diff options
| author | Christoph Hellwig <hch@lst.de> | 2023-02-08 07:35:14 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2023-02-09 16:10:45 +0100 |
| commit | c43332fe028c252a2a28e46be70a530f64fc3c9d (patch) | |
| tree | a92d675fb0c4f51de51836f9665f0398b6fc8fe3 | |
| parent | Merge branch 'md-next' of https://git.kernel.org/pub/scm/linux/kernel/git/son... (diff) | |
| download | linux-c43332fe028c252a2a28e46be70a530f64fc3c9d.tar.xz linux-c43332fe028c252a2a28e46be70a530f64fc3c9d.zip | |
blk-cgroup: delay calling blkcg_exit_disk until disk_release
While del_gendisk ensures there is no outstanding I/O on the queue,
it can't prevent block layer users from building new I/O.
This leads to a NULL ->root_blkg reference in bio_associate_blkg when
allocating a new bio on a shut down file system. Delay freeing the
blk-cgroup subsystems from del_gendisk until disk_release to make
sure the blkg and throttle information is still avaŃ–lable for bio
submitters, even if those bios will immediately fail.
This now can cause a case where disk_release is called on a disk
that hasn't been added. That's mostly harmless, except for a case
in blk_throttl_exit that now needs to check for a NULL ->td pointer.
Fixes: 178fa7d49815 ("blk-cgroup: delay blk-cgroup initialization until add_disk")
Reported-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230208063514.171485-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/blk-throttle.c | 3 | ||||
| -rw-r--r-- | block/genhd.c | 4 |
2 files changed, 4 insertions, 3 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 902203bdddb4..e7bd7050d684 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -2411,7 +2411,8 @@ void blk_throtl_exit(struct gendisk *disk) { struct request_queue *q = disk->queue; - BUG_ON(!q->td); + if (!q->td) + return; del_timer_sync(&q->td->service_queue.pending_timer); throtl_shutdown_wq(q); blkcg_deactivate_policy(disk, &blkcg_policy_throtl); diff --git a/block/genhd.c b/block/genhd.c index 7e031559bf51..65373738c70b 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -668,8 +668,6 @@ void del_gendisk(struct gendisk *disk) rq_qos_exit(q); blk_mq_unquiesce_queue(q); - blkcg_exit_disk(disk); - /* * If the disk does not own the queue, allow using passthrough requests * again. Else leave the queue frozen to fail all I/O. @@ -1166,6 +1164,8 @@ static void disk_release(struct device *dev) might_sleep(); WARN_ON_ONCE(disk_live(disk)); + blkcg_exit_disk(disk); + /* * To undo the all initialization from blk_mq_init_allocated_queue in * case of a probe failure where add_disk is never called we have to |