1 files changed, 46 insertions, 50 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 2bb8c2e..55b297d 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,