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    SubjectRe: [BUG] SLOB breaks Crypto
    Matt Mackall schrieb:
    > On Mon, 2010-05-17 at 23:50 +0200, Adrian-Ken Rueegsegger wrote:
    >> Geert Uytterhoeven wrote:
    >>> On Fri, Mar 19, 2010 at 02:33, Herbert Xu <herbert@gondor.apana.org.au> wrote:
    >>>> On Thu, Mar 18, 2010 at 10:24:41PM +0100, michael-dev@fami-braun.de wrote:
    >>>>> Pekka Enberg schrieb:
    >>>>>> Even with CONFIG_DEBUG_SLAB enabled or with CONFIG_SLUB and
    >>>>>> CONFIG_SLUB_DEBUG_ON?
    >>>>> no, these options have not been / are not enabled.
    >>>> Can you please try it with those options enabled? That will tell
    >>>> us if there is some latent bug in the crypto layer that only shows
    >>>> up right away under SLOB.
    >>> After seeing a posting from Nemoto-san on the linux-mips list (should
    >>> show up soon on
    >>> http://www.linux-mips.org/archives/linux-mips/2010-05/threads.html),
    >>> I'm wondering if these defaults are the culprit;
    >>>
    >>> mm/slab.c:#define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
    >>> mm/slob.c:#define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long)
    >>> mm/slub.c:#define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
    >
    > Seems the target here is x86, which has no DMA or other alignment
    > constraints.
    >
    >> Just a quick note: I changed this line in mm/slob.c to (unsigned long
    >> long) and was able to load tcrypt without the kernel oopsing or
    >> panic'ing. When running all test via
    >>
    >> modprobe tcrypt
    >
    > Hmmm, sounds like something in crypto has a bogus alignment/padding
    > expectation. Surprised it wasn't caught by SLAB redzoning though.
    > Perhaps we can 'bisect' the test suite to narrow it down to a particular
    > test. Alternately, we can tweak SLAB to offset buffers by two bytes and
    > see what breaks.

    As noted in my other mail [1] it seems like the HMAC tests trigger these
    errors.

    Regards,
    Adrian

    [1] - http://lkml.org/lkml/2010/5/14/199


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