From 9a916798946e5107472cdc714079c0167b8cd251 Mon Sep 17 00:00:00 2001 From: Yu Kuai Date: Sun, 2 Aug 2026 19:25:17 +0800 Subject: [PATCH] blk-cgroup: protect q->blkg_list iteration in blkg_destroy_all() with blkcg_mutex blkg_destroy_all() iterates q->blkg_list without holding blkcg_mutex, which can race with blkg_free_workfn() that removes blkgs from the list while holding blkcg_mutex. Add blkcg_mutex protection around the q->blkg_list iteration to prevent potential list corruption or use-after-free issues. Reviewed-by: Tang Yizhou Signed-off-by: Yu Kuai Reviewed-by: Tao Cui Reviewed-by: Nilay Shroff Link: https://patch.msgid.link/20260802112525.3933753-2-yukuai@kernel.org Signed-off-by: Jens Axboe --- block/blk-cgroup.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index d9676126c5b5..eb0cfb10b859 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -569,6 +569,7 @@ static void blkg_destroy_all(struct gendisk *disk) int i; restart: + mutex_lock(&q->blkcg_mutex); spin_lock_irq(&q->queue_lock); list_for_each_entry(blkg, &q->blkg_list, q_node) { struct blkcg *blkcg = blkg->blkcg; @@ -587,6 +588,7 @@ static void blkg_destroy_all(struct gendisk *disk) if (!(--count)) { count = BLKG_DESTROY_BATCH_SIZE; spin_unlock_irq(&q->queue_lock); + mutex_unlock(&q->blkcg_mutex); cond_resched(); goto restart; } @@ -606,6 +608,7 @@ static void blkg_destroy_all(struct gendisk *disk) q->root_blkg = NULL; spin_unlock_irq(&q->queue_lock); + mutex_unlock(&q->blkcg_mutex); wake_up_var(&q->root_blkg); }