linux-kernel - [PATCH rfc 3/3] cgroup: remove obsoleted broken_hierarchy and warned_broken

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Message-ID: <20201103212725.3716088-4-guro@fb.com>
Date:   Tue, 3 Nov 2020 13:27:25 -0800
From:   Roman Gushchin <guro@...com>
To:     <linux-mm@...ck.org>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        Shakeel Butt <shakeelb@...gle.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>, Tejun Heo <tj@...nel.org>,
        <linux-kernel@...r.kernel.org>, <kernel-team@...com>,
        Roman Gushchin <guro@...com>
Subject: [PATCH rfc 3/3] cgroup: remove obsoleted broken_hierarchy and warned_broken_hierarchy

With the deprecation of the non-hierarchical mode of the memory
controller there are no more examples of broken hierarchies left.

Let's remove the cgroup core code which was supposed to print
warnings about creating of broken hierarchies.

Signed-off-by: Roman Gushchin <guro@...com>
---
 include/linux/cgroup-defs.h | 15 ---------------
 kernel/cgroup/cgroup.c      |  7 -------
 2 files changed, 22 deletions(-)

diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index fee0b5547cd0..559ee05f86b2 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -668,21 +668,6 @@ struct cgroup_subsys {
 	 */
 	bool threaded:1;
 
-	/*
-	 * If %false, this subsystem is properly hierarchical -
-	 * configuration, resource accounting and restriction on a parent
-	 * cgroup cover those of its children.  If %true, hierarchy support
-	 * is broken in some ways - some subsystems ignore hierarchy
-	 * completely while others are only implemented half-way.
-	 *
-	 * It's now disallowed to create nested cgroups if the subsystem is
-	 * broken and cgroup core will emit a warning message on such
-	 * cases.  Eventually, all subsystems will be made properly
-	 * hierarchical and this will go away.
-	 */
-	bool broken_hierarchy:1;
-	bool warned_broken_hierarchy:1;
-
 	/* the following two fields are initialized automtically during boot */
 	int id;
 	const char *name;
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 621a586e3529..fefa21981027 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -5149,13 +5149,6 @@ static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
 	if (err)
 		goto err_list_del;
 
-	if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
-	    cgroup_parent(parent)) {
-		pr_warn("%s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
-			current->comm, current->pid, ss->name);
-		ss->warned_broken_hierarchy = true;
-	}
-
 	return css;
 
 err_list_del:
-- 
2.26.2