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    SubjectRe: IA64 non-contiguous memory space bugs
    I'm only following this superficially, but keep in mind that a vm-area
    MUST NEVER cross a hole.

    --david

    On 2/21/06, Chen, Kenneth W <kenneth.w.chen@intel.com> wrote:
    > David Gibson wrote on Tuesday, February 21, 2006 4:14 PM
    > > First bug (confirmed many months ago by Chris Wedgwood) - you can get
    > > weird effects if you attempt to mmap() something into one of the
    > > address space gaps. The ia64 outer wrapper for mmap2() tries to
    > > prevent it, but doesn't do a good enough job, it's still possible
    > > indirectly with shmat() and maybe mremap(). Basic trouble is that
    > > most of the checks applied by the generic code assume that everything
    > > between 0 and TASK_SIZE is valid.
    >
    > Ha ha ha.
    >
    > On ia64, the low level tlb fault handler (vhpt_miss and nested_dtlb_miss)
    > checks that all unused address bits (between REGION_NUMBER and PGDIR_SHIFT)
    > should be all zero. If they are not zero, it will fall into page fault
    > handler and in there, ia64 should just send SEGV instead of happily hand
    > over a page. Buggy buggy....
    >
    > - Ken
    >
    > -
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