From: Tejun Heo Date: Wed, 23 May 2012 10:16:21 +0000 (+0200) Subject: blkcg: tg_stats_alloc_lock is an irq lock X-Git-Tag: upstream/snapshot3+hdmi~7336^2 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ff26eaadf4d914e397872b99885d45756104e9ae;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git 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: Tejun Heo Reported-by: Sasha Levin LKML-Reference: <1335339396.16988.80.camel@lappy> Signed-off-by: Jens Axboe --- diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 14dedec..5b06595 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -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); }