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slub: convert SLAB_DEBUG_FREE to SLAB_CONSISTENCY_CHECKS

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SLAB_DEBUG_FREE allows expensive consistency checks at free to be turned
on or off.  Expand its use to be able to turn off all consistency
checks.  This gives a nice speed up if you only want features such as
poisoning or tracing.

Credit to Mathias Krause for the original work which inspired this
series

Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Laura Abbott 2016-03-15 14:55:06 -07:00 committed by Linus Torvalds
parent 804aa132d3
commit becfda68ab
5 changed files with 69 additions and 44 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

4
Documentation/vm/slub.txt
View file

@ -35,8 +35,8 @@ slub_debug=<Debug-Options>,<slab name>
Enable options only for select slabs
Possible debug options are
F Sanity checks on (enables SLAB_DEBUG_FREE. Sorry
SLAB legacy issues)
F Sanity checks on (enables SLAB_DEBUG_CONSISTENCY_CHECKS
Sorry SLAB legacy issues)
Z Red zoning
P Poisoning (object and padding)
U User tracking (free and alloc)

2
include/linux/slab.h
View file

@ -20,7 +20,7 @@
* Flags to pass to kmem_cache_create().
* The ones marked DEBUG are only valid if CONFIG_DEBUG_SLAB is set.
*/
#define SLAB_DEBUG_FREE 0x00000100UL /* DEBUG: Perform (expensive) checks on free */
#define SLAB_CONSISTENCY_CHECKS 0x00000100UL /* DEBUG: Perform (expensive) checks on alloc/free */
#define SLAB_RED_ZONE 0x00000400UL /* DEBUG: Red zone objs in a cache */
#define SLAB_POISON 0x00000800UL /* DEBUG: Poison objects */
#define SLAB_HWCACHE_ALIGN 0x00002000UL /* Align objs on cache lines */

5
mm/slab.h
View file

@ -125,7 +125,7 @@ static inline unsigned long kmem_cache_flags(unsigned long object_size,
#define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)
#elif defined(CONFIG_SLUB_DEBUG)
#define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
SLAB_TRACE | SLAB_DEBUG_FREE)
SLAB_TRACE | SLAB_CONSISTENCY_CHECKS)
#else
#define SLAB_DEBUG_FLAGS (0)
#endif
@ -311,7 +311,8 @@ static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)
* to not do even the assignment. In that case, slab_equal_or_root
* will also be a constant.
*/
if (!memcg_kmem_enabled() && !unlikely(s->flags & SLAB_DEBUG_FREE))
if (!memcg_kmem_enabled() &&
!unlikely(s->flags & SLAB_CONSISTENCY_CHECKS))
return s;
page = virt_to_head_page(x);

