1 files changed, 17 insertions, 13 deletions

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 1ddabefcfb5a..3934ff500878 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -994,6 +994,7 @@ static void oom_kill_process(struct oom_control *oc, const char *message)
 	 * If necessary, kill all tasks in the selected memory cgroup.
 	 */
 	if (oom_group) {
+		memcg_memory_event(oom_group, MEMCG_OOM_GROUP_KILL);
 		mem_cgroup_print_oom_group(oom_group);
 		mem_cgroup_scan_tasks(oom_group, oom_kill_memcg_member,
 				      (void *)message);
@@ -1057,7 +1058,7 @@ bool out_of_memory(struct oom_control *oc)
 
 	if (!is_memcg_oom(oc)) {
 		blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
-		if (freed > 0)
+		if (freed > 0 && !is_sysrq_oom(oc))
 			/* Got some memory back in the last second. */
 			return true;
 	}
@@ -1169,15 +1170,15 @@ SYSCALL_DEFINE2(process_mrelease, int, pidfd, unsigned int, flags)
 		goto put_task;
 	}
 
-	if (mmget_not_zero(p->mm)) {
-		mm = p->mm;
-		if (task_will_free_mem(p))
-			reap = true;
-		else {
-			/* Error only if the work has not been done already */
-			if (!test_bit(MMF_OOM_SKIP, &mm->flags))
-				ret = -EINVAL;
-		}
+	mm = p->mm;
+	mmgrab(mm);
+
+	if (task_will_free_mem(p))
+		reap = true;
+	else {
+		/* Error only if the work has not been done already */
+		if (!test_bit(MMF_OOM_SKIP, &mm->flags))
+			ret = -EINVAL;
 	}
 	task_unlock(p);
 
@@ -1188,13 +1189,16 @@ SYSCALL_DEFINE2(process_mrelease, int, pidfd, unsigned int, flags)
 		ret = -EINTR;
 		goto drop_mm;
 	}
-	if (!__oom_reap_task_mm(mm))
+	/*
+	 * Check MMF_OOM_SKIP again under mmap_read_lock protection to ensure
+	 * possible change in exit_mmap is seen
+	 */
+	if (!test_bit(MMF_OOM_SKIP, &mm->flags) && !__oom_reap_task_mm(mm))
 		ret = -EAGAIN;
 	mmap_read_unlock(mm);
 
 drop_mm:
-	if (mm)
-		mmput(mm);
+	mmdrop(mm);
 put_task:
 	put_task_struct(task);
 	return ret;