[PATCH] memcg: shmem_getpage release page sooner

[Hugh Dickins]

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@xxxxxxxxxxx>
---
Should follow mmotm's memcg-helper-function-for-relcaim-from-shmem.patch

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

--- mmotm/mm/shmem.c	2008-06-27 13:39:20.000000000 +0100
+++ linux/mm/shmem.c	2008-06-27 17:25:41.000000000 +0100
@@ -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) {
--
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