kmemcheck: add hooks for the page allocator

This adds support for tracking the initializedness of memory that
was allocated with the page allocator. Highmem requests are not
tracked.

Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: NPekka Enberg <penberg@cs.helsinki.fi>

[build fix for !CONFIG_KMEMCHECK]
Signed-off-by: NIngo Molnar <mingo@elte.hu>

[rebased for mainline inclusion]
Signed-off-by: NVegard Nossum <vegard.nossum@gmail.com>

arch/x86/include/asm/thread_info.h

@@ -154,9 +154,9 @@ struct thread_info {
 
 /* thread information allocation */
 #ifdef CONFIG_DEBUG_STACK_USAGE
-#define THREAD_FLAGS (GFP_KERNEL | __GFP_ZERO)
+#define THREAD_FLAGS (GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO)
 #else
-#define THREAD_FLAGS GFP_KERNEL
+#define THREAD_FLAGS (GFP_KERNEL | __GFP_NOTRACK)
 #endif
 
 #define __HAVE_ARCH_THREAD_INFO_ALLOCATOR

arch/x86/mm/kmemcheck/shadow.c

@@ -116,6 +116,14 @@ void kmemcheck_mark_uninitialized_pages(struct page *p, unsigned int n)
 		kmemcheck_mark_uninitialized(page_address(&p[i]), PAGE_SIZE);
 }
 
+void kmemcheck_mark_initialized_pages(struct page *p, unsigned int n)
+{
+	unsigned int i;
+
+	for (i = 0; i < n; ++i)
+		kmemcheck_mark_initialized(page_address(&p[i]), PAGE_SIZE);
+}
+
 enum kmemcheck_shadow kmemcheck_shadow_test(void *shadow, unsigned int size)
 {
 	uint8_t *x;

include/linux/gfp.h

@@ -51,7 +51,12 @@ struct vm_area_struct;
 #define __GFP_THISNODE	((__force gfp_t)0x40000u)/* No fallback, no policies */
 #define __GFP_RECLAIMABLE ((__force gfp_t)0x80000u) /* Page is reclaimable */
 #define __GFP_MOVABLE	((__force gfp_t)0x100000u)  /* Page is movable */
+
+#ifdef CONFIG_KMEMCHECK
 #define __GFP_NOTRACK	((__force gfp_t)0x200000u)  /* Don't track with kmemcheck */
+#else
+#define __GFP_NOTRACK	((__force gfp_t)0)
+#endif
 
 /*
  * This may seem redundant, but it's a way of annotating false positives vs.

include/linux/kmemcheck.h

@@ -8,13 +8,15 @@
 extern int kmemcheck_enabled;
 
 /* The slab-related functions. */
-void kmemcheck_alloc_shadow(struct kmem_cache *s, gfp_t flags, int node,
-			    struct page *page, int order);
-void kmemcheck_free_shadow(struct kmem_cache *s, struct page *page, int order);
+void kmemcheck_alloc_shadow(struct page *page, int order, gfp_t flags, int node);
+void kmemcheck_free_shadow(struct page *page, int order);
 void kmemcheck_slab_alloc(struct kmem_cache *s, gfp_t gfpflags, void *object,
 			  size_t size);
 void kmemcheck_slab_free(struct kmem_cache *s, void *object, size_t size);
 
+void kmemcheck_pagealloc_alloc(struct page *p, unsigned int order,
+			       gfp_t gfpflags);
+
 void kmemcheck_show_pages(struct page *p, unsigned int n);
 void kmemcheck_hide_pages(struct page *p, unsigned int n);
 
@@ -27,6 +29,7 @@ void kmemcheck_mark_freed(void *address, unsigned int n);
 
 void kmemcheck_mark_unallocated_pages(struct page *p, unsigned int n);
 void kmemcheck_mark_uninitialized_pages(struct page *p, unsigned int n);
+void kmemcheck_mark_initialized_pages(struct page *p, unsigned int n);
 
 int kmemcheck_show_addr(unsigned long address);
 int kmemcheck_hide_addr(unsigned long address);
@@ -34,13 +37,12 @@ int kmemcheck_hide_addr(unsigned long address);
 #define kmemcheck_enabled 0
 
 static inline void
-kmemcheck_alloc_shadow(struct kmem_cache *s, gfp_t flags, int node,
-		       struct page *page, int order)
+kmemcheck_alloc_shadow(struct page *page, int order, gfp_t flags, int node)
 {
 }
 
 static inline void
-kmemcheck_free_shadow(struct kmem_cache *s, struct page *page, int order)
+kmemcheck_free_shadow(struct page *page, int order)
 {
 }
 
@@ -55,6 +57,11 @@ static inline void kmemcheck_slab_free(struct kmem_cache *s, void *object,
 {
 }
 
