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    SubjectRe: Signal 11 - the continuing saga
    On Wed, 13 Dec 2000, Linus Torvalds wrote:

    > On Wed, 13 Dec 2000, Linus Torvalds wrote:
    > >
    > > Hint: "ptep_mkdirty()".

    <g> rather obvious oopsie.. once spotted.

    > In case you wonder why the bug was so insidious, what this caused was two
    > separate problems, both of them able to cause SIGSGV's.
    >
    > One: we didn't mark the page table entry dirty like we were supposed to.
    >
    > Two: by making it writable, we also made the page shared, even if it
    > wasn't supposed to be shared (so when the next process wrote to the page,
    > if the swap page was shared with somebody else, the changes would show up
    > even in the process that _didn't_ write to it).
    >
    > And "ptep_mkdirty()" is only used by swapoff, so nothing else would show
    > this. Which was why it hadn't been immediately obvious that anything was
    > broken.

    The terminal OOM problem is now gone and I haven't seen a SIGSEGV yet
    running virgin source.

    IOU 5 bogo$$

    -Mike

    (I still see something with IKD that _could_ be timing related troubles.
    There are a couple of grubby fingerprints I need to wipe off, and some
    churn/burn hours to be sure)

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