memcg: remove mem_cgroup_try_charge

After previous patch, mem_cgroup_try_charge is not used by anyone, so we
can remove it.

Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/memcontrol.h

@@ -40,8 +40,6 @@ struct mm_struct;
 extern int mem_cgroup_newpage_charge(struct page *page, struct mm_struct *mm,
 				gfp_t gfp_mask);
 /* for swap handling */
-extern int mem_cgroup_try_charge(struct mm_struct *mm,
-		gfp_t gfp_mask, struct mem_cgroup **ptr);
 extern int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
 		struct page *page, gfp_t mask, struct mem_cgroup **ptr);
 extern void mem_cgroup_commit_charge_swapin(struct page *page,
@@ -134,12 +132,6 @@ static inline int mem_cgroup_cache_charge(struct page *page,
 	return 0;
 }
 
-static inline int mem_cgroup_try_charge(struct mm_struct *mm,
-			gfp_t gfp_mask, struct mem_cgroup **ptr)
-{
-	return 0;
-}
-
 static inline int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
 		struct page *page, gfp_t gfp_mask, struct mem_cgroup **ptr)
 {

mm/memcontrol.c

@@ -839,27 +839,8 @@ nomem:
 	return -ENOMEM;
 }
 
-/**
- * mem_cgroup_try_charge - get charge of PAGE_SIZE.
- * @mm: an mm_struct which is charged against. (when *memcg is NULL)
- * @gfp_mask: gfp_mask for reclaim.
- * @memcg: a pointer to memory cgroup which is charged against.
- *
- * charge against memory cgroup pointed by *memcg. if *memcg == NULL, estimated
- * memory cgroup from @mm is got and stored in *memcg.
- *
- * Returns 0 if success. -ENOMEM at failure.
- * This call can invoke OOM-Killer.
- */
-
-int mem_cgroup_try_charge(struct mm_struct *mm,
-			  gfp_t mask, struct mem_cgroup **memcg)
-{
-	return __mem_cgroup_try_charge(mm, mask, memcg, true);
-}
-
 /*
- * commit a charge got by mem_cgroup_try_charge() and makes page_cgroup to be
+ * commit a charge got by __mem_cgroup_try_charge() and makes page_cgroup to be
  * USED state. If already USED, uncharge and return.
  */