When ->pre_destroy() is called, it should be guaranteed that
new child cgroup is not created under a cgroup, where pre_destroy()
is running. If not, ->pre_destroy() must check children and
return -EBUSY, which causes warning.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
---
kernel/cgroup.c | 9 +++++++++
1 files changed, 9 insertions(+), 0 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 7a3076b..003ceed 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3970,6 +3970,15 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
mutex_lock(&cgroup_mutex);
+ /*
+ * prevent making child cgroup when ->pre_destroy() is running.
+ */
+ if (test_bit(CGRP_WAIT_ON_RMDIR, &parent->flags)) {
+ mutex_unlock(&cgroup_mutex);
+ atomic_dec(&sb->s_active);
+ return -EBUSY;
+ }
+
init_cgroup_housekeeping(cgrp);
cgrp->parent = parent;
--
1.7.4.1
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