6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yu Kuai [ Upstream commit 25656304dabd26198ec69460c594a19d086ef099 ] blkcg_print_one_stat() will be called for each blkg: - access blkg->iostat, which is freed from rcu callback blkg_free_workfn(); - access policy data from pd_stat_fn(), which is freed from pd_free_fn(), while pd_free_fn() can be called by removing blkcg or deactivating policy; Take blkcg->lock while iterating so the blkgs stay online and both blkg->iostat and policy data for activated policies stay valid. Use irq-safe locking because blkcg->lock can be nested under q->queue_lock, which is used from IRQ completion paths. Prepare to convert protecting blkgs from request_queue with mutex. Signed-off-by: Yu Kuai Link: https://patch.msgid.link/05799877e720dcd300e2ddd4625e8e162959d7cc.1780621988.git.yukuai@fygo.io Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-cgroup.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index b108e934a1427..cd30f2ca561f5 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -1201,13 +1201,10 @@ static int blkcg_print_stat(struct seq_file *sf, void *v) else cgroup_rstat_flush(blkcg->css.cgroup); - rcu_read_lock(); - hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { - spin_lock_irq(&blkg->q->queue_lock); + guard(spinlock_irq)(&blkcg->lock); + hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) blkcg_print_one_stat(blkg, sf); - spin_unlock_irq(&blkg->q->queue_lock); - } - rcu_read_unlock(); + return 0; } -- 2.53.0