[PATCH] dm: release the sysfs kobject when its initialization fails

[Wentao Liang <vulab@iscas.ac.cn>]

dm_sysfs_init() uses kobject_init_and_add(), which requires a matching
put even when adding the object fails. dm_setup_md_queue() currently
unwinds the disk and holder links without releasing this object. Since
md->type is still DM_TYPE_NONE, cleanup_mapped_device() also skips the
sysfs cleanup, leaving the initialized kobject behind.

Call dm_sysfs_exit() before unwinding a failed sysfs initialization. This
both puts the kobject and waits for its release callback, including when
CONFIG_DEBUG_KOBJECT_RELEASE delays that callback, before the mapped
device can be freed or its queue setup retried.

Fixes: 784aae735d9b ("dm: add name and uuid to sysfs")
Cc: stable@vger.kernel.org
Assisted-by: DeepSeek-V4.1-Flash and OpenAI Codex
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
---
 drivers/md/dm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 1881d86111fb..08b87fd6f955 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2647,8 +2647,10 @@ int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t)
 	mutex_unlock(&md->table_devices_lock);
 
 	r = dm_sysfs_init(md);
-	if (r)
+	if (r) {
+		dm_sysfs_exit(md);
 		goto lock_out_undo_holders;
+	}
 
 	md->type = type;
 
-- 
2.34.1