+static inline void kmemcheck_pagealloc_alloc(struct page *p,
+	unsigned int order, gfp_t gfpflags)
+{
+}
+
 static inline bool kmemcheck_page_is_tracked(struct page *p)
 {
 	return false;
@@ -75,6 +82,22 @@ static inline void kmemcheck_mark_initialized(void *address, unsigned int n)
 static inline void kmemcheck_mark_freed(void *address, unsigned int n)
 {
 }
+
+static inline void kmemcheck_mark_unallocated_pages(struct page *p,
+						    unsigned int n)
+{
+}
+
+static inline void kmemcheck_mark_uninitialized_pages(struct page *p,
+						      unsigned int n)
+{
+}
+
+static inline void kmemcheck_mark_initialized_pages(struct page *p,
+						    unsigned int n)
+{
+}
+
 #endif /* CONFIG_KMEMCHECK */
 
 #endif /* LINUX_KMEMCHECK_H */

mm/kmemcheck.c

+#include <linux/gfp.h>
 #include <linux/mm_types.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/kmemcheck.h>
 
-void kmemcheck_alloc_shadow(struct kmem_cache *s, gfp_t flags, int node,
-			   struct page *page, int order)
+void kmemcheck_alloc_shadow(struct page *page, int order, gfp_t flags, int node)
 {
 	struct page *shadow;
 	int pages;
@@ -16,7 +16,7 @@ void kmemcheck_alloc_shadow(struct kmem_cache *s, gfp_t flags, int node,
 	 * With kmemcheck enabled, we need to allocate a memory area for the
 	 * shadow bits as well.
 	 */
-	shadow = alloc_pages_node(node, flags, order);
+	shadow = alloc_pages_node(node, flags | __GFP_NOTRACK, order);
 	if (!shadow) {
 		if (printk_ratelimit())
 			printk(KERN_ERR "kmemcheck: failed to allocate "
@@ -33,23 +33,17 @@ void kmemcheck_alloc_shadow(struct kmem_cache *s, gfp_t flags, int node,
 	 * the memory accesses.
 	 */
 	kmemcheck_hide_pages(page, pages);
-
-	/*
-	 * Objects from caches that have a constructor don't get
-	 * cleared when they're allocated, so we need to do it here.
-	 */
-	if (s->ctor)
-		kmemcheck_mark_uninitialized_pages(page, pages);
-	else
-		kmemcheck_mark_unallocated_pages(page, pages);
 }
 
-void kmemcheck_free_shadow(struct kmem_cache *s, struct page *page, int order)
+void kmemcheck_free_shadow(struct page *page, int order)
 {
 	struct page *shadow;
 	int pages;
 	int i;
 
+	if (!kmemcheck_page_is_tracked(page))
+		return;
+
 	pages = 1 << order;
 
 	kmemcheck_show_pages(page, pages);
@@ -101,3 +95,28 @@ void kmemcheck_slab_free(struct kmem_cache *s, void *object, size_t size)
 	if (!s->ctor && !(s->flags & SLAB_DESTROY_BY_RCU))
 		kmemcheck_mark_freed(object, size);
 }
+
+void kmemcheck_pagealloc_alloc(struct page *page, unsigned int order,
+			       gfp_t gfpflags)
+{
+	int pages;
+
+	if (gfpflags & (__GFP_HIGHMEM | __GFP_NOTRACK))
+		return;
+
+	pages = 1 << order;
+
+	/*
+	 * NOTE: We choose to track GFP_ZERO pages too; in fact, they
+	 * can become uninitialized by copying uninitialized memory
+	 * into them.
+	 */
+
+	/* XXX: Can use zone->node for node? */
+	kmemcheck_alloc_shadow(page, order, gfpflags, -1);
+
+	if (gfpflags & __GFP_ZERO)
+		kmemcheck_mark_initialized_pages(page, pages);
+	else
+		kmemcheck_mark_uninitialized_pages(page, pages);
+}

mm/page_alloc.c

@@ -23,6 +23,7 @@
 #include <linux/bootmem.h>
 #include <linux/compiler.h>
 #include <linux/kernel.h>
+#include <linux/kmemcheck.h>
 #include <linux/module.h>
 #include <linux/suspend.h>
 #include <linux/pagevec.h>
@@ -546,6 +547,8 @@ static void __free_pages_ok(struct page *page, unsigned int order)
 	int i;
 	int bad = 0;
 
+	kmemcheck_free_shadow(page, order);
+
 	for (i = 0 ; i < (1 << order) ; ++i)
 		bad += free_pages_check(page + i);
 	if (bad)
@@ -994,6 +997,8 @@ static void free_hot_cold_page(struct page *page, int cold)
 	struct per_cpu_pages *pcp;
 	unsigned long flags;
 
