cgroup/cpuset: Skip spread flags update on v2

[ Upstream commit 18f9a4d47527772515ad6cbdac796422566e6440 ]

Cpuset v2 has no spread flags to set. So we can skip spread
flags update if cpuset v2 is being used. Also change the name to
cpuset_update_task_spread_flags() to indicate that there are multiple
spread flags.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Stable-dep-of: 42a11bf5c543 ("cgroup/cpuset: Make cpuset_fork() handle CLONE_INTO_CGROUP properly")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 4c0c317..1c54945 100644 (file)
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -550,11 +550,15 @@ static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
 /*
  * update task's spread flag if cpuset's page/slab spread flag is set
  *
- * Call with callback_lock or cpuset_rwsem held.
+ * Call with callback_lock or cpuset_rwsem held. The check can be skipped
+ * if on default hierarchy.
  */
-static void cpuset_update_task_spread_flag(struct cpuset *cs,
+static void cpuset_update_task_spread_flags(struct cpuset *cs,
                                        struct task_struct *tsk)
 {
+       if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys))
+               return;
+
        if (is_spread_page(cs))
                task_set_spread_page(tsk);
        else
@@ -2165,7 +2169,7 @@ static void update_tasks_flags(struct cpuset *cs)
 
        css_task_iter_start(&cs->css, 0, &it);
        while ((task = css_task_iter_next(&it)))
-               cpuset_update_task_spread_flag(cs, task);
+               cpuset_update_task_spread_flags(cs, task);
        css_task_iter_end(&it);
 }
 
@@ -2547,7 +2551,7 @@ static void cpuset_attach(struct cgroup_taskset *tset)
                WARN_ON_ONCE(set_cpus_allowed_ptr(task, cpus_attach));
 
                cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to);
-               cpuset_update_task_spread_flag(cs, task);
+               cpuset_update_task_spread_flags(cs, task);
        }
 
        /*