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    SubjectRe: BUG: unable to handle kernel paging request at ffffc7ff81000398 (sys_kexec_load)
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    On Sat, 2012-01-21 at 20:49 -0800, Eric W. Biederman wrote:
    > Interesting.
    >
    > The fact that this happens in native_set_pte would suggest that we are
    > trying to write to a page table that does not exist. So this might
    > be a layer below kexec_load that has the problem.
    >
    > Do you have the kernel you were testing? A disassembly of the
    > native_set_pte, machine_kexec_prepare and sys_kexec_load
    > would be interesting, for attempting to trace this back to what went
    > wrong.

    I did some work into investigating it today, looks like it's simple to trigger it using the following code:

    #include <fcntl.h>
    int main(void)
    {
    char dummy[4096] = {0};
    syscall(246, 0xffffffff81008000, 1, dummy, 2);
    return 0;
    }

    I'll continue trying to figure out whats wrong, but hopefully this lead will help in reproducing it easily.

    --

    Sasha.



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