1 files changed, 20 insertions, 7 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c57c4423c688..b732edfddb76 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -434,7 +434,7 @@ struct cgroup_subsys_state *mem_cgroup_css_from_page(struct page *page)
 
         memcg = page->mem_cgroup;
 
-        if (!memcg || !cgroup_on_dfl(memcg->css.cgroup))
+        if (!memcg || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
                 memcg = root_mem_cgroup;
 
         rcu_read_unlock();
@@ -2926,7 +2926,7 @@ static int memcg_activate_kmem(struct mem_cgroup *memcg,
          * of course permitted.
          */
         mutex_lock(&memcg_create_mutex);
-        if (cgroup_has_tasks(memcg->css.cgroup) ||
+        if (cgroup_is_populated(memcg->css.cgroup) ||
             (memcg->use_hierarchy && memcg_has_children(memcg)))
                 err = -EBUSY;
         mutex_unlock(&memcg_create_mutex);
@@ -4066,8 +4066,7 @@ static struct cftype mem_cgroup_legacy_files[] = {
         {
                 .name = "cgroup.event_control",         /* XXX: for compat */
                 .write = memcg_write_event_control,
-                .flags = CFTYPE_NO_PREFIX,
-                .mode = S_IWUGO,
+                .flags = CFTYPE_NO_PREFIX | CFTYPE_WORLD_WRITABLE,
         },
         {
                 .name = "swappiness",
@@ -4834,7 +4833,7 @@ static int mem_cgroup_can_attach(struct cgroup_subsys_state *css,
 {
         struct mem_cgroup *memcg = mem_cgroup_from_css(css);
         struct mem_cgroup *from;
-        struct task_struct *p;
+        struct task_struct *leader, *p;
         struct mm_struct *mm;
         unsigned long move_flags;
         int ret = 0;
@@ -4848,7 +4847,20 @@ static int mem_cgroup_can_attach(struct cgroup_subsys_state *css,
         if (!move_flags)
                 return 0;
 
-        p = cgroup_taskset_first(tset);
+        /*
+         * Multi-process migrations only happen on the default hierarchy
+         * where charge immigration is not used.  Perform charge
+         * immigration if @tset contains a leader and whine if there are
+         * multiple.
+         */
+        p = NULL;
+        cgroup_taskset_for_each_leader(leader, tset) {
+                WARN_ON_ONCE(p);
+                p = leader;
+        }
+        if (!p)
+                return 0;
+
         from = mem_cgroup_from_task(p);
 
         VM_BUG_ON(from == memcg);
@@ -5064,7 +5076,7 @@ static void mem_cgroup_bind(struct cgroup_subsys_state *root_css)
          * guarantees that @root doesn't have any children, so turning it
          * on for the root memcg is enough.
          */
-        if (cgroup_on_dfl(root_css->cgroup))
+        if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
                 root_mem_cgroup->use_hierarchy = true;
         else
                 root_mem_cgroup->use_hierarchy = false;
@@ -5208,6 +5220,7 @@ static struct cftype memory_files[] = {
         {
                 .name = "events",
                 .flags = CFTYPE_NOT_ON_ROOT,
+                .file_offset = offsetof(struct mem_cgroup, events_file),
                 .seq_show = memory_events_show,
         },
         { }     /* terminate */