[PATCH] block: CFQ refcounting fix

I ran across a memory leak related to the cfq scheduler. The cfq
init function increments the refcnt of the associated request_queue.

This refcount gets decremented in cfq's exit function. Since blk_cleanup_queue
only calls the elevator exit function when its refcnt goes to zero, the
request_q never gets cleaned up. It didn't look like other io schedulers were
incrementing this refcnt, so I removed the refcnt increment and it fixed the
memory leak for me.

To reproduce the problem, simply use cfq and use the scsi_host scan sysfs
attribute to scan "- - -" repeatedly on a scsi host and watch the memory
vanish.

Signed-off-by: Brian King <brking@us.ibm.com>
Acked-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/block/cfq-iosched.c b/drivers/block/cfq-iosched.c
index cd056e7..30c0903 100644 (file)
--- a/drivers/block/cfq-iosched.c
+++ b/drivers/block/cfq-iosched.c
@@ -2260,8 +2260,6 @@ static void cfq_put_cfqd(struct cfq_data *cfqd)
        if (!atomic_dec_and_test(&cfqd->ref))
                return;
 
-       blk_put_queue(q);
-
        cfq_shutdown_timer_wq(cfqd);
        q->elevator->elevator_data = NULL;
 
@@ -2318,7 +2316,6 @@ static int cfq_init_queue(request_queue_t *q, elevator_t *e)
        e->elevator_data = cfqd;
 
        cfqd->queue = q;
-       atomic_inc(&q->refcnt);
 
        cfqd->max_queued = q->nr_requests / 4;
        q->nr_batching = cfq_queued;