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Commit 8b5a5a9d authored Apr 01, 2012 by Tejun Heo

cgroup: deprecate remount option changes



This patch marks the following features for deprecation.

* Rebinding subsys by remount: Never reached useful state - only works
  on empty hierarchies.

* release_agent update by remount: release_agent itself will be
  replaced with conventional fsnotify notification.

v2: Lennart pointed out that "name=" is necessary for mounts w/o any
    controller attached.  Drop "name=" deprecation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Lennart Poettering <mzxreary@0pointer.de>

parent dd775ae2

Documentation/feature-removal-schedule.txt

+9 −0

Original line number	Original line	Diff line number	Diff line
	@@ -539,3 +539,12 @@ Why: There appear to be no production users of the get_robust_list syscall,
	of ASLR. It was only ever intended for debugging, so it should be		of ASLR. It was only ever intended for debugging, so it should be
	removed.		removed.
	Who: Kees Cook <keescook@chromium.org>		Who: Kees Cook <keescook@chromium.org>

			----------------------------

			What: cgroup option updates via remount
			When: March 2013
			Why: Remount currently allows changing bound subsystems and
			release_agent. Rebinding is hardly useful as it only works
			when the hierarchy is empty and release_agent itself should be
			replaced with conventional fsnotify.

kernel/cgroup.c

+5 −0

Original line number	Original line	Diff line number	Diff line
	@@ -1294,6 +1294,11 @@ static int cgroup_remount(struct super_block sb, int flags, char *data)
	if (ret)		if (ret)
	goto out_unlock;		goto out_unlock;

			/* See feature-removal-schedule.txt */
			if (opts.subsys_bits != root->actual_subsys_bits \|\| opts.release_agent)
			pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n",
			task_tgid_nr(current), current->comm);

	/* Don't allow flags or name to change at remount */		/* Don't allow flags or name to change at remount */
	if (opts.flags != root->flags \|\|		if (opts.flags != root->flags \|\|
	(opts.name && strcmp(opts.name, root->name))) {		(opts.name && strcmp(opts.name, root->name))) {