On Tue, 28 Sep 2010, David Rientjes wrote:
> I'm wondering if we should make that option configurable regardless of
> CONFIG_EMBEDDED, it's a large savings if you're never going to be doing
> any debugging on Pekka's for-next:
>
> text data bss dec hex filename
> 25817 1473 288 27578 6bba slub.o.debug
> 10742 232 256 11230 2bde slub.o.nodebug
We know. On the other hand it is essential to have that capability in
enterprise kernels so that you can just reboot with full debugging and
then get a detailed report on what went wrong. Slab diagnostics and
resiliency are critical for other kernel components.
Updated patch:
Subject: SLUB: Pass active and inactive redzone flags instead of boolean to debug functions
Pass the actual values used for inactive and active redzoning to the
functions that check the objects. Avoids a lot of the ? : things to
lookup the values in the functions.
Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
---
mm/slub.c | 33 ++++++++++++++-------------------
1 file changed, 14 insertions(+), 19 deletions(-)
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c 2010-09-29 07:11:38.000000000 -0500
+++ linux-2.6/mm/slub.c 2010-09-29 07:12:26.000000000 -0500
@@ -490,7 +490,7 @@ static void slab_err(struct kmem_cache *
dump_stack();
}
-static void init_object(struct kmem_cache *s, void *object, int active)
+static void init_object(struct kmem_cache *s, void *object, u8 val)
{
u8 *p = object;
@@ -500,9 +500,7 @@ static void init_object(struct kmem_cach
}
if (s->flags & SLAB_RED_ZONE)
- memset(p + s->objsize,
- active ? SLUB_RED_ACTIVE : SLUB_RED_INACTIVE,
- s->inuse - s->objsize);
+ memset(p + s->objsize, val, s->inuse - s->objsize);
}
static u8 *check_bytes(u8 *start, unsigned int value, unsigned int bytes)
@@ -637,17 +635,14 @@ static int slab_pad_check(struct kmem_ca
}
static int check_object(struct kmem_cache *s, struct page *page,
- void *object, int active)
+ void *object, u8 val)
{
u8 *p = object;
u8 *endobject = object + s->objsize;
if (s->flags & SLAB_RED_ZONE) {
- unsigned int red =
- active ? SLUB_RED_ACTIVE : SLUB_RED_INACTIVE;
-
if (!check_bytes_and_report(s, page, object, "Redzone",
- endobject, red, s->inuse - s->objsize))
+ endobject, val, s->inuse - s->objsize))
return 0;
} else {
if ((s->flags & SLAB_POISON) && s->objsize < s->inuse) {
@@ -657,7 +652,7 @@ static int check_object(struct kmem_cach
}
if (s->flags & SLAB_POISON) {
- if (!active && (s->flags & __OBJECT_POISON) &&
+ if (val != SLUB_RED_ACTIVE && (s->flags & __OBJECT_POISON) &&
(!check_bytes_and_report(s, page, p, "Poison", p,
POISON_FREE, s->objsize - 1) ||
!check_bytes_and_report(s, page, p, "Poison",
@@ -669,7 +664,7 @@ static int check_object(struct kmem_cach
check_pad_bytes(s, page, p);
}
- if (!s->offset && active)
+ if (!s->offset && val == SLUB_RED_ACTIVE)
/*
* Object and freepointer overlap. Cannot check
* freepointer while object is allocated.
@@ -887,7 +882,7 @@ static void setup_object_debug(struct km
if (!(s->flags & (SLAB_STORE_USER|SLAB_RED_ZONE|__OBJECT_POISON)))
return;
- init_object(s, object, 0);
+ init_object(s, object, SLUB_RED_INACTIVE);
init_tracking(s, object);
}
@@ -907,14 +902,14 @@ static noinline int alloc_debug_processi
goto bad;
}
- if (!check_object(s, page, object, 0))
+ if (!check_object(s, page, object, SLUB_RED_INACTIVE))
goto bad;
/* Success perform special debug activities for allocs */
if (s->flags & SLAB_STORE_USER)
set_track(s, object, TRACK_ALLOC, addr);
trace(s, page, object, 1);
- init_object(s, object, 1);
+ init_object(s, object, SLUB_RED_ACTIVE);
return 1;
bad:
@@ -947,7 +942,7 @@ static noinline int free_debug_processin
goto fail;
}
- if (!check_object(s, page, object, 1))
+ if (!check_object(s, page, object, SLUB_RED_ACTIVE))
return 0;
if (unlikely(s != page->slab)) {
@@ -971,7 +966,7 @@ static noinline int free_debug_processin
if (s->flags & SLAB_STORE_USER)
set_track(s, object, TRACK_FREE, addr);
trace(s, page, object, 0);
- init_object(s, object, 0);
+ init_object(s, object, SLUB_RED_INACTIVE);
return 1;
fail:
@@ -1075,7 +1070,7 @@ static inline int free_debug_processing(
static inline int slab_pad_check(struct kmem_cache *s, struct page *page)
{ return 1; }
static inline int check_object(struct kmem_cache *s, struct page *page,
- void *object, int active) { return 1; }
+ void *object, u8 val) { return 1; }
static inline void add_full(struct kmem_cache_node *n, struct page *page) {}
static inline unsigned long kmem_cache_flags(unsigned long objsize,
unsigned long flags, const char *name,
@@ -1235,7 +1230,7 @@ static void __free_slab(struct kmem_cach
slab_pad_check(s, page);
for_each_object(p, s, page_address(page),
page->objects)
- check_object(s, page, p, 0);
+ check_object(s, page, p, SLUB_RED_INACTIVE);
}
kmemcheck_free_shadow(page, compound_order(page));
@@ -2143,7 +2138,7 @@ static void early_kmem_cache_node_alloc(
page->inuse++;
kmem_cache_node->node[node] = n;
#ifdef CONFIG_SLUB_DEBUG
- init_object(kmem_cache_node, n, 1);
+ init_object(kmem_cache_node, n, SLUB_RED_ACTIVE);
init_tracking(kmem_cache_node, n);
#endif
init_kmem_cache_node(n, kmem_cache_node);
--
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