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    Subject[PATCHv3 02/17] mm/khugepaged: Do not collapse pages in encrypted VMAs
    Date
    Pages for encrypted VMAs have to be allocated in a special way:
    we would need to propagate down not only desired NUMA node but also
    whether the page is encrypted.

    It complicates not-so-trivial routine of huge page allocation in
    khugepaged even more. It also puts more pressure on page allocator:
    we cannot re-use pages allocated for encrypted VMA to collapse
    page in unencrypted one or vice versa.

    I think for now it worth skipping encrypted VMAs. We can return
    to this topic later.

    Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
    ---
    include/linux/mm.h | 7 +++++++
    mm/khugepaged.c | 2 ++
    2 files changed, 9 insertions(+)

    diff --git a/include/linux/mm.h b/include/linux/mm.h
    index 1c3c15f37ed6..435b053c457c 100644
    --- a/include/linux/mm.h
    +++ b/include/linux/mm.h
    @@ -1492,6 +1492,13 @@ static inline bool vma_is_anonymous(struct vm_area_struct *vma)
    return !vma->vm_ops;
    }

    +#ifndef vma_is_encrypted
    +static inline bool vma_is_encrypted(struct vm_area_struct *vma)
    +{
    + return false;
    +}
    +#endif
    +
    #ifndef vma_keyid
    static inline int vma_keyid(struct vm_area_struct *vma)
    {
    diff --git a/mm/khugepaged.c b/mm/khugepaged.c
    index d7b2a4bf8671..a03b40bef033 100644
    --- a/mm/khugepaged.c
    +++ b/mm/khugepaged.c
    @@ -835,6 +835,8 @@ static bool hugepage_vma_check(struct vm_area_struct *vma)
    return false;
    if (is_vma_temporary_stack(vma))
    return false;
    + if (vma_is_encrypted(vma))
    + return false;
    return !(vma->vm_flags & VM_NO_KHUGEPAGED);
    }

    --
    2.17.1
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