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

Greg Kroah-Hartman
2017-09-05T07:14:59Z

From: Bart Van Assche <bart.vanassche@wdc.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@wdc.com>
Tested-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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;
}