8 files changed, 106 insertions, 44 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 3b337efbe533..66560f1a0564 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -19,6 +19,7 @@
 #include <linux/bit_spinlock.h>
 #include <linux/shrinker.h>
 #include <linux/resource.h>
+#include <linux/page_ext.h>
 
 struct mempolicy;
 struct anon_vma;
@@ -2155,20 +2156,36 @@ extern void copy_user_huge_page(struct page *dst, struct page *src,
                                 unsigned int pages_per_huge_page);
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
 
+extern struct page_ext_operations debug_guardpage_ops;
+extern struct page_ext_operations page_poisoning_ops;
+
 #ifdef CONFIG_DEBUG_PAGEALLOC
 extern unsigned int _debug_guardpage_minorder;
+extern bool _debug_guardpage_enabled;
 
 static inline unsigned int debug_guardpage_minorder(void)
 {
         return _debug_guardpage_minorder;
 }
 
+static inline bool debug_guardpage_enabled(void)
+{
+        return _debug_guardpage_enabled;
+}
+
 static inline bool page_is_guard(struct page *page)
 {
-        return test_bit(PAGE_DEBUG_FLAG_GUARD, &page->debug_flags);
+        struct page_ext *page_ext;
+
+        if (!debug_guardpage_enabled())
+                return false;
+
+        page_ext = lookup_page_ext(page);
+        return test_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);
 }
 #else
 static inline unsigned int debug_guardpage_minorder(void) { return 0; }
+static inline bool debug_guardpage_enabled(void) { return false; }
 static inline bool page_is_guard(struct page *page) { return false; }
 #endif /* CONFIG_DEBUG_PAGEALLOC */
 
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index fc2daffa9db1..6d34aa266a8c 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -10,7 +10,6 @@
 #include <linux/rwsem.h>
 #include <linux/completion.h>
 #include <linux/cpumask.h>
-#include <linux/page-debug-flags.h>
 #include <linux/uprobes.h>
 #include <linux/page-flags-layout.h>
 #include <asm/page.h>
@@ -186,9 +185,6 @@ struct page {
         void *virtual;                  /* Kernel virtual address (NULL if
                                            not kmapped, ie. highmem) */
 #endif /* WANT_PAGE_VIRTUAL */
-#ifdef CONFIG_WANT_PAGE_DEBUG_FLAGS
-        unsigned long debug_flags;      /* Use atomic bitops on this */
-#endif
 
 #ifdef CONFIG_KMEMCHECK
         /*
diff --git a/include/linux/page-debug-flags.h b/include/linux/page-debug-flags.h
deleted file mode 100644
index 22691f614043..000000000000
--- a/include/linux/page-debug-flags.h
+++ /dev/null
@@ -1,32 +0,0 @@
-#ifndef LINUX_PAGE_DEBUG_FLAGS_H
-#define  LINUX_PAGE_DEBUG_FLAGS_H
-
-/*
- * page->debug_flags bits:
- *
- * PAGE_DEBUG_FLAG_POISON is set for poisoned pages. This is used to
- * implement generic debug pagealloc feature. The pages are filled with
- * poison patterns and set this flag after free_pages(). The poisoned
- * pages are verified whether the patterns are not corrupted and clear
- * the flag before alloc_pages().
- */
-
-enum page_debug_flags {
-        PAGE_DEBUG_FLAG_POISON,         /* Page is poisoned */
-        PAGE_DEBUG_FLAG_GUARD,
-};
-
-/*
- * Ensure that CONFIG_WANT_PAGE_DEBUG_FLAGS reliably
- * gets turned off when no debug features are enabling it!
- */
-
-#ifdef CONFIG_WANT_PAGE_DEBUG_FLAGS
-#if !defined(CONFIG_PAGE_POISONING) && \
-    !defined(CONFIG_PAGE_GUARD) \
-/* && !defined(CONFIG_PAGE_DEBUG_SOMETHING_ELSE) && ... */
-#error WANT_PAGE_DEBUG_FLAGS is turned on with no debug features!
-#endif
-#endif /* CONFIG_WANT_PAGE_DEBUG_FLAGS */
-
-#endif /* LINUX_PAGE_DEBUG_FLAGS_H */
diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h
index 2ccc8b414e5c..61c0f05f9069 100644
--- a/include/linux/page_ext.h
+++ b/include/linux/page_ext.h
@@ -10,6 +10,21 @@ struct page_ext_operations {
 #ifdef CONFIG_PAGE_EXTENSION
 
 /*
+ * page_ext->flags bits:
+ *
+ * PAGE_EXT_DEBUG_POISON is set for poisoned pages. This is used to
+ * implement generic debug pagealloc feature. The pages are filled with
+ * poison patterns and set this flag after free_pages(). The poisoned
+ * pages are verified whether the patterns are not corrupted and clear
+ * the flag before alloc_pages().
+ */
+
+enum page_ext_flags {
+        PAGE_EXT_DEBUG_POISON,          /* Page is poisoned */
+        PAGE_EXT_DEBUG_GUARD,
+};
+
+/*
  * Page Extension can be considered as an extended mem_map.
  * A page_ext page is associated with every page descriptor. The
  * page_ext helps us add more information about the page.
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index 1ba81c7769f7..56badfc4810a 100644
--- a/mm/Kconfig.debug
+++ b/mm/Kconfig.debug
@@ -12,6 +12,7 @@ config DEBUG_PAGEALLOC
         depends on DEBUG_KERNEL
         depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC
         depends on !KMEMCHECK
+        select PAGE_EXTENSION
         select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC
         select PAGE_GUARD if ARCH_SUPPORTS_DEBUG_PAGEALLOC
         ---help---
diff --git a/mm/debug-pagealloc.c b/mm/debug-pagealloc.c
index 789ff70c8a4a..0072f2c53331 100644
--- a/mm/debug-pagealloc.c
+++ b/mm/debug-pagealloc.c
@@ -2,23 +2,49 @@
 #include <linux/string.h>
 #include <linux/mm.h>
 #include <linux/highmem.h>
-#include <linux/page-debug-flags.h>
+#include <linux/page_ext.h>
 #include <linux/poison.h>
 #include <linux/ratelimit.h>
 
