tree 58cea8112fb0e35d94ff30f9d30184c7b424d66f
parent 95e5d6f62693f27d9011ec307eb32c6126314ea3
author Tejun Heo <tj@kernel.org> 1439934899 -0700
committer Jens Axboe <axboe@fb.com> 1439938156 -0700

cfq-iosched: fix oom cfq_queue ref leak in cfq_set_request()

If the cfq_queue cached in cfq_io_cq is the oom one, cfq_set_request()
replaces it by invoking cfq_get_queue() again without putting the oom
queue leaking the reference it was holding.  While oom queues are not
released through reference counting, they're still reference counted
and this can theoretically lead to the reference count overflowing and
incorrectly invoke the usual release path on it.

Fix it by making cfq_set_request() put the ref it was holding.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>