Commit 38f18527 authored Sep 06, 2005 by Brian King Committed by Linus Torvalds Sep 07, 2005

[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>

parent 49e31cba

drivers/block/cfq-iosched.c

+0 −3

Original line number	Original line	Diff line number	Diff line
	@@ -2260,8 +2260,6 @@ static void cfq_put_cfqd(struct cfq_data *cfqd)
	if (!atomic_dec_and_test(&cfqd->ref))		if (!atomic_dec_and_test(&cfqd->ref))
	return;		return;

	blk_put_queue(q);

	cfq_shutdown_timer_wq(cfqd);		cfq_shutdown_timer_wq(cfqd);
	q->elevator->elevator_data = NULL;		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;		e->elevator_data = cfqd;

	cfqd->queue = q;		cfqd->queue = q;
	atomic_inc(&q->refcnt);

	cfqd->max_queued = q->nr_requests / 4;		cfqd->max_queued = q->nr_requests / 4;
	q->nr_batching = cfq_queued;		q->nr_batching = cfq_queued;