printk a warning to indicate that the io scheduler has been set to none if switching to a new io scheduler fails. Signed-off-by: Jinlong Chen <nickyc975@xxxxxxxxxx> --- block/elevator.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/block/elevator.c b/block/elevator.c index 01aa9f38f22e..1fa45717b1d6 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -683,6 +683,12 @@ int elevator_switch(struct request_queue *q, struct elevator_type *new_e) out_unfreeze: blk_mq_unquiesce_queue(q); blk_mq_unfreeze_queue(q); + + if (ret) { + pr_warn("elv: switch to \"%s\" failed, falling back to \"none\"\n", + new_e->elevator_name); + } + return ret; } -- 2.34.1