Commit 5d7f5ce1 authored by Jens Axboe's avatar Jens Axboe
Browse files

cfq-iosched: don't call wbt_disable_default() with IRQs disabled 



wbt_disable_default() calls del_timer_sync() to wait for the wbt
timer to finish before disabling throttling. We can't do this with
IRQs disable. This fixes a lockdep splat on boot, if non-root
cgroups are used.

Reported-by: default avatarGabriel C <nix.or.die@gmail.com>
Fixes: 87760e5e ("block: hook up writeback throttling")
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent eeeefd41

block/cfq-iosched.c

+13 −12
Original line number Diff line number Diff line
@@ -3758,7 +3758,7 @@ static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 
}



#ifdef CONFIG_CFQ_GROUP_IOSCHED

static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)

static bool check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)

{

	struct cfq_data *cfqd = cic_to_cfqd(cic);

	struct cfq_queue *cfqq;
@@ -3775,15 +3775,7 @@ static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) 
	 * spuriously on a newly created cic but there's no harm.

	 */

	if (unlikely(!cfqd) || likely(cic->blkcg_serial_nr == serial_nr))

		return;



	/*

	 * If we have a non-root cgroup, we can depend on that to

	 * do proper throttling of writes. Turn off wbt for that

	 * case, if it was enabled by default.

	 */

	if (nonroot_cg)

		wbt_disable_default(cfqd->queue);

		return nonroot_cg;



	/*

	 * Drop reference to queues.  New queues will be assigned in new
@@ -3804,9 +3796,13 @@ static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) 
	}



	cic->blkcg_serial_nr = serial_nr;

	return nonroot_cg;

}

#else

static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { }

static inline bool check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)

{

	return false;

}

#endif  /* CONFIG_CFQ_GROUP_IOSCHED */



static struct cfq_queue **
@@ -4448,11 +4444,12 @@ cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio, 
	const int rw = rq_data_dir(rq);

	const bool is_sync = rq_is_sync(rq);

	struct cfq_queue *cfqq;

	bool disable_wbt;



	spin_lock_irq(q->queue_lock);



	check_ioprio_changed(cic, bio);

	check_blkcg_changed(cic, bio);

	disable_wbt = check_blkcg_changed(cic, bio);

new_queue:

	cfqq = cic_to_cfqq(cic, is_sync);

	if (!cfqq || cfqq == &cfqd->oom_cfqq) {
@@ -4488,6 +4485,10 @@ new_queue: 
	rq->elv.priv[0] = cfqq;

	rq->elv.priv[1] = cfqq->cfqg;

	spin_unlock_irq(q->queue_lock);



	if (disable_wbt)

		wbt_disable_default(q);



	return 0;

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE