elevator: fix loading wrong elevator type for blk-mq devices
The old elevator= boot parameter blindly attempts to load the
same scheduler for mq and !mq devices, leading to a crash if
we specify the wrong one.
Ensure that we only apply this boot parameter to old !mq devices.
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/block/elevator.c b/block/elevator.c
index ef7f594..b2a5516 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -207,11 +207,12 @@ int elevator_init(struct request_queue *q, char *name)
}
/*
- * Use the default elevator specified by config boot param or
- * config option. Don't try to load modules as we could be running
- * off async and request_module() isn't allowed from async.
+ * Use the default elevator specified by config boot param for
+ * non-mq devices, or by config option. Don't try to load modules
+ * as we could be running off async and request_module() isn't
+ * allowed from async.
*/
- if (!e && *chosen_elevator) {
+ if (!e && !q->mq_ops && *chosen_elevator) {
e = elevator_get(chosen_elevator, false);
if (!e)
printk(KERN_ERR "I/O scheduler %s not found\n",