2011-06-02 07:18:30

by Suleiman Souhlal

Subject: [PATCH] SLAB: Record actual last user of freed objects.

Currently, when using CONFIG_DEBUG_SLAB, we put in kfree() or
kmem_cache_free() as the last user of free objects, which is not
very useful, so change it to the caller of those functions instead.

Signed-off-by: Suleiman Souhlal <[email protected]>
---
mm/slab.c | 9 +++++----
1 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index 98f114d..615e76c 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3603,13 +3603,14 @@ free_done:
* Release an obj back to its cache. If the obj has a constructed state, it must
* be in this state _before_ it is released. Called with disabled ints.
*/
-static inline void __cache_free(struct kmem_cache *cachep, void *objp)
+static inline void __cache_free(struct kmem_cache *cachep, void *objp,
+ void *caller)
{
struct array_cache *ac = cpu_cache_get(cachep);

check_irq_off();
kmemleak_free_recursive(objp, cachep->flags);
- objp = cache_free_debugcheck(cachep, objp, __builtin_return_address(0));
+ objp = cache_free_debugcheck(cachep, objp, caller);

kmemcheck_slab_free(cachep, objp, obj_size(cachep));

@@ -3800,7 +3801,7 @@ void kmem_cache_free(struct kmem_cache *cachep, void *objp)
debug_check_no_locks_freed(objp, obj_size(cachep));
if (!(cachep->flags & SLAB_DEBUG_OBJECTS))
debug_check_no_obj_freed(objp, obj_size(cachep));
- __cache_free(cachep, objp);
+ __cache_free(cachep, objp, __builtin_return_address(0));
local_irq_restore(flags);

trace_kmem_cache_free(_RET_IP_, objp);
@@ -3830,7 +3831,7 @@ void kfree(const void *objp)
c = virt_to_cache(objp);
debug_check_no_locks_freed(objp, obj_size(c));
debug_check_no_obj_freed(objp, obj_size(c));
- __cache_free(c, (void *)objp);
+ __cache_free(c, (void *)objp, __builtin_return_address(0));
local_irq_restore(flags);
}
EXPORT_SYMBOL(kfree);
--
1.7.3.1

2011-06-02 17:12:11

by David Rientjes

Subject: Re: [PATCH] SLAB: Record actual last user of freed objects.

On Thu, 2 Jun 2011, Suleiman Souhlal wrote:

> Currently, when using CONFIG_DEBUG_SLAB, we put in kfree() or
> kmem_cache_free() as the last user of free objects, which is not
> very useful, so change it to the caller of those functions instead.
>
> Signed-off-by: Suleiman Souhlal <[email protected]>

Acked-by: David Rientjes <[email protected]>

2011-06-03 14:05:12

by Christoph Lameter (Ampere)

Subject: Re: [PATCH] SLAB: Record actual last user of freed objects.

On Thu, 2 Jun 2011, David Rientjes wrote:

> On Thu, 2 Jun 2011, Suleiman Souhlal wrote:
>
> > Currently, when using CONFIG_DEBUG_SLAB, we put in kfree() or
> > kmem_cache_free() as the last user of free objects, which is not
> > very useful, so change it to the caller of those functions instead.
> >
> > Signed-off-by: Suleiman Souhlal <[email protected]>
>
> Acked-by: David Rientjes <[email protected]>

Well note that this increases the overhead of a hot code path. But slub
does the same

Acked-by: Christoph Lameter <[email protected]>

2011-06-03 18:07:22

by Pekka Enberg

Subject: Re: [PATCH] SLAB: Record actual last user of freed objects.

On Fri, Jun 3, 2011 at 5:05 PM, Christoph Lameter <[email protected]> wrote:
> On Thu, 2 Jun 2011, David Rientjes wrote:
>
>> On Thu, 2 Jun 2011, Suleiman Souhlal wrote:
>>
>> > Currently, when using CONFIG_DEBUG_SLAB, we put in kfree() or
>> > kmem_cache_free() as the last user of free objects, which is not
>> > very useful, so change it to the caller of those functions instead.
>> >
>> > Signed-off-by: Suleiman Souhlal <[email protected]>
>>
>> Acked-by: David Rientjes <[email protected]>
>
> Well note that this increases the overhead of a hot code path. But slub
> does the same
>
> Acked-by: Christoph Lameter <[email protected]>

Applied, thanks!