+static bool page_poisoning_enabled __read_mostly;
+
+static bool need_page_poisoning(void)
+{
+        return true;
+}
+
+static void init_page_poisoning(void)
+{
+        page_poisoning_enabled = true;
+}
+
+struct page_ext_operations page_poisoning_ops = {
+        .need = need_page_poisoning,
+        .init = init_page_poisoning,
+};
+
 static inline void set_page_poison(struct page *page)
 {
-        __set_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
+        struct page_ext *page_ext;
+
+        page_ext = lookup_page_ext(page);
+        __set_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
 }
 
 static inline void clear_page_poison(struct page *page)
 {
-        __clear_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
+        struct page_ext *page_ext;
+
+        page_ext = lookup_page_ext(page);
+        __clear_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
 }
 
 static inline bool page_poison(struct page *page)
 {
-        return test_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
+        struct page_ext *page_ext;
+
+        page_ext = lookup_page_ext(page);
+        return test_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
 }
 
 static void poison_page(struct page *page)
@@ -95,6 +121,9 @@ static void unpoison_pages(struct page *page, int n)
 
 void kernel_map_pages(struct page *page, int numpages, int enable)
 {
+        if (!page_poisoning_enabled)
+                return;
+
         if (enable)
                 unpoison_pages(page, numpages);
         else
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b64666cf5865..e0a39d328ca1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -56,7 +56,7 @@
 #include <linux/prefetch.h>
 #include <linux/mm_inline.h>
 #include <linux/migrate.h>
-#include <linux/page-debug-flags.h>
+#include <linux/page_ext.h>
 #include <linux/hugetlb.h>
 #include <linux/sched/rt.h>
 
@@ -425,6 +425,22 @@ static inline void prep_zero_page(struct page *page, unsigned int order,
 
 #ifdef CONFIG_DEBUG_PAGEALLOC
 unsigned int _debug_guardpage_minorder;
+bool _debug_guardpage_enabled __read_mostly;
+
+static bool need_debug_guardpage(void)
+{
+        return true;
+}
+
+static void init_debug_guardpage(void)
+{
+        _debug_guardpage_enabled = true;
+}
+
+struct page_ext_operations debug_guardpage_ops = {
+        .need = need_debug_guardpage,
+        .init = init_debug_guardpage,
+};
 
 static int __init debug_guardpage_minorder_setup(char *buf)
 {
@@ -443,7 +459,14 @@ __setup("debug_guardpage_minorder=", debug_guardpage_minorder_setup);
 static inline void set_page_guard(struct zone *zone, struct page *page,
                                 unsigned int order, int migratetype)
 {
-        __set_bit(PAGE_DEBUG_FLAG_GUARD, &page->debug_flags);
+        struct page_ext *page_ext;
+
+        if (!debug_guardpage_enabled())
+                return;
+
+        page_ext = lookup_page_ext(page);
+        __set_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);
+
         INIT_LIST_HEAD(&page->lru);
         set_page_private(page, order);
         /* Guard pages are not available for any usage */
@@ -453,12 +476,20 @@ static inline void set_page_guard(struct zone *zone, struct page *page,
 static inline void clear_page_guard(struct zone *zone, struct page *page,
                                 unsigned int order, int migratetype)
 {
-        __clear_bit(PAGE_DEBUG_FLAG_GUARD, &page->debug_flags);
+        struct page_ext *page_ext;
+
+        if (!debug_guardpage_enabled())
+                return;
+
+        page_ext = lookup_page_ext(page);
+        __clear_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);
+
         set_page_private(page, 0);
         if (!is_migrate_isolate(migratetype))
                 __mod_zone_freepage_state(zone, (1 << order), migratetype);
 }
 #else
+struct page_ext_operations debug_guardpage_ops = { NULL, };
 static inline void set_page_guard(struct zone *zone, struct page *page,
                                 unsigned int order, int migratetype) {}
 static inline void clear_page_guard(struct zone *zone, struct page *page,
@@ -869,6 +900,7 @@ static inline void expand(struct zone *zone, struct page *page,
                 VM_BUG_ON_PAGE(bad_range(zone, &page[size]), &page[size]);
 
                 if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC) &&
+                        debug_guardpage_enabled() &&
                         high < debug_guardpage_minorder()) {
                         /*
                          * Mark as guard pages (or page), that will allow to
diff --git a/mm/page_ext.c b/mm/page_ext.c
index 514a3bccd63f..c2cd7b15f0de 100644
--- a/mm/page_ext.c
+++ b/mm/page_ext.c
@@ -51,6 +51,10 @@
  */
 
 static struct page_ext_operations *page_ext_ops[] = {
+        &debug_guardpage_ops,
+#ifdef CONFIG_PAGE_POISONING
+        &page_poisoning_ops,
+#endif
 };
 
 static unsigned long total_usage;