cgroup: remove sane_behavior support on non-default hierarchies

sane_behavior has been used as a development vehicle for the default
unified hierarchy.  Now that the default hierarchy is in place, the
flag became redundant and confusing as its usage is allowed on all
hierarchies.  There are gonna be either the default hierarchy or
legacy ones.  Let's make that clear by removing sane_behavior support
on non-default hierarchies.

This patch replaces cgroup_sane_behavior() with cgroup_on_dfl().  The
comment on top of CGRP_ROOT_SANE_BEHAVIOR is moved to on top of
cgroup_on_dfl() with sane_behavior specific part dropped.

On the default and legacy hierarchies w/o sane_behavior, this
shouldn't cause any behavior differences.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>

1 files changed, 15 insertions, 18 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index f6b33c696224..f9d4807c869f 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1383,12 +1383,9 @@ static int cpuset_can_attach(struct cgroup_subsys_state *css,
 
         mutex_lock(&cpuset_mutex);
 
-        /*
-         * We allow to move tasks into an empty cpuset if sane_behavior
-         * flag is set.
-         */
+        /* allow moving tasks into an empty cpuset if on default hierarchy */
         ret = -ENOSPC;
-        if (!cgroup_sane_behavior(css->cgroup) &&
+        if (!cgroup_on_dfl(css->cgroup) &&
             (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)))
                 goto out_unlock;
 
@@ -2030,7 +2027,7 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs)
         static cpumask_t off_cpus;
         static nodemask_t off_mems;
         bool is_empty;
-        bool sane = cgroup_sane_behavior(cs->css.cgroup);
+        bool on_dfl = cgroup_on_dfl(cs->css.cgroup);
 
 retry:
         wait_event(cpuset_attach_wq, cs->attach_in_progress == 0);
@@ -2054,12 +2051,12 @@ retry:
         mutex_unlock(&callback_mutex);
 
         /*
-         * If sane_behavior flag is set, we need to update tasks' cpumask
-         * for empty cpuset to take on ancestor's cpumask. Otherwise, don't
-         * call update_tasks_cpumask() if the cpuset becomes empty, as
-         * the tasks in it will be migrated to an ancestor.
+         * If on_dfl, we need to update tasks' cpumask for empty cpuset to
+         * take on ancestor's cpumask. Otherwise, don't call
+         * update_tasks_cpumask() if the cpuset becomes empty, as the tasks
+         * in it will be migrated to an ancestor.
          */
-        if ((sane && cpumask_empty(cs->cpus_allowed)) ||
+        if ((on_dfl && cpumask_empty(cs->cpus_allowed)) ||
             (!cpumask_empty(&off_cpus) && !cpumask_empty(cs->cpus_allowed)))
                 update_tasks_cpumask(cs);
 
@@ -2068,12 +2065,12 @@ retry:
         mutex_unlock(&callback_mutex);
 
         /*
-         * If sane_behavior flag is set, we need to update tasks' nodemask
-         * for empty cpuset to take on ancestor's nodemask. Otherwise, don't
-         * call update_tasks_nodemask() if the cpuset becomes empty, as
-         * the tasks in it will be migratd to an ancestor.
+         * If on_dfl, we need to update tasks' nodemask for empty cpuset to
+         * take on ancestor's nodemask. Otherwise, don't call
+         * update_tasks_nodemask() if the cpuset becomes empty, as the
+         * tasks in it will be migratd to an ancestor.
          */
-        if ((sane && nodes_empty(cs->mems_allowed)) ||
+        if ((on_dfl && nodes_empty(cs->mems_allowed)) ||
             (!nodes_empty(off_mems) && !nodes_empty(cs->mems_allowed)))
                 update_tasks_nodemask(cs);
 
@@ -2083,13 +2080,13 @@ retry:
         mutex_unlock(&cpuset_mutex);
 
         /*
-         * If sane_behavior flag is set, we'll keep tasks in empty cpusets.
+         * If on_dfl, we'll keep tasks in empty cpusets.
          *
          * Otherwise move tasks to the nearest ancestor with execution
          * resources.  This is full cgroup operation which will
          * also call back into cpuset.  Should be done outside any lock.
          */
-        if (!sane && is_empty)
+        if (!on_dfl && is_empty)
                 remove_tasks_in_empty_cpuset(cs);
 }