From: Ming Lei Date: Fri, 17 Nov 2023 02:35:22 +0000 (+0800) Subject: blk-throttle: fix lockdep warning of "cgroup_mutex or RCU read lock required!" X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=27b13e209ddca5979847a1b57890e0372c1edcee;p=linux.git blk-throttle: fix lockdep warning of "cgroup_mutex or RCU read lock required!" Inside blkg_for_each_descendant_pre(), both css_for_each_descendant_pre() and blkg_lookup() requires RCU read lock, and either cgroup_assert_mutex_or_rcu_locked() or rcu_read_lock_held() is called. Fix the warning by adding rcu read lock. Reported-by: Changhui Zhong Signed-off-by: Ming Lei Link: https://lore.kernel.org/r/20231117023527.3188627-2-ming.lei@redhat.com Signed-off-by: Jens Axboe --- diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 13e4377a8b286..16f5766620a41 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -1320,6 +1320,7 @@ static void tg_conf_updated(struct throtl_grp *tg, bool global) tg_bps_limit(tg, READ), tg_bps_limit(tg, WRITE), tg_iops_limit(tg, READ), tg_iops_limit(tg, WRITE)); + rcu_read_lock(); /* * Update has_rules[] flags for the updated tg's subtree. A tg is * considered to have rules if either the tg itself or any of its @@ -1347,6 +1348,7 @@ static void tg_conf_updated(struct throtl_grp *tg, bool global) this_tg->latency_target = max(this_tg->latency_target, parent_tg->latency_target); } + rcu_read_unlock(); /* * We're already holding queue_lock and know @tg is valid. Let's