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    SubjectRe: [PATCHv2 2/6] x86, mpx: do not set ->vm_ops on mpx VMAs
    On Fri, 17 Jul 2015 14:53:09 +0300 "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> wrote:

    > MPX setups private anonymous mapping, but uses vma->vm_ops too.
    > This can confuse core VM, as it relies on vm->vm_ops to distinguish
    > file VMAs from anonymous.
    >
    > As result we will get SIGBUS, because handle_pte_fault() thinks it's
    > file VMA without vm_ops->fault and it doesn't know how to handle the
    > situation properly.
    >
    > Let's fix that by not setting ->vm_ops.
    >
    > We don't really need ->vm_ops here: MPX VMA can be detected with VM_MPX
    > flag. And vma_merge() will not merge MPX VMA with non-MPX VMA, because
    > ->vm_flags won't match.
    >
    > The only thing left is name of VMA. I'm not sure if it's part of ABI, or
    > we can just drop it. The patch keep it by providing arch_vma_name() on x86.
    >
    > Build tested only.

    mpx.c has changed.

    arch/x86/mm/mpx.c: In function 'try_unmap_single_bt':
    arch/x86/mm/mpx.c:930: error: implicit declaration of function 'is_mpx_vma'

    I'll drop this patch and see what happens.


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