mm: Exclude CDM nodes from task->mems_allowed and root cpuset

ascend inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4JMLR
CVE: NA
-------------------

Task struct's mems_allowed element decides the final nodemask from which
memory can be allocated in the task context irrespective any applicable
memory policy. CDM nodes should not be used for user allocations, its one
of the overall requirements of it's isolation. So they should not be part
of any task's mems_allowed nodemask. System RAM nodemask is used instead
of node_states[N_MEMORY] nodemask during mems_allowed initialization and
it's update during memory hotlugs.
Signed-off-by: NAnshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: NLijun Fang <fanglijun3@huawei.com>
Reviewed-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

kernel/cgroup/cpuset.c

@@ -413,9 +413,11 @@ static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
  */
 static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
 {
-	while (!nodes_intersects(cs->effective_mems, node_states[N_MEMORY]))
+	nodemask_t ram_nodes = system_mem_nodemask();
+
+	while (!nodes_intersects(cs->effective_mems, ram_nodes))
 		cs = parent_cs(cs);
-	nodes_and(*pmask, cs->effective_mems, node_states[N_MEMORY]);
+	nodes_and(*pmask, cs->effective_mems, ram_nodes);
 }
 
 /*
@@ -3168,7 +3170,7 @@ static void cpuset_hotplug_workfn(struct work_struct *work)
 
 	/* fetch the available cpus/mems and find out which changed how */
 	cpumask_copy(&new_cpus, cpu_active_mask);
-	new_mems = node_states[N_MEMORY];
+	new_mems = system_mem_nodemask();
 
 	/*
 	 * If subparts_cpus is populated, it is likely that the check below
@@ -3291,11 +3293,11 @@ static struct notifier_block cpuset_track_online_nodes_nb = {
 void __init cpuset_init_smp(void)
 {
 	cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
-	top_cpuset.mems_allowed = node_states[N_MEMORY];
+	top_cpuset.mems_allowed = system_mem_nodemask();
 	top_cpuset.old_mems_allowed = top_cpuset.mems_allowed;
 
 	cpumask_copy(top_cpuset.effective_cpus, cpu_active_mask);
-	top_cpuset.effective_mems = node_states[N_MEMORY];
+	top_cpuset.effective_mems = system_mem_nodemask();
 
 	register_hotmemory_notifier(&cpuset_track_online_nodes_nb);