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Commit ff26eaad authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

blkcg: tg_stats_alloc_lock is an irq lock 



tg_stats_alloc_lock nests inside queue lock and should always be held
with irq disabled.  throtl_pd_{init|exit}() were using non-irqsafe
spinlock ops which triggered inverse lock ordering via irq warning via
RCU freeing of blkg invoking throtl_pd_exit() w/o disabling IRQ.

Update both functions to use irq safe operations.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Reported-by: default avatarSasha Levin <sasha.levin@oracle.com>
LKML-Reference: <1335339396.16988.80.camel@lappy>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 0b7877d4

block/blk-throttle.c

+6 −4
Original line number Diff line number Diff line
@@ -219,6 +219,7 @@ alloc_stats: 
static void throtl_pd_init(struct blkcg_gq *blkg)

{

	struct throtl_grp *tg = blkg_to_tg(blkg);

	unsigned long flags;



	RB_CLEAR_NODE(&tg->rb_node);

	bio_list_init(&tg->bio_lists[0]);
@@ -235,19 +236,20 @@ static void throtl_pd_init(struct blkcg_gq *blkg) 
	 * but percpu allocator can't be called from IO path.  Queue tg on

	 * tg_stats_alloc_list and allocate from work item.

	 */

	spin_lock(&tg_stats_alloc_lock);

	spin_lock_irqsave(&tg_stats_alloc_lock, flags);

	list_add(&tg->stats_alloc_node, &tg_stats_alloc_list);

	queue_delayed_work(system_nrt_wq, &tg_stats_alloc_work, 0);

	spin_unlock(&tg_stats_alloc_lock);

	spin_unlock_irqrestore(&tg_stats_alloc_lock, flags);

}



static void throtl_pd_exit(struct blkcg_gq *blkg)

{

	struct throtl_grp *tg = blkg_to_tg(blkg);

	unsigned long flags;



	spin_lock(&tg_stats_alloc_lock);

	spin_lock_irqsave(&tg_stats_alloc_lock, flags);

	list_del_init(&tg->stats_alloc_node);

	spin_unlock(&tg_stats_alloc_lock);

	spin_unlock_irqrestore(&tg_stats_alloc_lock, flags);



	free_percpu(tg->stats_cpu);

}