mm, page_alloc: fix dirtyable highmem calculation

[karo-tx-linux.git] / mm / page-writeback.c

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 0bca2376bd42831ebb23b0f084dcbcb16e601d99..573d138fa7a592e5ff2637d1636ec0c87b00585e 100644 (file)
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -307,27 +307,31 @@ static unsigned long highmem_dirtyable_memory(unsigned long total)
 {
 #ifdef CONFIG_HIGHMEM
        int node;
-       unsigned long x = 0;
+       unsigned long x;
        int i;
-       unsigned long dirtyable = atomic_read(&highmem_file_pages);
+       unsigned long dirtyable = 0;
 
        for_each_node_state(node, N_HIGH_MEMORY) {
                for (i = ZONE_NORMAL + 1; i < MAX_NR_ZONES; i++) {
                        struct zone *z;
+                       unsigned long nr_pages;
 
                        if (!is_highmem_idx(i))
                                continue;
 
                        z = &NODE_DATA(node)->node_zones[i];
-                       dirtyable += zone_page_state(z, NR_FREE_PAGES);
+                       if (!populated_zone(z))
+                               continue;
 
+                       nr_pages = zone_page_state(z, NR_FREE_PAGES);
                        /* watch for underflows */
-                       dirtyable -= min(dirtyable, high_wmark_pages(z));
-
-                       x += dirtyable;
+                       nr_pages -= min(nr_pages, high_wmark_pages(z));
+                       dirtyable += nr_pages;
                }
        }
 
+       x = dirtyable + atomic_read(&highmem_file_pages);
+
        /*
         * Unreclaimable memory (kernel memory or anonymous memory
         * without swap) can bring down the dirtyable pages below