[PATCH] kmemcheck: add hooks for the page allocator

Vegard Nossum
2009-02-21T13:37:43Z

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>
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
---
arch/x86/include/asm/thread_info.h | 4 +-
arch/x86/mm/kmemcheck/shadow.c | 8 ++++++
include/linux/gfp.h | 5 ++++
include/linux/kmemcheck.h | 33 ++++++++++++++++++++++----
mm/kmemcheck.c | 45 +++++++++++++++++++++++++----------
mm/page_alloc.c | 8 ++++++
mm/slab.c | 15 ++++++++----
mm/slub.c | 23 ++++++++++++++----
8 files changed, 111 insertions(+), 30 deletions(-)

diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index df9d5f7..b5392e3 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -149,9 +149,9 @@ 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
diff --git a/arch/x86/mm/kmemcheck/shadow.c b/arch/x86/mm/kmemcheck/shadow.c
index 196dddc..aab8c18 100644
--- a/arch/x86/mm/kmemcheck/shadow.c
+++ b/arch/x86/mm/kmemcheck/shadow.c
@@ -86,6 +86,14 @@ 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;
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index e56f72f..e2ec7d5 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -50,7 +50,12 @@ 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

#define __GFP_BITS_SHIFT 22 /* Room for 22 __GFP_FOO bits */
#define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
diff --git a/include/linux/kmemcheck.h b/include/linux/kmemcheck.h
index 7073121..2ee402e 100644
--- a/include/linux/kmemcheck.h
+++ b/include/linux/kmemcheck.h
@@ -42,13 +42,15 @@ extern int kmemcheck_enabled;
void kmemcheck_init(void);

/* 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);

@@ -61,6 +63,7 @@ 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);
@@ -77,13 +80,13 @@ static inline void kmemcheck_init(void)
}

static inline void
-kmemcheck_alloc_shadow(struct kmem_cache *s, gfp_t flags, int node,
+kmemcheck_alloc_shadow(int ctor, gfp_t flags, int node,
struct page *page, int order)
{
}

static inline void
-kmemcheck_free_shadow(struct kmem_cache *s, struct page *page, int order)
+kmemcheck_free_shadow(struct page *page, int order)
{
}

@@ -98,6 +101,11 @@ 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;
@@ -119,6 +127,21 @@ 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)
+{
+}
+
#define kmemcheck_annotate_bitfield(field) do { } while (0)
#endif /* CONFIG_KMEMCHECK */

diff --git a/mm/kmemcheck.c b/mm/kmemcheck.c
index eaa41b8..fd814fd 100644
--- a/mm/kmemcheck.c
+++ b/mm/kmemcheck.c
@@ -1,10 +1,10 @@
+#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);
+}
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5675b30..cf247fd 100644
--- a/mm/page_alloc.c
+++ b/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>
@@ -549,6 +550,8 @@ 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)
@@ -1000,6 +1003,8 @@ 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))
@@ -1667,7 +1672,10 @@ nopage:
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);
diff --git a/mm/slab.c b/mm/slab.c
index d6735bd..4fa7b7b 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1600,7 +1600,7 @@ 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;

@@ -1614,8 +1614,14 @@ 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);
}
@@ -1629,8 +1635,7 @@ 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),
diff --git a/mm/slub.c b/mm/slub.c
index 628e3ec..b9c8169 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1069,6 +1069,8 @@ 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
@@ -1100,7 +1102,18 @@ 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);
@@ -1176,8 +1189,7 @@ 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) ?
@@ -2686,9 +2698,10 @@ 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
--
1.6.0.6