1 files changed, 43 insertions, 13 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5cbf64dd79c..ba4e87df3fc 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -579,6 +579,40 @@ redo:
         put_page(page);         /* drop ref from isolate */
 }
 
+enum page_references {
+        PAGEREF_RECLAIM,
+        PAGEREF_RECLAIM_CLEAN,
+        PAGEREF_ACTIVATE,
+};
+
+static enum page_references page_check_references(struct page *page,
+                                                  struct scan_control *sc)
+{
+        unsigned long vm_flags;
+        int referenced;
+
+        referenced = page_referenced(page, 1, sc->mem_cgroup, &vm_flags);
+        if (!referenced)
+                return PAGEREF_RECLAIM;
+
+        /* Lumpy reclaim - ignore references */
+        if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
+                return PAGEREF_RECLAIM;
+
+        /*
+         * Mlock lost the isolation race with us.  Let try_to_unmap()
+         * move the page to the unevictable list.
+         */
+        if (vm_flags & VM_LOCKED)
+                return PAGEREF_RECLAIM;
+
+        if (page_mapping_inuse(page))
+                return PAGEREF_ACTIVATE;
+
+        /* Reclaim if clean, defer dirty pages to writeback */
+        return PAGEREF_RECLAIM_CLEAN;
+}
+
 /*
  * shrink_page_list() returns the number of reclaimed pages
  */
@@ -590,16 +624,15 @@ static unsigned long shrink_page_list(struct list_head *page_list,
         struct pagevec freed_pvec;
         int pgactivate = 0;
         unsigned long nr_reclaimed = 0;
-        unsigned long vm_flags;
 
         cond_resched();
 
         pagevec_init(&freed_pvec, 1);
         while (!list_empty(page_list)) {
+                enum page_references references;
                 struct address_space *mapping;
                 struct page *page;
                 int may_enter_fs;
-                int referenced;
 
                 cond_resched();
 
@@ -641,17 +674,14 @@ static unsigned long shrink_page_list(struct list_head *page_list,
                                 goto keep_locked;
                 }
 
-                referenced = page_referenced(page, 1,
-                                                sc->mem_cgroup, &vm_flags);
-                /*
-                 * In active use or really unfreeable?  Activate it.
-                 * If page which have PG_mlocked lost isoltation race,
-                 * try_to_unmap moves it to unevictable list
-                 */
-                if (sc->order <= PAGE_ALLOC_COSTLY_ORDER &&
-                                        referenced && page_mapping_inuse(page)
-                                        && !(vm_flags & VM_LOCKED))
+                references = page_check_references(page, sc);
+                switch (references) {
+                case PAGEREF_ACTIVATE:
                         goto activate_locked;
+                case PAGEREF_RECLAIM:
+                case PAGEREF_RECLAIM_CLEAN:
+                        ; /* try to reclaim the page below */
+                }
 
                 /*
                  * Anonymous process memory has backing store?
@@ -685,7 +715,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
                 }
 
                 if (PageDirty(page)) {
-                        if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && referenced)
+                        if (references == PAGEREF_RECLAIM_CLEAN)
                                 goto keep_locked;
                         if (!may_enter_fs)
                                 goto keep_locked;