From e3accac1a976e65491a9b9fba82ce8ddbd3d2389 Mon Sep 17 00:00:00 2001 From: Damien Le Moal Date: Tue, 17 Sep 2024 22:32:31 +0900 Subject: [PATCH] block: Fix elv_iosched_local_module handling of "none" scheduler Commit 734e1a860312 ("block: Prevent deadlocks when switching elevators") introduced the function elv_iosched_load_module() to allow loading an elevator module outside of elv_iosched_store() with the target device queue not frozen, to avoid deadlocks. However, the "none" scheduler does not have a module and as a result, elv_iosched_load_module() always returns an error when trying to switch to this valid scheduler. Fix this by ignoring the return value of the request_module() call done by elv_iosched_load_module(). This restores the behavior before commit 734e1a860312, which was to ignore the request_module() result and instead rely on elevator_change() to handle the "none" scheduler case. Reported-by: Shin'ichiro Kawasaki Fixes: 734e1a860312 ("block: Prevent deadlocks when switching elevators") Cc: stable@vger.kernel.org Signed-off-by: Damien Le Moal Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20240917133231.134806-1-dlemoal@kernel.org Signed-off-by: Jens Axboe --- block/elevator.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/block/elevator.c b/block/elevator.c index c355b55d0107..4122026b11f1 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -715,7 +715,9 @@ int elv_iosched_load_module(struct gendisk *disk, const char *buf, strscpy(elevator_name, buf, sizeof(elevator_name)); - return request_module("%s-iosched", strstrip(elevator_name)); + request_module("%s-iosched", strstrip(elevator_name)); + + return 0; } ssize_t elv_iosched_store(struct gendisk *disk, const char *buf,