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| author | Kemeng Shi <shikemeng@huawei.com> | 2022-12-05 19:57:03 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2022-12-05 13:44:34 -0700 |
| commit | eb184791821409c37fef4f67638bb56bdaa82900 (patch) | |
| tree | af823af30b990b633edf841d3011ca3ee5988d89 /block/blk-throttle.c | |
| parent | 84aca0a7e039c8735abc0f89f3f48e9006c0dfc7 (diff) | |
| download | lwn-eb184791821409c37fef4f67638bb56bdaa82900.tar.gz lwn-eb184791821409c37fef4f67638bb56bdaa82900.zip | |
blk-throttle: ignore cgroup without io queued in blk_throtl_cancel_bios
Ignore cgroup without io queued in blk_throtl_cancel_bios for two
reasons:
1. Save cpu cycle for trying to dispatch cgroup which is no io queued.
2. Avoid non-consistent state that cgroup is inserted to service queue
without THROTL_TG_PENDING set as tg_update_disptime will unconditional
re-insert cgroup to service queue. If we are on the default hierarchy,
IO dispatched from child in tg_dispatch_one_bio will trigger inserting
cgroup to service queue without erase first and ruin the tree.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-4-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-throttle.c')
| -rw-r--r-- | block/blk-throttle.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 2444ebf5f11d..75010110d481 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -1738,7 +1738,18 @@ void blk_throtl_cancel_bios(struct gendisk *disk) * Set the flag to make sure throtl_pending_timer_fn() won't * stop until all throttled bios are dispatched. */ - blkg_to_tg(blkg)->flags |= THROTL_TG_CANCELING; + tg->flags |= THROTL_TG_CANCELING; + + /* + * Do not dispatch cgroup without THROTL_TG_PENDING or cgroup + * will be inserted to service queue without THROTL_TG_PENDING + * set in tg_update_disptime below. Then IO dispatched from + * child in tg_dispatch_one_bio will trigger double insertion + * and corrupt the tree. + */ + if (!(tg->flags & THROTL_TG_PENDING)) + continue; + /* * Update disptime after setting the above flag to make sure * throtl_select_dispatch() won't exit without dispatching. |