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    SubjectRe: SLUB: Return ZERO_SIZE_PTR for kmalloc(0)
    [Pekka Enberg - Mon, Jun 04, 2007 at 07:37:01PM +0300]
    | On 6/4/07, Linus Torvalds <torvalds@linux-foundation.org> wrote:
    | >Well, the red-zones won't catch readers, and more importantly, even for
    | >writers they are *really* inconvenient, because it will just tell you
    | >something bad happened, it won't tell you *where* it happened.
    |
    | True.
    |
    | On 6/4/07, Linus Torvalds <torvalds@linux-foundation.org> wrote:
    | >Since comparing the addresses of two zero-sized allocations is insane and
    | >not done _anyway_, it's just much better to return an invalid address.
    |
    | Then we might as well return your regular NULL pointer for zero-length
    | allocations as you can't do anything sane with ZERO_SIZE_PTR either.

    Hi Pekka,

    you know, I'm absolutely agree with you. Hey, kernel hackers don't blame
    me ;). But lets just take an example from a real life: I'm asking for
    someone to give me 50 cents he would probably give me this. But if I'm
    asking someone to give me 0 cents - he''ll give me nothing!!! Nobody
    giving me a spec. papper on which "zero cents" is written. :)
    So the code

    p = kmalloc(0);
    if (!p) {
    return -ENOMEM;
    }

    is absolutely right - we physically have _no_ zero-sized memory. And as result
    we have no reason to keep spec. slab to track zero-sized allocs.

    Please, don't get me wrong, I'm not a kernel specialist...
    And sorry for meddling into coversation.

    Cyrill

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