From: Muchun Song <songmuchun@bytedance.com>
To: mingo@kernel.org, peterz@infradead.org, juri.lelli@redhat.com,
vincent.guittot@linaro.org
Cc: linux-kernel@vger.kernel.org, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
Muchun Song <songmuchun@bytedance.com>
Subject: [PATCH] sched/fair: Fix call walk_tg_tree_from() without hold rcu_lock
Date: Mon, 6 Apr 2020 20:10:08 +0800 [thread overview]
Message-ID: <20200406121008.62903-1-songmuchun@bytedance.com> (raw)
The walk_tg_tree_from() caller must hold rcu_lock, but the caller
do not call rcu_read_lock() in the unthrottle_cfs_rq(). The
unthrottle_cfs_rq() is used in 3 places. There are
distribute_cfs_runtime(), unthrottle_offline_cfs_rqs() and
tg_set_cfs_bandwidth(). The former 2 already hold the rcu lock,
but the last one does not. So fix it with calling rcu_read_lock()
in the unthrottle_cfs_rq().
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
kernel/sched/fair.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6f05843c76d7d..870853c47b63c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4782,7 +4782,9 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
raw_spin_unlock(&cfs_b->lock);
/* update hierarchical throttle state */
+ rcu_read_lock();
walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
+ rcu_read_unlock();
if (!cfs_rq->load.weight)
return;
--
2.11.0
next reply other threads:[~2020-04-06 12:10 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-06 12:10 Muchun Song [this message]
2020-04-06 18:17 ` [PATCH] sched/fair: Fix call walk_tg_tree_from() without hold rcu_lock bsegall
2020-04-13 15:00 ` [External] " 宋牧春
2020-04-21 13:52 ` Peter Zijlstra
2020-04-21 15:43 ` Paul E. McKenney
2020-04-21 16:24 ` Peter Zijlstra
2020-04-21 17:39 ` Paul E. McKenney
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