cgroup: disallow rename(2) if sane_behavior (6db8e85c) · Commits · 戴 / test

cgroup's rename(2) isn't a proper migration implementation - it can't move the cgroup to a different parent in the hierarchy. All it can do is swapping the name string for that cgroup. This isn't useful and can mislead users to think that cgroup supports proper cgroup-level migration. Disallow rename(2) if sane_behavior. v2: Fail with -EPERM instead of -EINVAL so that it matches the vfs return value when ->rename is not implemented as suggested by Li. Signed-off-by:

Tejun Heo <tj@kernel.org> Acked-by:

Li Zefan <lizefan@huawei.com>

include/linux/cgroup.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -270,6 +270,8 @@ enum {
		* - "release_agent" and "notify_on_release" are removed.
		* Replacement notification mechanism will be implemented.
		*
		* - rename(2) is disallowed.
		*
		* - memcg: use_hierarchy is on by default and the cgroup file for
		* the flag is not created.
		*/

kernel/cgroup.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -2508,6 +2508,13 @@ static int cgroup_rename(struct inode old_dir, struct dentry old_dentry,

		cgrp = __d_cgrp(old_dentry);

		/*
		* This isn't a proper migration and its usefulness is very
		* limited. Disallow if sane_behavior.
		*/
		if (cgroup_sane_behavior(cgrp))
		return -EPERM;

		name = cgroup_alloc_name(new_dentry);
		if (!name)
		return -ENOMEM;

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