100
mm/slub.c
View file

@ -160,7 +160,7 @@ static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s)
*/
#define MAX_PARTIAL 10
#define DEBUG_DEFAULT_FLAGS (SLAB_DEBUG_FREE | SLAB_RED_ZONE | \
#define DEBUG_DEFAULT_FLAGS (SLAB_CONSISTENCY_CHECKS | SLAB_RED_ZONE | \
SLAB_POISON | SLAB_STORE_USER)
/*
@ -1007,20 +1007,32 @@ static void setup_object_debug(struct kmem_cache *s, struct page *page,
init_tracking(s, object);
}
static noinline int alloc_debug_processing(struct kmem_cache *s,
static inline int alloc_consistency_checks(struct kmem_cache *s,
struct page *page,
void *object, unsigned long addr)
{
if (!check_slab(s, page))
goto bad;
return 0;
if (!check_valid_pointer(s, page, object)) {
object_err(s, page, object, "Freelist Pointer check fails");
goto bad;
return 0;
}
if (!check_object(s, page, object, SLUB_RED_INACTIVE))
goto bad;
return 0;
return 1;
}
static noinline int alloc_debug_processing(struct kmem_cache *s,
struct page *page,
void *object, unsigned long addr)
{
if (s->flags & SLAB_CONSISTENCY_CHECKS) {
if (!alloc_consistency_checks(s, page, object, addr))
goto bad;
}
/* Success perform special debug activities for allocs */
if (s->flags & SLAB_STORE_USER)
@ -1043,6 +1055,38 @@ static noinline int alloc_debug_processing(struct kmem_cache *s,
return 0;
}
static inline int free_consistency_checks(struct kmem_cache *s,
struct page *page, void *object, unsigned long addr)
{
if (!check_valid_pointer(s, page, object)) {
slab_err(s, page, "Invalid object pointer 0x%p", object);
return 0;
}
if (on_freelist(s, page, object)) {
object_err(s, page, object, "Object already free");
return 0;
}
if (!check_object(s, page, object, SLUB_RED_ACTIVE))
return 0;
if (unlikely(s != page->slab_cache)) {
if (!PageSlab(page)) {
slab_err(s, page, "Attempt to free object(0x%p) "
"outside of slab", object);
} else if (!page->slab_cache) {
pr_err("SLUB <none>: no slab for object 0x%p.\n",
object);
dump_stack();
} else
object_err(s, page, object,
"page slab pointer corrupt.");
return 0;
}
return 1;
}
/* Supports checking bulk free of a constructed freelist */
static noinline int free_debug_processing(
struct kmem_cache *s, struct page *page,
@ -1058,37 +1102,17 @@ static noinline int free_debug_processing(
spin_lock_irqsave(&n->list_lock, flags);
slab_lock(page);
if (!check_slab(s, page))
goto out;
if (s->flags & SLAB_CONSISTENCY_CHECKS) {
if (!check_slab(s, page))
goto out;
}
next_object:
cnt++;
if (!check_valid_pointer(s, page, object)) {
slab_err(s, page, "Invalid object pointer 0x%p", object);
goto out;
}
if (on_freelist(s, page, object)) {
object_err(s, page, object, "Object already free");
goto out;
}
if (!check_object(s, page, object, SLUB_RED_ACTIVE))
goto out;
if (unlikely(s != page->slab_cache)) {
if (!PageSlab(page)) {
slab_err(s, page, "Attempt to free object(0x%p) "
"outside of slab", object);
} else if (!page->slab_cache) {
pr_err("SLUB <none>: no slab for object 0x%p.\n",
object);
dump_stack();
} else
object_err(s, page, object,
"page slab pointer corrupt.");
goto out;
if (s->flags & SLAB_CONSISTENCY_CHECKS) {
if (!free_consistency_checks(s, page, object, addr))
goto out;
}
if (s->flags & SLAB_STORE_USER)
@ -1145,7 +1169,7 @@ static int __init setup_slub_debug(char *str)
for (; *str && *str != ','; str++) {
switch (tolower(*str)) {
case 'f':
slub_debug |= SLAB_DEBUG_FREE;
slub_debug |= SLAB_CONSISTENCY_CHECKS;
break;
case 'z':
slub_debug |= SLAB_RED_ZONE;
@ -1449,7 +1473,7 @@ static void __free_slab(struct kmem_cache *s, struct page *page)
int order = compound_order(page);
int pages = 1 << order;
if (kmem_cache_debug(s)) {
if (s->flags & SLAB_CONSISTENCY_CHECKS) {
void *p;
slab_pad_check(s, page);
@ -4769,16 +4793,16 @@ SLAB_ATTR_RO(total_objects);
static ssize_t sanity_checks_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_DEBUG_FREE));
return sprintf(buf, "%d\n", !!(s->flags & SLAB_CONSISTENCY_CHECKS));
}
static ssize_t sanity_checks_store(struct kmem_cache *s,
const char *buf, size_t length)
{
s->flags &= ~SLAB_DEBUG_FREE;
s->flags &= ~SLAB_CONSISTENCY_CHECKS;
if (buf[0] == '1') {
s->flags &= ~__CMPXCHG_DOUBLE;
s->flags |= SLAB_DEBUG_FREE;
s->flags |= SLAB_CONSISTENCY_CHECKS;
}
return length;
}
@ -5313,7 +5337,7 @@ static char *create_unique_id(struct kmem_cache *s)
*p++ = 'd';
if (s->flags & SLAB_RECLAIM_ACCOUNT)
*p++ = 'a';
if (s->flags & SLAB_DEBUG_FREE)
if (s->flags & SLAB_CONSISTENCY_CHECKS)
*p++ = 'F';
if (!(s->flags & SLAB_NOTRACK))
*p++ = 't';

2
tools/vm/slabinfo.c
View file

@ -135,7 +135,7 @@ static void usage(void)
"\nValid debug options (FZPUT may be combined)\n"
"a / A Switch on all debug options (=FZUP)\n"
"- Switch off all debug options\n"
"f / F Sanity Checks (SLAB_DEBUG_FREE)\n"
"f / F Sanity Checks (SLAB_CONSISTENCY_CHECKS)\n"
"z / Z Redzoning\n"
"p / P Poisoning\n"
"u / U Tracking\n"