diff options
| author | Jan Kara <jack@suse.cz> | 2024-01-23 18:58:26 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2024-02-06 09:44:03 -0700 |
| commit | f814bdda774c183b0cc15ec8f3b6e7c6f4527ba5 (patch) | |
| tree | f423245937edd1e7cf7be59f948d04c8c66ee956 /mm/page-writeback.c | |
| parent | f3c89983cb4fc00be64eb0d5cbcfcdf2cacb965e (diff) | |
blk-wbt: Fix detection of dirty-throttled tasks
The detection of dirty-throttled tasks in blk-wbt has been subtly broken
since its beginning in 2016. Namely if we are doing cgroup writeback and
the throttled task is not in the root cgroup, balance_dirty_pages() will
set dirty_sleep for the non-root bdi_writeback structure. However
blk-wbt checks dirty_sleep only in the root cgroup bdi_writeback
structure. Thus detection of recently throttled tasks is not working in
this case (we noticed this when we switched to cgroup v2 and suddently
writeback was slow).
Since blk-wbt has no easy way to get to proper bdi_writeback and
furthermore its intention has always been to work on the whole device
rather than on individual cgroups, just move the dirty_sleep timestamp
from bdi_writeback to backing_dev_info. That fixes the checking for
recently throttled task and saves memory for everybody as a bonus.
CC: stable@vger.kernel.org
Fixes: b57d74aff9ab ("writeback: track if we're sleeping on progress in balance_dirty_pages()")
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240123175826.21452-1-jack@suse.cz
[axboe: fixup indentation errors]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'mm/page-writeback.c')
| -rw-r--r-- | mm/page-writeback.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index cd4e4ae77c40..cc37fa7f3364 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -1921,7 +1921,7 @@ pause: break; } __set_current_state(TASK_KILLABLE); - wb->dirty_sleep = now; + bdi->last_bdp_sleep = jiffies; io_schedule_timeout(pause); current->dirty_paused_when = now + pause; |