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authorKemeng Shi <shikemeng@huawei.com>2022-12-05 19:57:03 +0800
committerJens Axboe <axboe@kernel.dk>2022-12-05 13:44:34 -0700
commiteb184791821409c37fef4f67638bb56bdaa82900 (patch)
treeaf823af30b990b633edf841d3011ca3ee5988d89 /block
parent84aca0a7e039c8735abc0f89f3f48e9006c0dfc7 (diff)
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')
-rw-r--r--block/blk-throttle.c13
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.