[PATCH 1/3] kmemcheck: prepare for SLAB hooks

[PATCH 1/3] kmemcheck: prepare for SLAB hooks

[Pekka J Enberg]

From: Pekka Enberg <penberg@cs.helsinki.fi>

Make mm/slub_kmemcheck.c more generic in preparation for adding kmemcheck hooks
to SLAB which does not use compound pages by default and has slightly different
way for keeping track of object size than SLUB.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
---
 include/linux/slub_kmemcheck.h |   19 +++++++++++--------
 mm/slub.c                      |    8 ++++----
 mm/slub_kmemcheck.c            |   23 ++++++++++-------------
 3 files changed, 25 insertions(+), 25 deletions(-)

Index: kmemcheck/include/linux/slub_kmemcheck.h
===================================================================
--- kmemcheck.orig/include/linux/slub_kmemcheck.h	2008-05-08 23:50:38.000000000 +0300
+++ kmemcheck/include/linux/slub_kmemcheck.h	2008-05-08 23:50:45.000000000 +0300
@@ -3,28 +3,31 @@
 
 #ifdef CONFIG_KMEMCHECK
 void kmemcheck_alloc_shadow(struct kmem_cache *s, gfp_t flags, int node,
-			   struct page *page);
-void kmemcheck_free_shadow(struct kmem_cache *s, struct page *page);
-void kmemcheck_slab_alloc(struct kmem_cache *s, gfp_t gfpflags, void *object);
-void kmemcheck_slab_free(struct kmem_cache *s, void *object);
+			   struct page *page, int order);
+void kmemcheck_free_shadow(struct kmem_cache *s, 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);
 #else
 static inline void
 kmemcheck_alloc_shadow(struct kmem_cache *s, gfp_t flags, int node,
-		       struct page *page)
+		       struct page *page, int order)
 {
 }
 
 static inline void
-kmemcheck_free_shadow(struct kmem_cache *s, struct page *page)
+kmemcheck_free_shadow(struct kmem_cache *s, struct page *page, int order)
 {
 }
 
 static inline void
-kmemcheck_slab_alloc(struct kmem_cache *s, gfp_t gfpflags, void *object)
+kmemcheck_slab_alloc(struct kmem_cache *s, gfp_t gfpflags, void *object,
+		     size_t size)
 {
 }
 
-static inline void kmemcheck_slab_free(struct kmem_cache *s, void *object)
+static inline void kmemcheck_slab_free(struct kmem_cache *s, void *object,
+				       size_t size)
 {
 }
 #endif /* CONFIG_KMEMCHECK */
Index: kmemcheck/mm/slub.c
===================================================================
--- kmemcheck.orig/mm/slub.c	2008-05-08 23:49:15.000000000 +0300
+++ kmemcheck/mm/slub.c	2008-05-08 23:50:45.000000000 +0300
@@ -1126,7 +1126,7 @@
 	}
 
 	if (kmemcheck_enabled && !(s->flags & SLAB_NOTRACK))
-		kmemcheck_alloc_shadow(s, flags, node, page);
+		kmemcheck_alloc_shadow(s, flags, node, page, compound_order(page));
 
 	page->objects = oo_objects(oo);
 	mod_zone_page_state(page_zone(page),
@@ -1202,7 +1202,7 @@
 	}
 
 	if (kmemcheck_page_is_tracked(page) && !(s->flags & SLAB_NOTRACK))
-		kmemcheck_free_shadow(s, page);
+		kmemcheck_free_shadow(s, page, compound_order(page));
 
 	mod_zone_page_state(page_zone(page),
 		(s->flags & SLAB_RECLAIM_ACCOUNT) ?
@@ -1654,7 +1654,7 @@
 	if (unlikely((gfpflags & __GFP_ZERO) && object))
 		memset(object, 0, c->objsize);
 
-	kmemcheck_slab_alloc(s, gfpflags, object);
+	kmemcheck_slab_alloc(s, gfpflags, object, c->objsize);
 	return object;
 }
 
@@ -1757,7 +1757,7 @@
 	struct kmem_cache_cpu *c;
 	unsigned long flags;
 
-	kmemcheck_slab_free(s, object);
+	kmemcheck_slab_free(s, object, c->objsize);
 
 	local_irq_save(flags);
 	c = get_cpu_slab(s, smp_processor_id());
Index: kmemcheck/mm/slub_kmemcheck.c
===================================================================
--- kmemcheck.orig/mm/slub_kmemcheck.c	2008-05-08 23:50:38.000000000 +0300
+++ kmemcheck/mm/slub_kmemcheck.c	2008-05-08 23:50:45.000000000 +0300
@@ -5,12 +5,11 @@
 #include <linux/slub_kmemcheck.h>
 
 void kmemcheck_alloc_shadow(struct kmem_cache *s, gfp_t flags, int node,
-			   struct page *page)
+			   struct page *page, int order)
 {
 	struct page *shadow;
-	int order, pages;
+	int pages;
 
