No big deal, but since mem_cgroup_shrink_usage doesn't require a page to
operate upon, page_cache_release the swappage before calling it, so it's
not pinned across the reclaim.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Cc: Paul Menage <menage@google.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/shmem.c |    8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff -puN mm/shmem.c~memcg-helper-function-for-relcaim-from-shmem-memcg-shmem_getpage-release-page-sooner mm/shmem.c
--- a/mm/shmem.c~memcg-helper-function-for-relcaim-from-shmem-memcg-shmem_getpage-release-page-sooner
+++ a/mm/shmem.c
@@ -1315,16 +1315,14 @@ repeat:
 			shmem_swp_unmap(entry);
 			spin_unlock(&info->lock);
 			unlock_page(swappage);
+			page_cache_release(swappage);
 			if (error == -ENOMEM) {
 				/* allow reclaim from this memory cgroup */
 				error = mem_cgroup_shrink_usage(current->mm,
-					gfp & ~__GFP_HIGHMEM);
-				if (error) {
-					page_cache_release(swappage);
+								gfp);
+				if (error)
 					goto failed;
-				}
 			}
-			page_cache_release(swappage);
 			goto repeat;
 		}
 	} else if (sgp == SGP_READ && !filepage) {
_