memcg: page_cache_release not __free_page

There's nothing wrong with mem_cgroup_charge failure in do_wp_page and
do_anonymous page using __free_page, but it does look odd when nearby code
uses page_cache_release: use that instead (while turning a blind eye to
ancient inconsistencies of page_cache_release versus put_page).
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Cc: David Rientjes <rientjes@google.com>
Acked-by: NBalbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hirokazu Takahashi <taka@valinux.co.jp>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Cc: Paul Menage <menage@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/memory.c

@@ -1711,7 +1711,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	}
 	return ret;
 oom_free_new:
-	__free_page(new_page);
+	page_cache_release(new_page);
 oom:
 	if (old_page)
 		page_cache_release(old_page);
@@ -2163,7 +2163,7 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	page_cache_release(page);
 	goto unlock;
 oom_free_page:
-	__free_page(page);
+	page_cache_release(page);
 oom:
 	return VM_FAULT_OOM;
 }