Index: linux-2.6.20-rc3/include/linux/hugetlb.h
===================================================================
--- linux-2.6.20-rc3.orig/include/linux/hugetlb.h	2006-12-31 18:53:20.000000000 -0600
+++ linux-2.6.20-rc3/include/linux/hugetlb.h	2007-01-05 15:29:02.786446291 -0600
@@ -93,6 +93,9 @@ pte_t huge_ptep_get_and_clear(struct mm_
 void hugetlb_prefault_arch_hook(struct mm_struct *mm);
 #endif
 
+unsigned long global_huge_page_pages(void);
+unsigned long node_huge_page_pages(int node);
+
 #else /* !CONFIG_HUGETLB_PAGE */
 
 static inline int is_vm_hugetlb_page(struct vm_area_struct *vma)
@@ -125,6 +128,9 @@ static inline unsigned long hugetlb_tota
 #define HPAGE_SIZE	PAGE_SIZE
 #endif
 
+#define global_huge_page_pages		0
+#define node_huge_page_pages(__n)	0
+
 #endif /* !CONFIG_HUGETLB_PAGE */
 
 #ifdef CONFIG_HUGETLBFS
Index: linux-2.6.20-rc3/mm/hugetlb.c
===================================================================
--- linux-2.6.20-rc3.orig/mm/hugetlb.c	2006-12-31 18:53:20.000000000 -0600
+++ linux-2.6.20-rc3/mm/hugetlb.c	2007-01-05 15:31:00.369876250 -0600
@@ -27,6 +27,17 @@ unsigned long max_huge_pages;
 static struct list_head hugepage_freelists[MAX_NUMNODES];
 static unsigned int nr_huge_pages_node[MAX_NUMNODES];
 static unsigned int free_huge_pages_node[MAX_NUMNODES];
+
+unsigned long global_huge_page_pages(void)
+{
+	return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE);
+}
+
+unsigned long node_huge_page_pages(int node)
+{
+	return nr_huge_pages_node[node] * (HPAGE_SIZE / PAGE_SIZE);
+}
+
 /*
  * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
  */
Index: linux-2.6.20-rc3/mm/page-writeback.c
===================================================================
--- linux-2.6.20-rc3.orig/mm/page-writeback.c	2007-01-05 14:51:00.000000000 -0600
+++ linux-2.6.20-rc3/mm/page-writeback.c	2007-01-05 18:49:48.192187815 -0600
@@ -34,6 +34,7 @@
 #include <linux/buffer_head.h>
 #include <linux/pagevec.h>
 #include <linux/cpuset.h>
+#include <linux/hugetlb.h>
 
 /*
  * The maximum number of pages to writeout in a single bdflush/kupdate
@@ -160,12 +161,15 @@ get_dirty_limits(struct dirty_limits *dl
 			dl->nr_dirty += node_page_state(node, NR_FILE_DIRTY);
 			dl->nr_unstable += node_page_state(node, NR_UNSTABLE_NFS);
 			dl->nr_writeback += node_page_state(node, NR_WRITEBACK);
-			available_memory += NODE_DATA(node)->node_present_pages;
+			available_memory += NODE_DATA(node)->node_present_pages
+					- node_huge_page_pages(node)
+					- node_page_state(node, NR_SLAB_UNRECLAIMABLE);
 #ifdef CONFIG_HIGHMEM
 			high_memory += NODE_DATA(node)->node_zones[ZONE_HIGHMEM]->present_pages;
 #endif
 			nr_mapped += node_page_state(node, NR_FILE_MAPPED) +
 					node_page_state(node, NR_ANON_PAGES);
+
 		}
 	} else
 #endif
@@ -174,7 +178,9 @@ get_dirty_limits(struct dirty_limits *dl
 		dl->nr_dirty = global_page_state(NR_FILE_DIRTY);
 		dl->nr_unstable = global_page_state(NR_UNSTABLE_NFS);
 		dl->nr_writeback = global_page_state(NR_WRITEBACK);
-		available_memory = vm_total_pages;
+		available_memory = vm_total_pages
+				- global_huge_page_pages()
+				- global_page_state(NR_SLAB_UNRECLAIMABLE);
 		high_memory = totalhigh_pages;
 		nr_mapped = global_page_state(NR_FILE_MAPPED) +
 				global_page_state(NR_ANON_PAGES);
@@ -188,8 +194,12 @@ get_dirty_limits(struct dirty_limits *dl
 		available_memory -= high_memory;
 #endif
 
+	/*
+	 * We should subtract the amount of mlocked pages but we do not have
+	 * any way to account for it.
+	 */
 
-	unmapped_ratio = 100 - (nr_mapped * 100) / vm_total_pages;
+	unmapped_ratio = 100 - (nr_mapped * 100) / available_memory;
 
 	dirty_ratio = vm_dirty_ratio;
 	if (dirty_ratio > unmapped_ratio / 2)