[RFC 1/2] mm: oom: expose expedite_reclaim to use oom_reaper outside of oom_kill.c

[Suren Baghdasaryan <surenb@google.com>]

Create an API to allow users outside of oom_kill.c to mark a victim and
wake up oom_reaper thread for expedited memory reclaim of the process being
killed.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
 include/linux/oom.h |  1 +
 mm/oom_kill.c       | 15 +++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/include/linux/oom.h b/include/linux/oom.h
index d07992009265..6c043c7518c1 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -112,6 +112,7 @@ extern unsigned long oom_badness(struct task_struct *p,
 		unsigned long totalpages);
 
 extern bool out_of_memory(struct oom_control *oc);
+extern bool expedite_reclaim(struct task_struct *task);
 
 extern void exit_oom_victim(void);
 
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 3a2484884cfd..6449710c8a06 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -1102,6 +1102,21 @@ bool out_of_memory(struct oom_control *oc)
 	return !!oc->chosen;
 }
 
+bool expedite_reclaim(struct task_struct *task)
+{
+	bool res = false;
+
+	task_lock(task);
+	if (task_will_free_mem(task)) {
+		mark_oom_victim(task);
+		wake_oom_reaper(task);
+		res = true;
+	}
+	task_unlock(task);
+
+	return res;
+}
+
 /*
  * The pagefault handler calls here because it is out of memory, so kill a
  * memory-hogging task. If oom_lock is held by somebody else, a parallel oom
-- 
2.21.0.392.gf8f6787159e-goog