From 36650c9de36801d4126d1cccbb0e085c6f601e1c Mon Sep 17 00:00:00 2001
From: Anton Vorontsov <anton.vorontsov@linaro.org>
Date: Thu, 31 May 2012 16:26:22 -0700
Subject: [PATCH] --- yaml --- r: 309745 b: refs/heads/master c:
 cb79295e20a8088a2fd6a9b3cb5f2d889ec36b4d h: refs/heads/master i:   309743:
 70e36d3c9fc89ff49c8602408809be2527d7b3cb v: v3

---
 [refs]                    |  2 +-
 trunk/include/linux/cpu.h |  1 +
 trunk/kernel/cpu.c        | 26 ++++++++++++++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 5e3f78c8e9e1..9c43af4e0312 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f7505d64f2db5da2d7d94873ddf2cd2524847061
+refs/heads/master: cb79295e20a8088a2fd6a9b3cb5f2d889ec36b4d
diff --git a/trunk/include/linux/cpu.h b/trunk/include/linux/cpu.h
index 7230bb59a06f..2e9b9ebbeb78 100644
--- a/trunk/include/linux/cpu.h
+++ b/trunk/include/linux/cpu.h
@@ -177,6 +177,7 @@ extern void put_online_cpus(void);
 #define hotcpu_notifier(fn, pri)	cpu_notifier(fn, pri)
 #define register_hotcpu_notifier(nb)	register_cpu_notifier(nb)
 #define unregister_hotcpu_notifier(nb)	unregister_cpu_notifier(nb)
+void clear_tasks_mm_cpumask(int cpu);
 int cpu_down(unsigned int cpu);
 
 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
diff --git a/trunk/kernel/cpu.c b/trunk/kernel/cpu.c
index 0e6353cf147a..0575197deb4a 100644
--- a/trunk/kernel/cpu.c
+++ b/trunk/kernel/cpu.c
@@ -10,6 +10,8 @@
 #include <linux/sched.h>
 #include <linux/unistd.h>
 #include <linux/cpu.h>
+#include <linux/oom.h>
+#include <linux/rcupdate.h>
 #include <linux/export.h>
 #include <linux/kthread.h>
 #include <linux/stop_machine.h>
@@ -173,6 +175,30 @@ void __ref unregister_cpu_notifier(struct notifier_block *nb)
 }
 EXPORT_SYMBOL(unregister_cpu_notifier);
 
+void clear_tasks_mm_cpumask(int cpu)
+{
+	struct task_struct *p;
+
+	/*
+	 * This function is called after the cpu is taken down and marked
+	 * offline, so its not like new tasks will ever get this cpu set in
+	 * their mm mask. -- Peter Zijlstra
+	 * Thus, we may use rcu_read_lock() here, instead of grabbing
+	 * full-fledged tasklist_lock.
+	 */
+	rcu_read_lock();
+	for_each_process(p) {
+		struct task_struct *t;
+
+		t = find_lock_task_mm(p);
+		if (!t)
+			continue;
+		cpumask_clear_cpu(cpu, mm_cpumask(t->mm));
+		task_unlock(t);
+	}
+	rcu_read_unlock();
+}
+
 static inline void check_for_tasks(int cpu)
 {
 	struct task_struct *p;