On Fri, 1 Jun 2007, Christoph Lameter wrote:
>
> Instead of returning the smallest available object return ZERO_SIZE_PTR.

Ok, I just noticed that this still has a bug: not just kfree(), but 
krealloc() needs to treat ZERO_SIZE_PTR properly.

Your patch introduces two bugs in mm/slub.c:krealloc():

 - The

        if (unlikely(!p))
                return kmalloc(new_size, flags);

   test needs to be for NULL or ZERO_SIZE_PTR. Otherwise it will oops in 
   ksize(p), I think.

 - And the

        if (unlikely(!new_size)) {
                kfree(p);
                return NULL;
        }

   thing should logically return ZERO_SIZE_PTR instead of NULL.

So basically

        krealloc(kmalloc(0), n, flags);

must work, and

        krealloc(old, 0, flags)

should return a zero-sized allocation.

I'd forgotten about krealloc(), because that whole concept is fairly new.

                Linus
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