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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
        syzbot+b42749a851a47a0f581b@syzkaller.appspotmail.com,
        Ming Lei <ming.lei@redhat.com>,
        Bart Van Assche <bvanassche@acm.org>,
        Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 5.15 04/32] block: release rq qos structures for queue without disk
Date:   Mon, 21 Mar 2022 14:52:40 +0100
Message-Id: <20220321133220.691523932@linuxfoundation.org>
In-Reply-To: <20220321133220.559554263@linuxfoundation.org>
References: <20220321133220.559554263@linuxfoundation.org>
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From: Ming Lei <ming.lei@redhat.com>

commit daaca3522a8e67c46e39ef09c1d542e866f85f3b upstream.

blkcg_init_queue() may add rq qos structures to request queue, previously
blk_cleanup_queue() calls rq_qos_exit() to release them, but commit
8e141f9eb803 ("block: drain file system I/O on del_gendisk")
moves rq_qos_exit() into del_gendisk(), so memory leak is caused
because queues may not have disk, such as un-present scsi luns, nvme
admin queue, ...

Fixes the issue by adding rq_qos_exit() to blk_cleanup_queue() back.

BTW, v5.18 won't need this patch any more since we move
blkcg_init_queue()/blkcg_exit_queue() into disk allocation/release
handler, and patches have been in for-5.18/block.

Cc: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Fixes: 8e141f9eb803 ("block: drain file system I/O on del_gendisk")
Reported-by: syzbot+b42749a851a47a0f581b@syzkaller.appspotmail.com
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220314043018.177141-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 block/blk-core.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -49,6 +49,7 @@
 #include "blk-mq.h"
 #include "blk-mq-sched.h"
 #include "blk-pm.h"
+#include "blk-rq-qos.h"
 
 struct dentry *blk_debugfs_root;
 
@@ -380,6 +381,9 @@ void blk_cleanup_queue(struct request_qu
 	 */
 	blk_freeze_queue(q);
 
+	/* cleanup rq qos structures for queue without disk */
+	rq_qos_exit(q);
+
 	blk_queue_flag_set(QUEUE_FLAG_DEAD, q);
 
 	blk_sync_queue(q);