1 files changed, 70 insertions, 0 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index c729a4c4a1ac..831340e7ad8b 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -28,6 +28,7 @@
 #include <linux/sched/task.h>
 #include <linux/sched/debug.h>
 #include <linux/swap.h>
+#include <linux/syscalls.h>
 #include <linux/timex.h>
 #include <linux/jiffies.h>
 #include <linux/cpuset.h>
@@ -1141,3 +1142,72 @@ void pagefault_out_of_memory(void)
 	out_of_memory(&oc);
 	mutex_unlock(&oom_lock);
 }
+
+SYSCALL_DEFINE2(process_mrelease, int, pidfd, unsigned int, flags)
+{
+#ifdef CONFIG_MMU
+	struct mm_struct *mm = NULL;
+	struct task_struct *task;
+	struct task_struct *p;
+	unsigned int f_flags;
+	bool reap = true;
+	struct pid *pid;
+	long ret = 0;
+
+	if (flags)
+		return -EINVAL;
+
+	pid = pidfd_get_pid(pidfd, &f_flags);
+	if (IS_ERR(pid))
+		return PTR_ERR(pid);
+
+	task = get_pid_task(pid, PIDTYPE_TGID);
+	if (!task) {
+		ret = -ESRCH;
+		goto put_pid;
+	}
+
+	/*
+	 * Make sure to choose a thread which still has a reference to mm
+	 * during the group exit
+	 */
+	p = find_lock_task_mm(task);
+	if (!p) {
+		ret = -ESRCH;
+		goto put_task;
+	}
+
+	mm = p->mm;
+	mmgrab(mm);
+
+	/* If the work has been done already, just exit with success */
+	if (test_bit(MMF_OOM_SKIP, &mm->flags))
+		reap = false;
+	else if (!task_will_free_mem(p)) {
+		reap = false;
+		ret = -EINVAL;
+	}
+	task_unlock(p);
+
+	if (!reap)
+		goto drop_mm;
+
+	if (mmap_read_lock_killable(mm)) {
+		ret = -EINTR;
+		goto drop_mm;
+	}
+	if (!__oom_reap_task_mm(mm))
+		ret = -EAGAIN;
+	mmap_read_unlock(mm);
+
+drop_mm:
+	mmdrop(mm);
+put_task:
+	put_task_struct(task);
+put_pid:
+	put_pid(pid);
+	return ret;
+#else
+	return -ENOSYS;
+#endif /* CONFIG_MMU */
+}