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| author | Jan Kara <jack@suse.cz> | 2024-01-23 18:58:26 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-02-23 09:25:16 +0100 |
| commit | 601b5540c154b12287e230223cd632bc131d1147 (patch) | |
| tree | 07ee1e1ce5bb34a720c37f4c63faff08181436db /block | |
| parent | 496273439b3cecce97cfaf2de8c210b55356e88d (diff) | |
| download | linux-riscv-601b5540c154b12287e230223cd632bc131d1147.tar.gz linux-riscv-601b5540c154b12287e230223cd632bc131d1147.tar.bz2 linux-riscv-601b5540c154b12287e230223cd632bc131d1147.zip | |
blk-wbt: Fix detection of dirty-throttled tasks
commit f814bdda774c183b0cc15ec8f3b6e7c6f4527ba5 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-wbt.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/block/blk-wbt.c b/block/blk-wbt.c index 0bb613139bec..f8fda9cf583e 100644 --- a/block/blk-wbt.c +++ b/block/blk-wbt.c @@ -165,9 +165,9 @@ static void wb_timestamp(struct rq_wb *rwb, unsigned long *var) */ static bool wb_recent_wait(struct rq_wb *rwb) { - struct bdi_writeback *wb = &rwb->rqos.disk->bdi->wb; + struct backing_dev_info *bdi = rwb->rqos.disk->bdi; - return time_before(jiffies, wb->dirty_sleep + HZ); + return time_before(jiffies, bdi->last_bdp_sleep + HZ); } static inline struct rq_wait *get_rq_wait(struct rq_wb *rwb, |