cgroup: re-hash init_css_set after subsystems are initialized (2378d8b8) · Commits · 戴 / test

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>

kernel/cgroup.c

+11 −4

Original line number	Diff line number	Diff line
		@@ -5266,7 +5266,6 @@ static u16 cgroup_disable_mask __initdata;
		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 @@ int __init cgroup_init(void)

		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 @@ int __init cgroup_init(void)
		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));

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