42:17.000000000 +0200 @@ -450,7 +450,7 @@ static int sync_io(struct dm_io_client * dispatch_io(opf, num_regions, where, dp, io, 1, ioprio); - wait_for_completion_io(&sio.wait); + blk_wait_io(&sio.wait); if (error_bits) *error_bits = sio.error_bits; Index: linux-2.6/include/linux/completion.h =================================================================== --- linux-2.6.orig/include/linux/completion.h 2023-10-31 15:31:42.000000000 +0100 +++ linux-2.6/include/linux/completion.h 2024-04-12 12:46:08.000000000 +0200 @@ -10,6 +10,7 @@ */ #include <linux/swait.h> +#include <linux/sched/sysctl.h> /* * struct completion - structure used to maintain state for a "completion" @@ -119,4 +120,16 @@ extern void complete(struct completion * extern void complete_on_current_cpu(struct completion *x); extern void complete_all(struct completion *); +static inline void blk_wait_io(struct completion *done) +{ + /* Prevent hang_check timer from firing at us during very long I/O */ + unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2; + + if (timeout) + while (!wait_for_completion_io_timeout(done, timeout)) + ; + else + wait_for_completion_io(done); +} + #endif
There was reported hang warning when using dm-integrity on the top of loop device on XFS on a rotational disk. The warning was triggered because flush on the loop device was too slow. There's no easy way to reduce the latency, so I made a patch that shuts the warning up. There's already a function blk_wait_io that avoids the hung task warning. This commit moves this function from block/blk.h to include/linux/completion.h and uses it in dm-io instead of wait_for_completion_io. [ 1352.586981] INFO: task kworker/1:2:14820 blocked for more than 120 seconds. [ 1352.593951] Not tainted 4.18.0-552.el8_10.x86_64 #1 [ 1352.599358] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1352.607202] Call Trace: [ 1352.609670] __schedule+0x2d1/0x870 [ 1352.613173] ? update_load_avg+0x7e/0x710 [ 1352.617193] ? update_load_avg+0x7e/0x710 [ 1352.621214] schedule+0x55/0xf0 [ 1352.624371] schedule_timeout+0x281/0x320 [ 1352.628393] ? __schedule+0x2d9/0x870 [ 1352.632065] io_schedule_timeout+0x19/0x40 [ 1352.636176] wait_for_completion_io+0x96/0x100 [ 1352.640639] sync_io+0xcc/0x120 [dm_mod] [ 1352.644592] dm_io+0x209/0x230 [dm_mod] [ 1352.648436] ? bit_wait_timeout+0xa0/0xa0 [ 1352.652461] ? vm_next_page+0x20/0x20 [dm_mod] [ 1352.656924] ? km_get_page+0x60/0x60 [dm_mod] [ 1352.661298] dm_bufio_issue_flush+0xa0/0xd0 [dm_bufio] [ 1352.666448] dm_bufio_write_dirty_buffers+0x1a0/0x1e0 [dm_bufio] [ 1352.672462] dm_integrity_flush_buffers+0x32/0x140 [dm_integrity] [ 1352.678567] ? lock_timer_base+0x67/0x90 [ 1352.682505] ? __timer_delete.part.36+0x5c/0x90 [ 1352.687050] integrity_commit+0x31a/0x330 [dm_integrity] [ 1352.692368] ? __switch_to+0x10c/0x430 [ 1352.696131] process_one_work+0x1d3/0x390 [ 1352.700152] ? process_one_work+0x390/0x390 [ 1352.704348] worker_thread+0x30/0x390 [ 1352.708019] ? process_one_work+0x390/0x390 [ 1352.712214] kthread+0x134/0x150 [ 1352.715459] ? set_kthread_struct+0x50/0x50 [ 1352.719659] ret_from_fork+0x1f/0x40 Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> --- block/blk.h | 12 ------------ drivers/md/dm-io.c | 2 +- include/linux/completion.h | 13 +++++++++++++ 3 files changed, 14 insertions(+), 13 deletions(-)