5.15-stable review patch. If anyone has any objections, please let me know.
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From: Chengming Zhou zhouchengming@bytedance.com
commit f2aa197e4794bf4c2c0c9570684f86e6fa103e8b upstream.
task_css_set_check() will use rcu_dereference_check() to check for rcu_read_lock_held() on the read-side, which is not true after commit dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock"). This commit drop explicit rcu_read_lock(), change to RCU-sched read-side critical section. So fix the RCU warning by adding check for rcu_read_lock_sched_held().
Fixes: dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock") Reported-by: Linux Kernel Functional Testing lkft@linaro.org Reported-by: syzbot+16e3f2c77e7c5a0113f9@syzkaller.appspotmail.com Signed-off-by: Chengming Zhou zhouchengming@bytedance.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Acked-by: Tejun Heo tj@kernel.org Tested-by: Zhouyi Zhou zhouzhouyi@gmail.com Tested-by: Marek Szyprowski m.szyprowski@samsung.com Link: https://lore.kernel.org/r/20220305034103.57123-1-zhouchengming@bytedance.com Signed-off-by: Ovidiu Panait ovidiu.panait@windriver.com Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/cgroup.h | 1 + 1 file changed, 1 insertion(+)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index f425389ce4bb2..0d97d1cf660f7 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -451,6 +451,7 @@ extern struct mutex cgroup_mutex; extern spinlock_t css_set_lock; #define task_css_set_check(task, __c) \ rcu_dereference_check((task)->cgroups, \ + rcu_read_lock_sched_held() || \ lockdep_is_held(&cgroup_mutex) || \ lockdep_is_held(&css_set_lock) || \ ((task)->flags & PF_EXITING) || (__c))