[PATCH 2/3] mm, memcg: introduce a new helper task_in_memcg_oom_set()

[Yafang Shao <laoar.shao@gmail.com>]

A new helper task_in_memcg_oom_set() is introduced for later use. It
will be used to bail out from the charge path if no victim can be found
in memcg oom.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 include/linux/memcontrol.h | 25 +++++++++++++++++++++++++
 mm/memcontrol.c            | 12 ++----------
 2 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 98bd8fb2f5c7..767bac135787 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -565,6 +565,23 @@ static inline bool task_in_memcg_oom(struct task_struct *p)
 	return p->memcg_in_oom;
 }
 
+/* Bail out from the charge path if no victim found in memcg oom */
+static inline enum oom_status task_in_memcg_oom_set(struct task_struct *p,
+						    struct mem_cgroup *memcg,
+						    gfp_t mask,
+						    int order)
+{
+	if (!current->in_user_fault)
+		return OOM_SKIPPED;
+
+	css_get(&memcg->css);
+	p->memcg_in_oom = memcg;
+	p->memcg_oom_gfp_mask = mask;
+	p->memcg_oom_order = order;
+
+	return OOM_ASYNC;
+}
+
 bool mem_cgroup_oom_synchronize(bool wait);
 struct mem_cgroup *mem_cgroup_get_oom_group(struct task_struct *victim,
 					    struct mem_cgroup *oom_domain);
@@ -1031,6 +1048,14 @@ static inline bool task_in_memcg_oom(struct task_struct *p)
 	return false;
 }
 
+static inline enum oom_status task_in_memcg_oom_set(struct task_struct *p,
+						    struct mem_cgroup *memcg,
+						    gfp_t mask,
+						    int order)
+{
+	return OOM_SUCCESS;
+}
+
 static inline bool mem_cgroup_oom_synchronize(bool wait)
 {
 	return false;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 22418b55804f..d6cb1b786045 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1800,16 +1800,8 @@ static enum oom_status mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int
 	 * Please note that mem_cgroup_out_of_memory might fail to find a
 	 * victim and then we have to bail out from the charge path.
 	 */
-	if (memcg->oom_kill_disable) {
-		if (!current->in_user_fault)
-			return OOM_SKIPPED;
-		css_get(&memcg->css);
-		current->memcg_in_oom = memcg;
-		current->memcg_oom_gfp_mask = mask;
-		current->memcg_oom_order = order;
-
-		return OOM_ASYNC;
-	}
+	if (memcg->oom_kill_disable)
+		return task_in_memcg_oom_set(current, memcg, mask, order);
 
 	mem_cgroup_mark_under_oom(memcg);
 
-- 
2.18.2