Commit 78f6519e authored by Michal Koutný's avatar Michal Koutný Committed by Tejun Heo
Browse files

cgroup: Add deprecation message to legacy freezer controller 



As explained in the commit 76f969e8 ("cgroup: cgroup v2 freezer"),
the original freezer is imperfect, some users may unwittingly rely on it
when there exists the alternative of v2. Print a message when it happens
and explain that in the docs.

Signed-off-by: default avatarMichal Koutný <mkoutny@suse.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent fd4fd0a8

Documentation/admin-guide/cgroup-v1/freezer-subsystem.rst

+4 −0
Original line number Diff line number Diff line
@@ -125,3 +125,7 @@ to unfreeze all tasks in the container:: 


This is the basic mechanism which should do the right thing for user space task

in a simple scenario.



This freezer implementation is affected by shortcomings (see commit

76f969e8948d8 ("cgroup: cgroup v2 freezer")) and cgroup v2 freezer is

recommended.

kernel/cgroup/legacy_freezer.c

+4 −2
Original line number Diff line number Diff line
@@ -430,9 +430,11 @@ static ssize_t freezer_write(struct kernfs_open_file *of, 


	if (strcmp(buf, freezer_state_strs(0)) == 0)

		freeze = false;

	else if (strcmp(buf, freezer_state_strs(CGROUP_FROZEN)) == 0)

	else if (strcmp(buf, freezer_state_strs(CGROUP_FROZEN)) == 0) {

		pr_info_once("Freezing with imperfect legacy cgroup freezer. "

			     "See cgroup.freeze of cgroup v2\n");

		freeze = true;

	else

	} else

		return -EINVAL;



	freezer_change_state(css_freezer(of_css(of)), freeze);