memcg: don't uncharge in mem_cgroup_move_account()

Now, all callers pass 'false' for 'bool uncharge' so remove this argument.
Signed-off-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ying Han <yinghan@google.com>
Cc: Glauber Costa <glommer@parallels.com>
Reviewed-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/memcontrol.c

@@ -2592,23 +2592,19 @@ void mem_cgroup_split_huge_fixup(struct page *head)
  * @pc:	page_cgroup of the page.
  * @from: mem_cgroup which the page is moved from.
  * @to:	mem_cgroup which the page is moved to. @from != @to.
- * @uncharge: whether we should call uncharge and css_put against @from.
  *
  * The caller must confirm following.
  * - page is not on LRU (isolate_page() is useful.)
  * - compound_lock is held when nr_pages > 1
  *
- * This function doesn't do "charge" nor css_get to new cgroup. It should be
- * done by a caller(__mem_cgroup_try_charge would be useful). If @uncharge is
- * true, this function does "uncharge" from old cgroup, but it doesn't if
- * @uncharge is false, so a caller should do "uncharge".
+ * This function doesn't do "charge" to new cgroup and doesn't do "uncharge"
+ * from old cgroup.
  */
 static int mem_cgroup_move_account(struct page *page,
 				   unsigned int nr_pages,
 				   struct page_cgroup *pc,
 				   struct mem_cgroup *from,
-				   struct mem_cgroup *to,
-				   bool uncharge)
+				   struct mem_cgroup *to)
 {
 	unsigned long flags;
 	int ret;
@@ -2642,9 +2638,6 @@ static int mem_cgroup_move_account(struct page *page,
 		preempt_enable();
 	}
 	mem_cgroup_charge_statistics(from, anon, -nr_pages);
-	if (uncharge)
-		/* This is not "cancel", but cancel_charge does all we need. */
-		__mem_cgroup_cancel_charge(from, nr_pages);
 
 	/* caller should have done css_get */
 	pc->mem_cgroup = to;
@@ -2706,7 +2699,7 @@ static int mem_cgroup_move_parent(struct page *page,
 		flags = compound_lock_irqsave(page);
 
 	ret = mem_cgroup_move_account(page, nr_pages,
-				pc, child, parent, false);
+				pc, child, parent);
 	if (!ret)
 		__mem_cgroup_cancel_local_charge(child, nr_pages);
 
@@ -5474,8 +5467,7 @@ static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
 			if (!isolate_lru_page(page)) {
 				pc = lookup_page_cgroup(page);
 				if (!mem_cgroup_move_account(page, HPAGE_PMD_NR,
-							     pc, mc.from, mc.to,
-							     false)) {
+							pc, mc.from, mc.to)) {
 					mc.precharge -= HPAGE_PMD_NR;
 					mc.moved_charge += HPAGE_PMD_NR;
 				}
@@ -5505,7 +5497,7 @@ static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
 				goto put;
 			pc = lookup_page_cgroup(page);
 			if (!mem_cgroup_move_account(page, 1, pc,
-						     mc.from, mc.to, false)) {
+						     mc.from, mc.to)) {
 				mc.precharge--;
 				/* we uncharge from mc.from later. */
 				mc.moved_charge++;