1 files changed, 26 insertions, 0 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 0e6353cf147a..0575197deb4a 100644
--- a/kernel/cpu.c
+++ b/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;