thp: export maybe_mkwrite
huge_memory.c needs it too when it fallbacks in copying hugepages into
regular fragmented pages if hugepage allocation fails during COW.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/mm.h b/include/linux/mm.h
index a2718e1..6bef67d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -430,6 +430,19 @@
}
/*
+ * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when
+ * servicing faults for write access. In the normal case, do always want
+ * pte_mkwrite. But get_user_pages can cause write faults for mappings
+ * that do not have writing enabled, when used by access_process_vm.
+ */
+static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
+{
+ if (likely(vma->vm_flags & VM_WRITE))
+ pte = pte_mkwrite(pte);
+ return pte;
+}
+
+/*
* Multiple processes may "see" the same page. E.g. for untouched
* mappings of /dev/null, all processes see the same page full of
* zeroes, and text pages of executables and shared libraries have