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    SubjectRe: [git pull] m68k SLUB fix for 2.6.39
    On Tue, 3 May 2011, David Rientjes wrote:

    > So we're in the unfortunate position where slub works fine for some
    > architectures with DISCONTIGMEM and not with others. It seems like the
    > problems originating on James' hppa aren't related to slab allocation at
    > all, though, so I'm wondering if we should rethink disallowing SLUB as it
    > sits in Linus' tree right now for everything that uses DISCONTINGMEM
    > without NUMA and not force them to enable CONFIG_BROKEN?
    >
    > Perhaps change the kconfig entry to only block slub for parisc instead?

    As i have explained multiple times before: This is a generic issue with a
    kernel configuration that has DISCONTIGMEM on and NUMA configured off.
    Core code in various subsystems makes various assumptions in the !NUMA
    case. F.e. page_to_nid(page) == 0. Slub is one of them.

    DISCONTIGMEM works fine on !NUMA if it just has a single node which is 0.
    But in James' hppa we have multiple nodes and thus a fundamental problem
    with node 1 existing in a non NUMA environment. We then have a strange
    mixture of NUMA nodes existing in DISCONTIGMEM code and the core code
    assuming there are none. This can lead to numerous weird problems.

    IMHO A config broken for DISCONTIG and !NUMA for arches that can actually
    use multiple DISCONTIG nodes would be the proper thing.



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