3 files changed, 63 insertions, 2 deletions

diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c
index 47928399e38a..3e16fe08150e 100644
--- a/arch/x86_64/mm/init.c
+++ b/arch/x86_64/mm/init.c
@@ -655,8 +655,10 @@ void __init reserve_bootmem_generic(unsigned long phys, unsigned len)
 #else                   
         reserve_bootmem(phys, len);    
 #endif
-        if (phys+len <= MAX_DMA_PFN*PAGE_SIZE)
+        if (phys+len <= MAX_DMA_PFN*PAGE_SIZE) {
                 dma_reserve += len / PAGE_SIZE;
+                set_dma_reserve(dma_reserve);
+        }
 }
 
 int kern_addr_valid(unsigned long addr) 
diff --git a/include/linux/mm.h b/include/linux/mm.h
index c0402da7cce0..22936e1fcdf2 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -984,6 +984,7 @@ extern void sparse_memory_present_with_active_regions(int nid);
 extern int early_pfn_to_nid(unsigned long pfn);
 #endif /* CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID */
 #endif /* CONFIG_ARCH_POPULATES_NODE_MAP */
+extern void set_dma_reserve(unsigned long new_dma_reserve);
 extern void memmap_init_zone(unsigned long, int, unsigned long, unsigned long);
 extern void setup_per_zone_pages_min(void);
 extern void mem_init(void);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 26c9939857fa..8d9a1eb9fbba 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -104,6 +104,7 @@ int min_free_kbytes = 1024;
 
 unsigned long __meminitdata nr_kernel_pages;
 unsigned long __meminitdata nr_all_pages;
+static unsigned long __initdata dma_reserve;
 
 #ifdef CONFIG_ARCH_POPULATES_NODE_MAP
   /*
@@ -2213,6 +2214,20 @@ unsigned long __init zone_absent_pages_in_node(int nid,
                                 arch_zone_lowest_possible_pfn[zone_type],
                                 arch_zone_highest_possible_pfn[zone_type]);
 }
+
+/* Return the zone index a PFN is in */
+int memmap_zone_idx(struct page *lmem_map)
+{
+        int i;
+        unsigned long phys_addr = virt_to_phys(lmem_map);
+        unsigned long pfn = phys_addr >> PAGE_SHIFT;
+
+        for (i = 0; i < MAX_NR_ZONES; i++)
+                if (pfn < arch_zone_highest_possible_pfn[i])
+                        break;
+
+        return i;
+}
 #else
 static inline unsigned long zone_spanned_pages_in_node(int nid,
                                         unsigned long zone_type,
@@ -2230,6 +2245,11 @@ static inline unsigned long zone_absent_pages_in_node(int nid,
 
         return zholes_size[zone_type];
 }
+
+static inline int memmap_zone_idx(struct page *lmem_map)
+{
+        return MAX_NR_ZONES;
+}
 #endif
 
 static void __init calculate_node_totalpages(struct pglist_data *pgdat,
@@ -2274,12 +2294,35 @@ static void __meminit free_area_init_core(struct pglist_data *pgdat,
         
         for (j = 0; j < MAX_NR_ZONES; j++) {
                 struct zone *zone = pgdat->node_zones + j;
-                unsigned long size, realsize;
+                unsigned long size, realsize, memmap_pages;
 
                 size = zone_spanned_pages_in_node(nid, j, zones_size);
                 realsize = size - zone_absent_pages_in_node(nid, j,
                                                                 zholes_size);
 
+                /*
+                 * Adjust realsize so that it accounts for how much memory
+                 * is used by this zone for memmap. This affects the watermark
+                 * and per-cpu initialisations
+                 */
+                memmap_pages = (size * sizeof(struct page)) >> PAGE_SHIFT;
+                if (realsize >= memmap_pages) {
+                        realsize -= memmap_pages;
+                        printk(KERN_DEBUG
+                                "  %s zone: %lu pages used for memmap\n",
+                                zone_names[j], memmap_pages);
+                } else
+                        printk(KERN_WARNING
+                                "  %s zone: %lu pages exceeds realsize %lu\n",
+                                zone_names[j], memmap_pages, realsize);
+
+                /* Account for reserved DMA pages */
+                if (j == ZONE_DMA && realsize > dma_reserve) {
+                        realsize -= dma_reserve;
+                        printk(KERN_DEBUG "  DMA zone: %lu pages reserved\n",
+                                                                dma_reserve);
+                }
+
                 if (!is_highmem_idx(j))
                         nr_kernel_pages += realsize;
                 nr_all_pages += realsize;
@@ -2596,6 +2639,21 @@ void __init free_area_init_nodes(unsigned long *max_zone_pfn)
 }
 #endif /* CONFIG_ARCH_POPULATES_NODE_MAP */
 
+/**
+ * set_dma_reserve - Account the specified number of pages reserved in ZONE_DMA
+ * @new_dma_reserve - The number of pages to mark reserved
+ *
+ * The per-cpu batchsize and zone watermarks are determined by present_pages.
+ * In the DMA zone, a significant percentage may be consumed by kernel image
+ * and other unfreeable allocations which can skew the watermarks badly. This
+ * function may optionally be used to account for unfreeable pages in
+ * ZONE_DMA. The effect will be lower watermarks and smaller per-cpu batchsize
+ */
+void __init set_dma_reserve(unsigned long new_dma_reserve)
+{
+        dma_reserve = new_dma_reserve;
+}
+
 #ifndef CONFIG_NEED_MULTIPLE_NODES
 static bootmem_data_t contig_bootmem_data;
 struct pglist_data contig_page_data = { .bdata = &contig_bootmem_data };