1 files changed, 46 insertions, 50 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 2bb8c2e98fff..55b297d78adc 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1367,14 +1367,10 @@ static int fmeter_getrate(struct fmeter *fmp)
         return val;
 }
 
-/* Protected by cgroup_lock */
-static cpumask_var_t cpus_attach;
-
 /* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */
 static int cpuset_can_attach(struct cgroup_subsys *ss, struct cgroup *cont,
-                             struct task_struct *tsk, bool threadgroup)
+                             struct task_struct *tsk)
 {
-        int ret;
         struct cpuset *cs = cgroup_cs(cont);
 
         if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
@@ -1391,29 +1387,42 @@ static int cpuset_can_attach(struct cgroup_subsys *ss, struct cgroup *cont,
         if (tsk->flags & PF_THREAD_BOUND)
                 return -EINVAL;
 
-        ret = security_task_setscheduler(tsk);
-        if (ret)
-                return ret;
-        if (threadgroup) {
-                struct task_struct *c;
-
-                rcu_read_lock();
-                list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) {
-                        ret = security_task_setscheduler(c);
-                        if (ret) {
-                                rcu_read_unlock();
-                                return ret;
-                        }
-                }
-                rcu_read_unlock();
-        }
         return 0;
 }
 
-static void cpuset_attach_task(struct task_struct *tsk, nodemask_t *to,
-                               struct cpuset *cs)
+static int cpuset_can_attach_task(struct cgroup *cgrp, struct task_struct *task)
+{
+        return security_task_setscheduler(task);
+}
+
+/*
+ * Protected by cgroup_lock. The nodemasks must be stored globally because
+ * dynamically allocating them is not allowed in pre_attach, and they must
+ * persist among pre_attach, attach_task, and attach.
+ */
+static cpumask_var_t cpus_attach;
+static nodemask_t cpuset_attach_nodemask_from;
+static nodemask_t cpuset_attach_nodemask_to;
+
+/* Set-up work for before attaching each task. */
+static void cpuset_pre_attach(struct cgroup *cont)
+{
+        struct cpuset *cs = cgroup_cs(cont);
+
+        if (cs == &top_cpuset)
+                cpumask_copy(cpus_attach, cpu_possible_mask);
+        else
+                guarantee_online_cpus(cs, cpus_attach);
+
+        guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
+}
+
+/* Per-thread attachment work. */
+static void cpuset_attach_task(struct cgroup *cont, struct task_struct *tsk)
 {
         int err;
+        struct cpuset *cs = cgroup_cs(cont);
+
         /*
          * can_attach beforehand should guarantee that this doesn't fail.
          * TODO: have a better way to handle failure here
@@ -1421,45 +1430,29 @@ static void cpuset_attach_task(struct task_struct *tsk, nodemask_t *to,
         err = set_cpus_allowed_ptr(tsk, cpus_attach);
         WARN_ON_ONCE(err);
 
-        cpuset_change_task_nodemask(tsk, to);
+        cpuset_change_task_nodemask(tsk, &cpuset_attach_nodemask_to);
         cpuset_update_task_spread_flag(cs, tsk);
-
 }
 
 static void cpuset_attach(struct cgroup_subsys *ss, struct cgroup *cont,
-                          struct cgroup *oldcont, struct task_struct *tsk,
-                          bool threadgroup)
+                          struct cgroup *oldcont, struct task_struct *tsk)
 {
         struct mm_struct *mm;
         struct cpuset *cs = cgroup_cs(cont);
         struct cpuset *oldcs = cgroup_cs(oldcont);
-        static nodemask_t to;           /* protected by cgroup_mutex */
 
-        if (cs == &top_cpuset) {
-                cpumask_copy(cpus_attach, cpu_possible_mask);
-        } else {
-                guarantee_online_cpus(cs, cpus_attach);
-        }
-        guarantee_online_mems(cs, &to);
-
-        /* do per-task migration stuff possibly for each in the threadgroup */
-        cpuset_attach_task(tsk, &to, cs);
-        if (threadgroup) {
-                struct task_struct *c;
-                rcu_read_lock();
-                list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) {
-                        cpuset_attach_task(c, &to, cs);
-                }
-                rcu_read_unlock();
-        }
-
-        /* change mm; only needs to be done once even if threadgroup */
-        to = cs->mems_allowed;
+        /*
+         * Change mm, possibly for multiple threads in a threadgroup. This is
+         * expensive and may sleep.
+         */
+        cpuset_attach_nodemask_from = oldcs->mems_allowed;
+        cpuset_attach_nodemask_to = cs->mems_allowed;
         mm = get_task_mm(tsk);
         if (mm) {
-                mpol_rebind_mm(mm, &to);
+                mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
                 if (is_memory_migrate(cs))
-                        cpuset_migrate_mm(mm, &oldcs->mems_allowed, &to);
+                        cpuset_migrate_mm(mm, &cpuset_attach_nodemask_from,
+                                          &cpuset_attach_nodemask_to);
                 mmput(mm);
         }
 }
@@ -1911,6 +1904,9 @@ struct cgroup_subsys cpuset_subsys = {
         .create = cpuset_create,
         .destroy = cpuset_destroy,
         .can_attach = cpuset_can_attach,
+        .can_attach_task = cpuset_can_attach_task,
+        .pre_attach = cpuset_pre_attach,
+        .attach_task = cpuset_attach_task,
         .attach = cpuset_attach,
         .populate = cpuset_populate,
         .post_clone = cpuset_post_clone,