-	order = compound_order(page);
 	pages = 1 << order;
 
 	/*
@@ -52,12 +51,11 @@
 		pages);
 }
 
-void kmemcheck_free_shadow(struct kmem_cache *s, struct page *page)
+void kmemcheck_free_shadow(struct kmem_cache *s, struct page *page, int order)
 {
 	struct page *shadow = virt_to_page(page->shadow);
-	int order, pages;
+	int pages;
 
-	order = compound_order(page);
 	pages = 1 << order;
 
 	kmemcheck_show_pages(page, pages);
@@ -71,8 +69,8 @@
 	__free_pages(shadow, order);
 }
 
-void
-kmemcheck_slab_alloc(struct kmem_cache *s, gfp_t gfpflags, void *object)
+void kmemcheck_slab_alloc(struct kmem_cache *s, gfp_t gfpflags, void *object,
+			  size_t size)
 {
 	if (gfpflags & __GFP_ZERO)
 		return;
@@ -88,22 +86,21 @@
 		 * faults are not acceptable, the slab cache itself
 		 * should be marked NOTRACK.
 		 */
-		kmemcheck_mark_initialized(object, s->objsize);
+		kmemcheck_mark_initialized(object, size);
 	} else if (!s->ctor) {
 		/*
 		 * New objects should be marked uninitialized before
 		 * they're returned to the called.
 		 */
-		kmemcheck_mark_uninitialized(object, s->objsize);
+		kmemcheck_mark_uninitialized(object, size);
 	}
 }
 
-void
-kmemcheck_slab_free(struct kmem_cache *s, void *object)
+void kmemcheck_slab_free(struct kmem_cache *s, void *object, size_t size)
 {
 	/* TODO: RCU freeing is unsupported for now; hide false positives. */
 	if (!s->ctor && !(s->flags & SLAB_DESTROY_BY_RCU))
-		kmemcheck_mark_freed(object, s->objsize);
+		kmemcheck_mark_freed(object, size);
 }
 
 #ifdef CONFIG_KMEMCHECK_SELFTEST

Re: [PATCH 1/3] kmemcheck: prepare for SLAB hooks

[Pekka Enberg]

On Fri, May 9, 2008 at 12:02 AM, Pekka J Enberg <penberg@cs.helsinki.fi> wrote:
> From: Pekka Enberg <penberg@cs.helsinki.fi>
>
> Make mm/slub_kmemcheck.c more generic in preparation for adding kmemcheck hooks
> to SLAB which does not use compound pages by default and has slightly different
> way for keeping track of object size than SLUB.

And oh, the file ought to be renamed now; it's not SLUB specific at all anymore.

Re: [PATCH 1/3] kmemcheck: prepare for SLAB hooks

[Vegard Nossum]

On Thu, May 8, 2008 at 11:02 PM, Pekka J Enberg <penberg@cs.helsinki.fi> wrote:
> From: Pekka Enberg <penberg@cs.helsinki.fi>
>
> Make mm/slub_kmemcheck.c more generic in preparation for adding kmemcheck hooks
> to SLAB which does not use compound pages by default and has slightly different
> way for keeping track of object size than SLUB.
>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Christoph Lameter <clameter@sgi.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Vegard Nossum <vegard.nossum@gmail.com>
> Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
> ---
>  include/linux/slub_kmemcheck.h |   19 +++++++++++--------
>  mm/slub.c                      |    8 ++++----
>  mm/slub_kmemcheck.c            |   23 ++++++++++-------------
>  3 files changed, 25 insertions(+), 25 deletions(-)

[sniip]

> @@ -1757,7 +1757,7 @@
>        struct kmem_cache_cpu *c;
>        unsigned long flags;
>
> -       kmemcheck_slab_free(s, object);
> +       kmemcheck_slab_free(s, object, c->objsize);

Hm, "'c' is used uninitialized in this function". I guess it should be
moved a bit downwards. Can you fix it?

Vegard

-- 
"The animistic metaphor of the bug that maliciously sneaked in while
the programmer was not looking is intellectually dishonest as it
disguises that the error is the programmer's own creation."
	-- E. W. Dijkstra, EWD1036