cpuset: allow writing offlined masks to cpuset.cpus/mems

As the configured masks won't be limited by its parent, and the top
cpuset's masks won't change when hotplug happens, it's natural to
allow writing offlined masks to the configured masks.

If on default hierarchy:

	# echo 0 > /sys/devices/system/cpu/cpu1/online
	# mkdir /cpuset/sub
	# echo 1 > /cpuset/sub/cpuset.cpus
	# cat /cpuset/sub/cpuset.cpus
	1

If on legacy hierarchy:

	# echo 0 > /sys/devices/system/cpu/cpu1/online
	# mkdir /cpuset/sub
	# echo 1 > /cpuset/sub/cpuset.cpus
	-bash: echo: write error: Invalid argument

Note the checks don't need to be gated by cgroup_on_dfl, because we've
initialized top_cpuset.{cpus,mems}_allowed accordingly in cpuset_bind().

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index c47cb940712e..65878a74a66b 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -929,7 +929,8 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
                 if (retval < 0)
                         return retval;
 
-                if (!cpumask_subset(trialcs->cpus_allowed, cpu_active_mask))
+                if (!cpumask_subset(trialcs->cpus_allowed,
+                                    top_cpuset.cpus_allowed))
                         return -EINVAL;
         }
 
@@ -1186,8 +1187,8 @@ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
                         goto done;
 
                 if (!nodes_subset(trialcs->mems_allowed,
-                                node_states[N_MEMORY])) {
-                        retval =  -EINVAL;
+                                  top_cpuset.mems_allowed)) {
+                        retval = -EINVAL;
                         goto done;
                 }
         }