Re: [uml-devel] [PATCH 5/6] slab: Annotate slab

From: Pekka Enberg
Date: Wed Sep 03 2008 - 05:41:27 EST


On Wed, Sep 3, 2008 at 12:27 PM, Pekka Enberg <penberg@xxxxxxxxxxxxxx> wrote:
> On Wed, Sep 3, 2008 at 8:08 AM, Steve VanDeBogart
> <vandebo-lkml@xxxxxxxxxxx> wrote:
>> Ideally, we'd tell Valgrind that the bytes of a free'd slab object are
>> no longer accessible, but the initialized state should remain the same
>> until the object is made accessible again by the next allocation of
>> the object. Unfortunately, the compression method for A & V bits in
>> Valgrind doesn't allow a region to be inaccessible and retain validness
>> bits.
>
> I don't see why you should mark them initialized all the time. Just
> mark them as uninitialized on kmem_cache_free() and again as
> initialized when they're about to be returned from kmem_cache_alloc()
> like we do in kmemcheck.

Btw, actually, we don't mark them as uninitialized at the moment, but
that's a bug in kmemcheck.
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