cgroup: re-hash init_css_set after subsystems are initialized
css_sets are hashed by their subsys[] contents and in cgroup_init()
init_css_set is hashed early, before subsystem inits, when all entries
in its subsys[] are NULL, so that cgroup_dfl_root initialization can
find and link to it. As subsystems are initialized,
init_css_set.subsys[] is filled up but the hashing is never updated
making init_css_set hashed in the wrong place. While incorrect, this
doesn't cause a critical failure as css_set management code would
create an identical css_set dynamically.
Fix it by rehashing init_css_set after subsystems are initialized.
While at it, drop unnecessary @key local variable.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 4652950..e97772b 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5266,7 +5266,6 @@
int __init cgroup_init(void)
{
struct cgroup_subsys *ss;
- unsigned long key;
int ssid;
BUILD_BUG_ON(CGROUP_SUBSYS_COUNT > 16);
@@ -5276,9 +5275,12 @@
mutex_lock(&cgroup_mutex);
- /* Add init_css_set to the hash table */
- key = css_set_hash(init_css_set.subsys);
- hash_add(css_set_table, &init_css_set.hlist, key);
+ /*
+ * Add init_css_set to the hash table so that dfl_root can link to
+ * it during init.
+ */
+ hash_add(css_set_table, &init_css_set.hlist,
+ css_set_hash(init_css_set.subsys));
BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0));
@@ -5331,6 +5333,11 @@
ss->bind(init_css_set.subsys[ssid]);
}
+ /* init_css_set.subsys[] has been updated, re-hash */
+ hash_del(&init_css_set.hlist);
+ hash_add(css_set_table, &init_css_set.hlist,
+ css_set_hash(init_css_set.subsys));
+
WARN_ON(sysfs_create_mount_point(fs_kobj, "cgroup"));
WARN_ON(register_filesystem(&cgroup_fs_type));
WARN_ON(register_filesystem(&cgroup2_fs_type));