6.16-stable review patch. If anyone has any objections, please let me know.
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From: Yu Kuai yukuai3@huawei.com
commit ba28afbd9eff2a6370f23ef4e6a036ab0cfda409 upstream.
In the case user trigger tags grow by queue sysfs attribute nr_requests, hctx->sched_tags will be freed directly and replaced with a new allocated tags, see blk_mq_tag_update_depth().
The problem is that hctx->sched_tags is from elevator->et->tags, while et->tags is still the freed tags, hence later elevator exit will try to free the tags again, causing kernel panic.
Fix this problem by replacing et->tags with new allocated tags as well.
Noted there are still some long term problems that will require some refactor to be fixed thoroughly[1].
[1] https://lore.kernel.org/all/20250815080216.410665-1-yukuai1@huaweicloud.com/ Fixes: f5a6604f7a44 ("block: fix lockdep warning caused by lock dependency in elv_iosched_store")
Signed-off-by: Yu Kuai yukuai3@huawei.com Reviewed-by: Ming Lei ming.lei@redhat.com Reviewed-by: Nilay Shroff nilay@linux.ibm.com Reviewed-by: Hannes Reinecke hare@suse.de Reviewed-by: Li Nan linan122@huawei.com Link: https://lore.kernel.org/r/20250821060612.1729939-3-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- block/blk-mq-tag.c | 1 + 1 file changed, 1 insertion(+)
--- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -622,6 +622,7 @@ int blk_mq_tag_update_depth(struct blk_m return -ENOMEM;
blk_mq_free_map_and_rqs(set, *tagsptr, hctx->queue_num); + hctx->queue->elevator->et->tags[hctx->queue_num] = new; *tagsptr = new; } else { /*