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authorChristoph Hellwig <hch@lst.de>2023-02-08 07:35:14 +0100
committerJens Axboe <axboe@kernel.dk>2023-02-09 08:10:45 -0700
commitc43332fe028c252a2a28e46be70a530f64fc3c9d (patch)
treea92d675fb0c4f51de51836f9665f0398b6fc8fe3 /block
parenta872818f484d69944c10be555941b2a73f6e1d4f (diff)
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>
Diffstat (limited to 'block')
-rw-r--r--block/blk-throttle.c3
-rw-r--r--block/genhd.c4
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