diff options
| author | Waiman Long <longman@redhat.com> | 2022-02-02 22:31:03 -0500 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2022-02-03 05:59:01 -1000 |
| commit | 2bdfd2825c9662463371e6691b1a794e97fa36b4 (patch) | |
| tree | c677349e0e219e802f1c94ad20b75b9aca42a2c3 | |
| parent | 24f6008564183aa120d07c03d9289519c2fe02af (diff) | |
| download | linux-dm-2bdfd2825c9662463371e6691b1a794e97fa36b4.tar.gz | |
cgroup/cpuset: Fix "suspicious RCU usage" lockdep warning
It was found that a "suspicious RCU usage" lockdep warning was issued
with the rcu_read_lock() call in update_sibling_cpumasks(). It is
because the update_cpumasks_hier() function may sleep. So we have
to release the RCU lock, call update_cpumasks_hier() and reacquire
it afterward.
Also add a percpu_rwsem_assert_held() in update_sibling_cpumasks()
instead of stating that in the comment.
Fixes: 4716909cc5c5 ("cpuset: Track cpusets that use parent's effective_cpus")
Signed-off-by: Waiman Long <longman@redhat.com>
Tested-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Phil Auld <pauld@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
| -rw-r--r-- | kernel/cgroup/cpuset.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 804ff5738c5f7a..4c7254e8f49a54 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1550,10 +1550,15 @@ static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs, struct cpuset *sibling; struct cgroup_subsys_state *pos_css; + percpu_rwsem_assert_held(&cpuset_rwsem); + /* * Check all its siblings and call update_cpumasks_hier() * if their use_parent_ecpus flag is set in order for them * to use the right effective_cpus value. + * + * The update_cpumasks_hier() function may sleep. So we have to + * release the RCU read lock before calling it. */ rcu_read_lock(); cpuset_for_each_child(sibling, pos_css, parent) { @@ -1561,8 +1566,13 @@ static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs, continue; if (!sibling->use_parent_ecpus) continue; + if (!css_tryget_online(&sibling->css)) + continue; + rcu_read_unlock(); update_cpumasks_hier(sibling, tmp); + rcu_read_lock(); + css_put(&sibling->css); } rcu_read_unlock(); } |