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Subject[PATCHv2 05/14] 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 6c50f77c75d5..b6a72eb82f4b 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1479,6 +1479,13 @@ 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 e42568284e06..42f33fd526a0 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);
}

--
2.16.2
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