[PATCH] vmscan: fix calculation of number of pages scanned

From: Nick Piggin <piggin@cyberone.com.au>

The logic which calculates the numberof pages which were scanned is mucked
up.  Fix.

diff --git a/mm/vmscan.c b/mm/vmscan.c
index c3cbe8db95e25742a54a7d52d392b02813f7fa0a..375d2bbf4cd19611ab01346cb29720b82d914d6b 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -244,8 +244,7 @@ static void handle_write_error(struct address_space *mapping,
  * shrink_list returns the number of reclaimed pages
  */
 static int
-shrink_list(struct list_head *page_list, unsigned int gfp_mask,
-               int *max_scan, int *nr_mapped)
+shrink_list(struct list_head *page_list, unsigned int gfp_mask, int *nr_scanned)
 {
        struct address_space *mapping;
        LIST_HEAD(ret_pages);
@@ -269,7 +268,7 @@ shrink_list(struct list_head *page_list, unsigned int gfp_mask,
 
                /* Double the slab pressure for mapped and swapcache pages */
                if (page_mapped(page) || PageSwapCache(page))
-                       (*nr_mapped)++;
+                       (*nr_scanned)++;
 
                BUG_ON(PageActive(page));
 
@@ -477,7 +476,7 @@ keep:
  */
 static int
 shrink_cache(const int nr_pages, struct zone *zone,
-               unsigned int gfp_mask, int max_scan, int *nr_mapped)
+               unsigned int gfp_mask, int max_scan, int *total_scanned)
 {
        LIST_HEAD(page_list);
        struct pagevec pvec;
@@ -534,8 +533,8 @@ shrink_cache(const int nr_pages, struct zone *zone,
                        mod_page_state_zone(zone, pgscan_kswapd, nr_scan);
                else
                        mod_page_state_zone(zone, pgscan_direct, nr_scan);
-               nr_freed = shrink_list(&page_list, gfp_mask,
-                                       &max_scan, nr_mapped);
+               nr_freed = shrink_list(&page_list, gfp_mask, total_scanned);
+               *total_scanned += nr_taken;
                if (current_is_kswapd())
                        mod_page_state(kswapd_steal, nr_freed);
                mod_page_state_zone(zone, pgsteal, nr_freed);
@@ -749,7 +748,7 @@ refill_inactive_zone(struct zone *zone, const int nr_pages_in,
  */
 static int
 shrink_zone(struct zone *zone, int max_scan, unsigned int gfp_mask,
-       const int nr_pages, int *nr_mapped, struct page_state *ps)
+       const int nr_pages, int *total_scanned, struct page_state *ps)
 {
        unsigned long ratio;
 
@@ -782,7 +781,7 @@ shrink_zone(struct zone *zone, int max_scan, unsigned int gfp_mask,
                refill_inactive_zone(zone, count, ps);
        }
        return shrink_cache(nr_pages, zone, gfp_mask,
-                               max_scan, nr_mapped);
+                               max_scan, total_scanned);
 }
 
 /*
@@ -811,7 +810,6 @@ shrink_caches(struct zone **zones, int priority, int *total_scanned,
        for (i = 0; zones[i] != NULL; i++) {
                int to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX);
                struct zone *zone = zones[i];
-               int nr_mapped = 0;
                int max_scan;
 
                if (zone->free_pages < zone->pages_high)
@@ -828,8 +826,7 @@ shrink_caches(struct zone **zones, int priority, int *total_scanned,
                if (max_scan < to_reclaim * 2)
                        max_scan = to_reclaim * 2;
                ret += shrink_zone(zone, max_scan, gfp_mask,
-                               to_reclaim, &nr_mapped, ps);
-               *total_scanned += max_scan + nr_mapped;
+                               to_reclaim, total_scanned, ps);
                if (ret >= nr_pages)
                        break;
        }
@@ -944,7 +941,7 @@ static int balance_pgdat(pg_data_t *pgdat, int nr_pages, struct page_state *ps)
 
                for (i = 0; i < pgdat->nr_zones; i++) {
                        struct zone *zone = pgdat->node_zones + i;
-                       int nr_mapped = 0;
+                       int total_scanned = 0;
                        int max_scan;
                        int to_reclaim;
                        int reclaimed;
@@ -966,10 +963,10 @@ static int balance_pgdat(pg_data_t *pgdat, int nr_pages, struct page_state *ps)
                        if (max_scan < SWAP_CLUSTER_MAX)
                                max_scan = SWAP_CLUSTER_MAX;
                        reclaimed = shrink_zone(zone, max_scan, GFP_KERNEL,
-                                       to_reclaim, &nr_mapped, ps);
+                                       to_reclaim, &total_scanned, ps);
                        if (i < ZONE_HIGHMEM) {
                                reclaim_state->reclaimed_slab = 0;
-                               shrink_slab(max_scan + nr_mapped, GFP_KERNEL);
+                               shrink_slab(total_scanned, GFP_KERNEL);
                                reclaimed += reclaim_state->reclaimed_slab;
                        }
                        to_free -= reclaimed;