Update Linux to v5.10.157

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.157.tar.xz

Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
Change-Id: I7b30d9e98d8c465d6b44de8e7433b4a40b3289ba
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 419a814..3d7c557 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -633,7 +633,7 @@
 	 */
 	set_bit(MMF_OOM_SKIP, &mm->flags);
 
-	/* Drop a reference taken by wake_oom_reaper */
+	/* Drop a reference taken by queue_oom_reaper */
 	put_task_struct(tsk);
 }
 
@@ -643,12 +643,12 @@
 		struct task_struct *tsk = NULL;
 
 		wait_event_freezable(oom_reaper_wait, oom_reaper_list != NULL);
-		spin_lock(&oom_reaper_lock);
+		spin_lock_irq(&oom_reaper_lock);
 		if (oom_reaper_list != NULL) {
 			tsk = oom_reaper_list;
 			oom_reaper_list = tsk->oom_reaper_list;
 		}
-		spin_unlock(&oom_reaper_lock);
+		spin_unlock_irq(&oom_reaper_lock);
 
 		if (tsk)
 			oom_reap_task(tsk);
@@ -657,20 +657,46 @@
 	return 0;
 }
 
-static void wake_oom_reaper(struct task_struct *tsk)
+static void wake_oom_reaper(struct timer_list *timer)
+{
+	struct task_struct *tsk = container_of(timer, struct task_struct,
+			oom_reaper_timer);
+	struct mm_struct *mm = tsk->signal->oom_mm;
+	unsigned long flags;
+
+	/* The victim managed to terminate on its own - see exit_mmap */
+	if (test_bit(MMF_OOM_SKIP, &mm->flags)) {
+		put_task_struct(tsk);
+		return;
+	}
+
+	spin_lock_irqsave(&oom_reaper_lock, flags);
+	tsk->oom_reaper_list = oom_reaper_list;
+	oom_reaper_list = tsk;
+	spin_unlock_irqrestore(&oom_reaper_lock, flags);
+	trace_wake_reaper(tsk->pid);
+	wake_up(&oom_reaper_wait);
+}
+
+/*
+ * Give the OOM victim time to exit naturally before invoking the oom_reaping.
+ * The timers timeout is arbitrary... the longer it is, the longer the worst
+ * case scenario for the OOM can take. If it is too small, the oom_reaper can
+ * get in the way and release resources needed by the process exit path.
+ * e.g. The futex robust list can sit in Anon|Private memory that gets reaped
+ * before the exit path is able to wake the futex waiters.
+ */
+#define OOM_REAPER_DELAY (2*HZ)
+static void queue_oom_reaper(struct task_struct *tsk)
 {
 	/* mm is already queued? */
 	if (test_and_set_bit(MMF_OOM_REAP_QUEUED, &tsk->signal->oom_mm->flags))
 		return;
 
 	get_task_struct(tsk);
-
-	spin_lock(&oom_reaper_lock);
-	tsk->oom_reaper_list = oom_reaper_list;
-	oom_reaper_list = tsk;
-	spin_unlock(&oom_reaper_lock);
-	trace_wake_reaper(tsk->pid);
-	wake_up(&oom_reaper_wait);
+	timer_setup(&tsk->oom_reaper_timer, wake_oom_reaper, 0);
+	tsk->oom_reaper_timer.expires = jiffies + OOM_REAPER_DELAY;
+	add_timer(&tsk->oom_reaper_timer);
 }
 
 static int __init oom_init(void)
@@ -680,7 +706,7 @@
 }
 subsys_initcall(oom_init)
 #else
-static inline void wake_oom_reaper(struct task_struct *tsk)
+static inline void queue_oom_reaper(struct task_struct *tsk)
 {
 }
 #endif /* CONFIG_MMU */
@@ -931,7 +957,7 @@
 	rcu_read_unlock();
 
 	if (can_oom_reap)
-		wake_oom_reaper(victim);
+		queue_oom_reaper(victim);
 
 	mmdrop(mm);
 	put_task_struct(victim);
@@ -967,7 +993,7 @@
 	task_lock(victim);
 	if (task_will_free_mem(victim)) {
 		mark_oom_victim(victim);
-		wake_oom_reaper(victim);
+		queue_oom_reaper(victim);
 		task_unlock(victim);
 		put_task_struct(victim);
 		return;
@@ -1065,7 +1091,7 @@
 	 */
 	if (task_will_free_mem(current)) {
 		mark_oom_victim(current);
-		wake_oom_reaper(current);
+		queue_oom_reaper(current);
 		return true;
 	}