diff options
| author | Nilay Shroff <nilay@linux.ibm.com> | 2025-07-19 18:56:47 +0530 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2025-07-20 13:18:13 -0600 |
| commit | 1966554b2e82b89d4f6490f430ce76a379e23f1f (patch) | |
| tree | 97b50573bcdcafcb0470f7e8c8ba6e6d1cfdc7af | |
| parent | 2680efde75ccdd745da7ae6f5e30026f70439588 (diff) | |
block: fix module reference leak in mq-deadline I/O scheduler
During probe, when the block layer registers a request queue, it
defaults to the mq-deadline I/O scheduler if the device is single-queue
and the mq-deadline module is available. To determine availability, the
elevator_set_default() invokes elevator_find_get(), which increments the
module's reference count. However, this reference is never released,
resulting in a module reference leak that prevents the mq-deadline module
from being unloaded.
This patch fixes the issue by ensuring the acquired module reference is
properly released.
Fixes: 1e44bedbc921 ("block: unifying elevator change")
Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250719132722.769536-1-nilay@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/elevator.c | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/block/elevator.c b/block/elevator.c index ab22542e6cf0..a960bdc869bc 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -719,7 +719,8 @@ void elevator_set_default(struct request_queue *q) .name = "mq-deadline", .no_uevent = true, }; - int err = 0; + int err; + struct elevator_type *e; /* now we allow to switch elevator */ blk_queue_flag_clear(QUEUE_FLAG_NO_ELV_SWITCH, q); @@ -732,12 +733,18 @@ void elevator_set_default(struct request_queue *q) * have multiple queues or mq-deadline is not available, default * to "none". */ - if (elevator_find_get(ctx.name) && (q->nr_hw_queues == 1 || - blk_mq_is_shared_tags(q->tag_set->flags))) + e = elevator_find_get(ctx.name); + if (!e) + return; + + if ((q->nr_hw_queues == 1 || + blk_mq_is_shared_tags(q->tag_set->flags))) { err = elevator_change(q, &ctx); - if (err < 0) - pr_warn("\"%s\" elevator initialization, failed %d, " - "falling back to \"none\"\n", ctx.name, err); + if (err < 0) + pr_warn("\"%s\" elevator initialization, failed %d, falling back to \"none\"\n", + ctx.name, err); + } + elevator_put(e); } void elevator_set_none(struct request_queue *q) |