diff options
| author | Yu Kuai <yukuai3@huawei.com> | 2025-09-17 15:55:39 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2025-09-17 07:27:29 -0600 |
| commit | 336aec7b06be860477be80a4299263a2e9355789 (patch) | |
| tree | 2647992acf8f1f2e6a6e581caef14ab6c2012b71 | |
| parent | 0b507305a08c134722f363de6fe6f1ba84e313b7 (diff) | |
blk-throttle: fix throtl_data leak during disk release
Tightening the throttle activation check in blk_throtl_activated() to
require both q->td presence and policy bit set introduced a memory leak
during disk release:
blkg_destroy_all() clears the policy bit first during queue deactivation,
causing subsequent blk_throtl_exit() to skip throtl_data cleanup when
blk_throtl_activated() fails policy check.
Idealy we should avoid modifying blk_throtl_exit() activation check because
it's intuitive that blk-throtl start from blk_throtl_init() and end in
blk_throtl_exit(). However, call blk_throtl_exit() before
blkg_destroy_all() will make a long term deadlock problem easier to
trigger[1], hence fix this problem by checking if q->td is NULL from
blk_throtl_exit(), and remove policy deactivation as well since it's
useless.
[1] https://lore.kernel.org/all/CAHj4cs9p9H5yx+ywsb3CMUdbqGPhM+8tuBvhW=9ADiCjAqza9w@mail.gmail.com/#t
Fixes: bd9fd5be6bc0 ("blk-throttle: fix access race during throttle policy activation")
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Closes: https://lore.kernel.org/all/CAHj4cs-p-ZwBEKigBj7T6hQCOo-H68-kVwCrV6ZvRovrr9Z+HA@mail.gmail.com/
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/blk-throttle.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index f510ae072868..2c5b64b1a724 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -1842,12 +1842,15 @@ void blk_throtl_exit(struct gendisk *disk) { struct request_queue *q = disk->queue; - if (!blk_throtl_activated(q)) + /* + * blkg_destroy_all() already deactivate throtl policy, just check and + * free throtl data. + */ + if (!q->td) return; timer_delete_sync(&q->td->service_queue.pending_timer); throtl_shutdown_wq(q); - blkcg_deactivate_policy(disk, &blkcg_policy_throtl); kfree(q->td); } |