[RFC][PATCH v2 1/8] Replace page_mapping_inuse() with page_mapped()

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

page reclaim logic need to distingish mapped and unmapped pages.
However page_mapping_inuse() don't provide proper test way. it test
the address space (i.e. file) is mmpad(). Why `page' reclaim need
care unrelated page's mapped state? it's unrelated.

Thus, This patch replace page_mapping_inuse() with page_mapped()

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
---
 mm/vmscan.c |   25 ++-----------------------
 1 files changed, 2 insertions(+), 23 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2bbee91..3366bec 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -262,27 +262,6 @@ unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
 	return ret;
 }
 
-/* Called without lock on whether page is mapped, so answer is unstable */
-static inline int page_mapping_inuse(struct page *page)
-{
-	struct address_space *mapping;
-
-	/* Page is in somebody's page tables. */
-	if (page_mapped(page))
-		return 1;
-
-	/* Be more reluctant to reclaim swapcache than pagecache */
-	if (PageSwapCache(page))
-		return 1;
-
-	mapping = page_mapping(page);
-	if (!mapping)
-		return 0;
-
-	/* File is mmap'd by somebody? */
-	return mapping_mapped(mapping);
-}
-
 static inline int is_page_cache_freeable(struct page *page)
 {
 	/*
@@ -649,7 +628,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		 * try_to_unmap moves it to unevictable list
 		 */
 		if (sc->order <= PAGE_ALLOC_COSTLY_ORDER &&
-					referenced && page_mapping_inuse(page)
+					referenced && page_mapped(page)
 					&& !(vm_flags & VM_LOCKED))
 			goto activate_locked;
 
@@ -1351,7 +1330,7 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
 		}
 
 		/* page_referenced clears PageReferenced */
-		if (page_mapping_inuse(page) &&
+		if (page_mapped(page) &&
 		    page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) {
 			nr_rotated++;
 			/*
-- 
1.6.5.2



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