+	kmemcheck_free_shadow(page, 0);
+
 	if (PageAnon(page))
 		page->mapping = NULL;
 	if (free_pages_check(page))
@@ -1047,6 +1052,16 @@ void split_page(struct page *page, unsigned int order)
 
 	VM_BUG_ON(PageCompound(page));
 	VM_BUG_ON(!page_count(page));
+
+#ifdef CONFIG_KMEMCHECK
+	/*
+	 * Split shadow pages too, because free(page[0]) would
+	 * otherwise free the whole shadow.
+	 */
+	if (kmemcheck_page_is_tracked(page))
+		split_page(virt_to_page(page[0].shadow), order);
+#endif
+
 	for (i = 1; i < (1 << order); i++)
 		set_page_refcounted(page + i);
 }
@@ -1667,7 +1682,10 @@ __alloc_pages_internal(gfp_t gfp_mask, unsigned int order,
 		dump_stack();
 		show_mem();
 	}
+	return page;
 got_pg:
+	if (kmemcheck_enabled)
+		kmemcheck_pagealloc_alloc(page, order, gfp_mask);
 	return page;
 }
 EXPORT_SYMBOL(__alloc_pages_internal);

mm/slab.c

@@ -1612,7 +1612,7 @@ static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid)
 	if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
 		flags |= __GFP_RECLAIMABLE;
 
-	page = alloc_pages_node(nodeid, flags, cachep->gfporder);
+	page = alloc_pages_node(nodeid, flags | __GFP_NOTRACK, cachep->gfporder);
 	if (!page)
 		return NULL;
 
@@ -1626,8 +1626,14 @@ static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid)
 	for (i = 0; i < nr_pages; i++)
 		__SetPageSlab(page + i);
 
-	if (kmemcheck_enabled && !(cachep->flags & SLAB_NOTRACK))
-		kmemcheck_alloc_shadow(cachep, flags, nodeid, page, cachep->gfporder);
+	if (kmemcheck_enabled && !(cachep->flags & SLAB_NOTRACK)) {
+		kmemcheck_alloc_shadow(page, cachep->gfporder, flags, nodeid);
+
+		if (cachep->ctor)
+			kmemcheck_mark_uninitialized_pages(page, nr_pages);
+		else
+			kmemcheck_mark_unallocated_pages(page, nr_pages);
+	}
 
 	return page_address(page);
 }
@@ -1641,8 +1647,7 @@ static void kmem_freepages(struct kmem_cache *cachep, void *addr)
 	struct page *page = virt_to_page(addr);
 	const unsigned long nr_freed = i;
 
-	if (kmemcheck_page_is_tracked(page))
-		kmemcheck_free_shadow(cachep, page, cachep->gfporder);
+	kmemcheck_free_shadow(page, cachep->gfporder);
 
 	if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
 		sub_zone_page_state(page_zone(page),

mm/slub.c

@@ -1066,6 +1066,8 @@ static inline struct page *alloc_slab_page(gfp_t flags, int node,
 {
 	int order = oo_order(oo);
 
+	flags |= __GFP_NOTRACK;
+
 	if (node == -1)
 		return alloc_pages(flags, order);
 	else
@@ -1097,7 +1099,18 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 	if (kmemcheck_enabled
 		&& !(s->flags & (SLAB_NOTRACK | DEBUG_DEFAULT_FLAGS)))
 	{
-		kmemcheck_alloc_shadow(s, flags, node, page, compound_order(page));
+		int pages = 1 << oo_order(oo);
+
+		kmemcheck_alloc_shadow(page, oo_order(oo), flags, node);
+
+		/*
+		 * Objects from caches that have a constructor don't get
+		 * cleared when they're allocated, so we need to do it here.
+		 */
+		if (s->ctor)
+			kmemcheck_mark_uninitialized_pages(page, pages);
+		else
+			kmemcheck_mark_unallocated_pages(page, pages);
 	}
 
 	page->objects = oo_objects(oo);
@@ -1173,8 +1186,7 @@ static void __free_slab(struct kmem_cache *s, struct page *page)
 		__ClearPageSlubDebug(page);
 	}
 
-	if (kmemcheck_page_is_tracked(page))
-		kmemcheck_free_shadow(s, page, compound_order(page));
+	kmemcheck_free_shadow(page, compound_order(page));
 
 	mod_zone_page_state(page_zone(page),
 		(s->flags & SLAB_RECLAIM_ACCOUNT) ?
@@ -2734,9 +2746,10 @@ EXPORT_SYMBOL(__kmalloc);
 
 static void *kmalloc_large_node(size_t size, gfp_t flags, int node)
 {
-	struct page *page = alloc_pages_node(node, flags | __GFP_COMP,
-						get_order(size));
+	struct page *page;
 
+	flags |= __GFP_COMP | __GFP_NOTRACK;
+	page = alloc_pages_node(node, flags, get_order(size));
 	if (page)
 		return page_address(page);
 	else