[PATCH] mm, dax: VMA with vm_ops->pfn_mkwrite wants to be write-notified

From: Kirill A. Shutemov
Date: Tue Sep 01 2015 - 06:22:55 EST

For VM_PFNMAP and VM_MIXEDMAP we use vm_ops->pfn_mkwrite instead of
vm_ops->page_mkwrite to notify abort write access. This means we want
vma->vm_page_prot to be write-protected if the VMA provides this vm_ops.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Yigal Korman <yigal@xxxxxxxxxxxxx>
Cc: Boaz Harrosh <boaz@xxxxxxxxxxxxx>
Cc: Matthew Wilcox <matthew.r.wilcox@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
mm/mmap.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index df6d5f07035b..3f78bceefe5a 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1498,7 +1498,8 @@ int vma_wants_writenotify(struct vm_area_struct *vma)
return 0;

/* The backer wishes to know when pages are first written to? */
- if (vma->vm_ops && vma->vm_ops->page_mkwrite)
+ if (vma->vm_ops &&
+ (vma->vm_ops->page_mkwrite || vma->vm_ops->pfn_mkwrite))
return 1;

/* The open routine did something to the protections that pgprot_modify

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