On 8/21/25 08:06, Yu Kuai wrote:
From: Yu Kuai <yukuai3@xxxxxxxxxx>
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@xxxxxxxxxxxxxxx/
Fixes: f5a6604f7a44 ("block: fix lockdep warning caused by lock dependency in elv_iosched_store")
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
Reviewed-by: Nilay Shroff<nilay@xxxxxxxxxxxxx>
---
block/blk-mq-tag.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index d880c50629d6..5cffa5668d0c 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -622,6 +622,7 @@ int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx,
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 {
/*
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@xxxxxxx +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich
