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    SubjectRe: Split 'flush_old_exec' into two functions - 221af7f87b97431e3ee21ce4b0e77d5411cf1549

    On Mon, 1 Feb 2010, Michal Simek wrote:
    > Hi Peter and Linus,
    > commit 221af7f87b97431e3ee21ce4b0e77d5411cf1549 breaks anything on Microblaze.

    Gaah. My original version of that patch very much tried to make it a no-op
    semantically, but then Peter made some preparatory changes for the next
    patch, so it actually changes semantics a bit. I was expecting that to be
    benign, but clearly there are issues.

    > None reported any problem that's why I think that is Microblaze related.

    Well, our previous handling of the critical stage of 'execve()' when we
    actually switch from the old process to the new was _so_ grotty that many
    architectures ended up playing some really subtle games there. The whole
    point of the patch is to get rid of the games, but it's entirely possible
    that Microblaze (and others) had crazy things going on that broke when we
    made the ordering more straightforward.

    That said, Microblaze is not one of the architectures I would have
    expected to have problems. It has one of the most straightforward
    "flush_thread()" implementations in the whole kernel (it's a no-op ;), and
    that's where most of the hacky things were for the architectures that
    needed the change. And it has no "arch_pick_mmap_layout()" issues or
    anything else that tends to depend on personality bits or whatever.

    Microblaze is a no-MMU platform, isn't it? Which binary format does it
    use? It looks like _some_ binaries work (it seems to happily be running a
    shell to actually do those startup scripts) while others have problems. Is
    there a difference between "/bin/sh" and the binaries that seem to be
    problematic (like /bin/mount and /bin/ifup).

    Are the failing binaries all setuid ones, for example? Or shared vs
    non-shared? Or ELF vs FLAT or whatever?


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