[PATCH 5.15.y] block: fix resource leak in blk_register_queue() error path

[PATCH 5.15.y] block: fix resource leak in blk_register_queue() error path

[Robert Garcia]

From: Zheng Qixing <zhengqixing@huawei.com>

[ Upstream commit 40f2eb9b531475dd01b683fdaf61ca3cfd03a51e ]

When registering a queue fails after blk_mq_sysfs_register() is
successful but the function later encounters an error, we need
to clean up the blk_mq_sysfs resources.

Add the missing blk_mq_sysfs_unregister() call in the error path
to properly clean up these resources and prevent a memory leak.

Fixes: 320ae51feed5 ("blk-mq: new multi-queue block IO queueing mechanism")
Signed-off-by: Zheng Qixing <zhengqixing@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20250412092554.475218-1-zhengqixing@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
[ Change disk to q in blk_mq_sysfs_unregister(). ]
Signed-off-by: Robert Garcia <rob_garcia@163.com>
---
 block/blk-sysfs.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 4ea84e46a665..c1917992e619 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -900,6 +900,8 @@ int blk_register_queue(struct gendisk *disk)
 	if (q->elevator)
 		kobject_uevent(&q->elevator->kobj, KOBJ_ADD);
 	mutex_unlock(&q->sysfs_lock);
+	if (queue_is_mq(q))
+		blk_mq_sysfs_unregister(q);
 
 	ret = 0;
 unlock:
-- 
2.34.1

Re: [PATCH 5.15.y] block: fix resource leak in blk_register_queue() error path

[Sasha Levin]

> [PATCH 5.15.y] block: fix resource leak in blk_register_queue()
> error path

This patch places blk_mq_sysfs_unregister(q) on the success path (after
kobject_uevent, before 'ret = 0') rather than on the error path.  As written,
this would unregister sysfs on every successful blk_register_queue() call,
breaking block device initialization.