css_set_lock has been converted to css_set_rwsem, and rwsem can't
nested inside rcu_read_lock.
Signed-off-by: Li Zefan <lizefan@xxxxxxxxxx>
---
kernel/cgroup.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index af4ecc3..0e794ca 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2997,6 +2997,8 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
kernfs_type(kn) != KERNFS_DIR)
return -EINVAL;
+ mutex_lock(&cgroup_mutex);
+
/*
* We aren't being called from kernfs and there's no guarantee on
* @kn->priv's validity. For this and css_tryget_from_dir(),
@@ -3004,10 +3006,12 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
*/
rcu_read_lock();
cgrp = rcu_dereference(kn->priv);
- if (!cgrp) {
+ if (!cgrp || cgroup_is_dead(cgrp)) {
rcu_read_unlock();
+ mutex_unlock(&cgroup_mutex);
return -ENOENT;
}
+ rcu_read_unlock();
css_task_iter_start(&cgrp->dummy_css, &it);
while ((tsk = css_task_iter_next(&it))) {
@@ -3032,7 +3036,7 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
}
css_task_iter_end(&it);
- rcu_read_unlock();
+ mutex_unlock(&cgroup_mutex);
return 0;
}
--
1.8.0.2
--
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