[PATCH] drivers/video/sis/initextlfb.c: removal of old code

[pandora-kernel.git] / mm / vmscan.c

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 089e943..eca7031 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -19,6 +19,7 @@
 #include <linux/pagemap.h>
 #include <linux/init.h>
 #include <linux/highmem.h>
+#include <linux/vmstat.h>
 #include <linux/file.h>
 #include <linux/writeback.h>
 #include <linux/blkdev.h>
@@ -370,7 +371,7 @@ static pageout_t pageout(struct page *page, struct address_space *mapping)
                        /* synchronous write or broken a_ops? */
                        ClearPageReclaim(page);
                }
-
+               inc_zone_page_state(page, NR_VMSCAN_WRITE);
                return PAGE_SUCCESS;
        }
 
@@ -383,11 +384,30 @@ int remove_mapping(struct address_space *mapping, struct page *page)
        BUG_ON(mapping != page_mapping(page));
 
        write_lock_irq(&mapping->tree_lock);
-
        /*
-        * The non-racy check for busy page.  It is critical to check
-        * PageDirty _after_ making sure that the page is freeable and
-        * not in use by anybody.       (pagecache + us == 2)
+        * The non racy check for a busy page.
+        *
+        * Must be careful with the order of the tests. When someone has
+        * a ref to the page, it may be possible that they dirty it then
+        * drop the reference. So if PageDirty is tested before page_count
+        * here, then the following race may occur:
+        *
+        * get_user_pages(&page);
+        * [user mapping goes away]
+        * write_to(page);
+        *                              !PageDirty(page)    [good]
+        * SetPageDirty(page);
+        * put_page(page);
+        *                              !page_count(page)   [good, discard it]
+        *
+        * [oops, our write_to data is lost]
+        *
+        * Reversing the order of the tests ensures such a situation cannot
+        * escape unnoticed. The smp_rmb is needed to ensure the page->flags
+        * load is not satisfied before that of page->_count.
+        *
+        * Note that if SetPageDirty is always performed via set_page_dirty,
+        * and thus under tree_lock, then this ordering is not required.
         */
        if (unlikely(page_count(page) != 2))
                goto cannot_free;
@@ -1566,6 +1586,7 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
                .gfp_mask = gfp_mask,
                .swappiness = vm_swappiness,
        };
+       unsigned long slab_reclaimable;
 
        disable_swap_token();
        cond_resched();
@@ -1592,7 +1613,8 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
                } while (priority >= 0 && nr_reclaimed < nr_pages);
        }
 
-       if (zone_page_state(zone, NR_SLAB_RECLAIMABLE) > zone->min_slab_pages) {
+       slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
+       if (slab_reclaimable > zone->min_slab_pages) {
                /*
                 * shrink_slab() does not currently allow us to determine how
                 * many pages were freed in this zone. So we take the current
@@ -1603,12 +1625,17 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
                 * Note that shrink_slab will free memory on all zones and may
                 * take a long time.
                 */
-               unsigned long limit = zone_page_state(zone,
-                               NR_SLAB_RECLAIMABLE) - nr_pages;
-
                while (shrink_slab(sc.nr_scanned, gfp_mask, order) &&
-                       zone_page_state(zone, NR_SLAB_RECLAIMABLE) > limit)
+                       zone_page_state(zone, NR_SLAB_RECLAIMABLE) >
+                               slab_reclaimable - nr_pages)
                        ;
+
+               /*
+                * Update nr_reclaimed by the number of slab pages we
+                * reclaimed from this zone.
+                */
+               nr_reclaimed += slab_reclaimable -
+                       zone_page_state(zone, NR_SLAB_RECLAIMABLE);
        }
 
        p->reclaim_state = NULL;
@@ -1654,7 +1681,7 @@ int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
         * over remote processors and spread off node memory allocations
         * as wide as possible.
         */
-       node_id = zone->zone_pgdat->node_id;
+       node_id = zone_to_nid(zone);
        mask = node_to_cpumask(node_id);
        if (!cpus_empty(mask) && node_id != numa_node_id())
                return 0;