Suspend 2 merge: 18/51: Debug page_alloc support.

[Nigel Cunningham]

This patch provides support for making suspend work when DEBUG_PAGEALLOC
is enabled.

diff -ruN 510-debug-pagealloc-support-old/arch/i386/mm/pageattr.c 510-debug-pagealloc-support-new/arch/i386/mm/pageattr.c
--- 510-debug-pagealloc-support-old/arch/i386/mm/pageattr.c	2004-11-03 21:53:39.000000000 +1100
+++ 510-debug-pagealloc-support-new/arch/i386/mm/pageattr.c	2004-11-04 16:27:40.000000000 +1100
@@ -211,5 +213,49 @@
 EXPORT_SYMBOL(kernel_map_pages);
 #endif
 
+#ifdef CONFIG_SOFTWARE_SUSPEND2
+#ifdef CONFIG_DEBUG_PAGEALLOC
+static int page_is_kernel_mapped(struct page * page)
+{
+	pte_t *kpte; 
+	unsigned long address;
+
+#ifdef CONFIG_HIGHMEM
+	if (page >= highmem_start_page) 
+		return 0;
+#endif
+
+	address = (unsigned long)page_address(page);
+	
+	kpte = lookup_address(address);
+	if (!kpte)
+		return 0;
+
+	if (pte_same(*kpte, mk_pte(page, PAGE_KERNEL)))
+		return 1;
+
+	return 0;
+}
+
+int suspend_map_kernel_page(struct page * page, int enable)
+{
+	int is_already_mapped = page_is_kernel_mapped(page);
+
+	if (enable == is_already_mapped)
+		return 1;
+
+	kernel_map_pages(page, 1, enable);
+
+	return 0;
+}
+#else
+int suspend_map_kernel_page(struct page * page, int enable)
+{
+	return (enable == 1);
+}
+#endif
+EXPORT_SYMBOL(suspend_map_kernel_page);
+#endif
+
 EXPORT_SYMBOL(change_page_attr);
 EXPORT_SYMBOL(global_flush_tlb);


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