1 files changed, 26 insertions, 0 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a61706193c31..f46b8615de6c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -781,6 +781,32 @@ void mem_cgroup_end_migration(struct page *newpage)
 }
 
 /*
+ * A call to try to shrink memory usage under specified resource controller.
+ * This is typically used for page reclaiming for shmem for reducing side
+ * effect of page allocation from shmem, which is used by some mem_cgroup.
+ */
+int mem_cgroup_shrink_usage(struct mm_struct *mm, gfp_t gfp_mask)
+{
+        struct mem_cgroup *mem;
+        int progress = 0;
+        int retry = MEM_CGROUP_RECLAIM_RETRIES;
+
+        rcu_read_lock();
+        mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
+        css_get(&mem->css);
+        rcu_read_unlock();
+
+        do {
+                progress = try_to_free_mem_cgroup_pages(mem, gfp_mask);
+        } while (!progress && --retry);
+
+        css_put(&mem->css);
+        if (!retry)
+                return -ENOMEM;
+        return 0;
+}
+
+/*
  * This routine traverse page_cgroup in given list and drop them all.
  * *And* this routine doesn't reclaim page itself, just removes page_cgroup.
  */