Re: [PATCH 03/10] Add the memory allocation/freeing hooks for kmemleak

[Catalin Marinas]

Hi Pekka,

On 11/07/06, Pekka Enberg <penberg@xxxxxxxxxxxxxx> wrote:
> On 7/11/06, Catalin Marinas <catalin.marinas@xxxxxxxxx> wrote:
> > diff --git a/mm/slab.c b/mm/slab.c
> > index 85c2e03..2752272 100644
> > --- a/mm/slab.c
> > +++ b/mm/slab.c
> > @@ -2967,6 +2967,7 @@ #endif
> >                 STATS_INC_ALLOCMISS(cachep);
> >                 objp = cache_alloc_refill(cachep, flags);
> >         }
> > +       memleak_erase(&ac->entry[ac->avail]);
> >         return objp;
> >  }
>
> Can't we tell the GC not to scan any of the array cache structs? You
> could put that in alloc_arraycache(), I think.

Yes, we can. I'll give it a try before updating the patches.

> > @@ -3209,7 +3211,11 @@ static void __cache_free(struct kmem_cac
> >   */
> >  void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
> >  {
> > -       return __cache_alloc(cachep, flags, __builtin_return_address(0));
> > +       void *ptr = __cache_alloc(cachep, flags, __builtin_return_address(0));
> > +
> > +       memleak_alloc(ptr, obj_size(cachep), 1);
>
> Can you move memleak_alloc() call to __cache_alloc() instead to avoid
> duplication?

It might clutter the code because __cache_alloc is used by kmalloc as
well and the exact size information is lost. It would be to
explicitely give the type information to kmemleak in kmalloc and have
memleak_alloc called in __cache_alloc (with slight overhead of calling
kmemleak functions twice). The other option is to pass an extra
argument (guessed typeid) to __cache_alloc but this means adding extra
ifdefs.

Thanks.

--
Catalin
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