linux-kernel - [PATCH 4.12 18/27] dm mpath: do not lock up a CPU with requeuing activity

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Message-Id: <20170905070923.954501813@linuxfoundation.org>
Date:   Tue,  5 Sep 2017 09:11:34 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Bart Van Assche <bart.vanassche@....com>,
        Laurence Oberman <loberman@...hat.com>,
        Christoph Hellwig <hch@....de>,
        Mike Snitzer <snitzer@...hat.com>
Subject: [PATCH 4.12 18/27] dm mpath: do not lock up a CPU with requeuing activity

4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bart Van Assche <bart.vanassche@....com>

commit 1c23484c355ec360ca2f37914f8a4802c6baeead upstream.

When using the block layer in single queue mode, get_request()
returns ERR_PTR(-EAGAIN) if the queue is dying and the REQ_NOWAIT
flag has been passed to get_request(). Avoid that the kernel
reports soft lockup complaints in this case due to continuous
requeuing activity.

Fixes: 7083abbbf ("dm mpath: avoid that path removal can trigger an infinite loop")
Signed-off-by: Bart Van Assche <bart.vanassche@....com>
Tested-by: Laurence Oberman <loberman@...hat.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Signed-off-by: Mike Snitzer <snitzer@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/md/dm-mpath.c |    1 -
 1 file changed, 1 deletion(-)

--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -504,7 +504,6 @@ static int multipath_clone_and_map(struc
 		if (queue_dying) {
 			atomic_inc(&m->pg_init_in_progress);
 			activate_or_offline_path(pgpath);
-			return DM_MAPIO_REQUEUE;
 		}
 		return DM_MAPIO_DELAY_REQUEUE;
 	}