The patch titled
Subject: mm, dax: VMA with vm_ops->pfn_mkwrite wants to be write-notified
has been added to the -mm tree. Its filename is
mm-dax-vma-with-vm_ops-pfn_mkwrite-wants-to-be-write-notified.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-dax-vma-with-vm_ops-pfn_mkwrite-wants-to-be-write-notified.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-dax-vma-with-vm_ops-pfn_mkwrite-wants-to-be-write-notified.patch
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From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Subject: mm, dax: VMA with vm_ops->pfn_mkwrite wants to be write-notified
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.
A theoretical scenario that will cause these missed events is:
On writable mapping with vm_ops->pfn_mkwrite, but without
vm_ops->page_mkwrite: read fault followed by write access to the pfn.
Writable pte will be set up on read fault and write fault will not be
generated.
I found it examining Dave's complaint on generic/080:
http://lkml.kernel.org/g/20150831233803.GO3902@dastard
Although I don't think it's the reason.
It shouldn't be a problem for ext2/ext4 as they provide both pfn_mkwrite
and page_mkwrite.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Yigal Korman <yigal@xxxxxxxxxxxxx>
Acked-by: Boaz Harrosh <boaz@xxxxxxxxxxxxx>
Cc: Matthew Wilcox <matthew.r.wilcox@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff -puN mm/mmap.c~mm-dax-vma-with-vm_ops-pfn_mkwrite-wants-to-be-write-notified mm/mmap.c
--- a/mm/mmap.c~mm-dax-vma-with-vm_ops-pfn_mkwrite-wants-to-be-write-notified
+++ a/mm/mmap.c
@@ -1498,7 +1498,8 @@ int vma_wants_writenotify(struct vm_area
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
_
Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
mm-dax-vma-with-vm_ops-pfn_mkwrite-wants-to-be-write-notified.patch
mm-drop-page-slab_page.patch
slab-slub-use-page-rcu_head-instead-of-page-lru-plus-cast.patch
zsmalloc-use-page-private-instead-of-page-first_page.patch
mm-pack-compound_dtor-and-compound_order-into-one-word-in-struct-page.patch
mm-make-compound_head-robust.patch
mm-use-unsigned-int-for-page-order.patch
mm-use-unsigned-int-for-compound_dtor-compound_order-on-64bit.patch
page-flags-trivial-cleanup-for-pagetrans-helpers.patch
page-flags-introduce-page-flags-policies-wrt-compound-pages.patch
page-flags-define-pg_locked-behavior-on-compound-pages.patch
page-flags-define-behavior-of-fs-io-related-flags-on-compound-pages.patch
page-flags-define-behavior-of-lru-related-flags-on-compound-pages.patch
page-flags-define-behavior-slb-related-flags-on-compound-pages.patch
page-flags-define-behavior-of-xen-related-flags-on-compound-pages.patch
page-flags-define-pg_reserved-behavior-on-compound-pages.patch
page-flags-define-pg_swapbacked-behavior-on-compound-pages.patch
page-flags-define-pg_swapcache-behavior-on-compound-pages.patch
page-flags-define-pg_mlocked-behavior-on-compound-pages.patch
page-flags-define-pg_uncached-behavior-on-compound-pages.patch
page-flags-define-pg_uptodate-behavior-on-compound-pages.patch
page-flags-look-on-head-page-if-the-flag-is-encoded-in-page-mapping.patch
mm-sanitize-page-mapping-for-tail-pages.patch
mm-support-madvisemadv_free-fix-3.patch
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