+ mm-do-not-access-page-mapping-directly-on-page_endio.patch added to -mm tree

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The patch titled
     Subject: mm: do not access page->mapping directly on page_endio
has been added to the -mm tree.  Its filename is
     mm-do-not-access-page-mapping-directly-on-page_endio.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-do-not-access-page-mapping-directly-on-page_endio.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-do-not-access-page-mapping-directly-on-page_endio.patch

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------------------------------------------------------
From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: mm: do not access page->mapping directly on page_endio

With rw_page, page_endio is used for completing IO on a page and it
propagates write error to the address space if the IO fails.  The problem
is it accesses page->mapping directly which might be okay for file-backed
pages but it shouldn't for anonymous page.  Otherwise, it can corrupt one
of field from anon_vma under us and system goes panic randomly.

Link: http://lkml.kernel.org/r/1487741964-17913-1-git-send-email-minchan@xxxxxxxxxx
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 mm/filemap.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff -puN mm/filemap.c~mm-do-not-access-page-mapping-directly-on-page_endio mm/filemap.c
--- a/mm/filemap.c~mm-do-not-access-page-mapping-directly-on-page_endio
+++ a/mm/filemap.c
@@ -1008,9 +1008,12 @@ void page_endio(struct page *page, bool
 		unlock_page(page);
 	} else {
 		if (err) {
+			struct address_space *mapping;
+
 			SetPageError(page);
-			if (page->mapping)
-				mapping_set_error(page->mapping, err);
+			mapping = page_mapping(page);
+			if (mapping)
+				mapping_set_error(mapping, err);
 		}
 		end_page_writeback(page);
 	}
_

Patches currently in -mm which might be from minchan@xxxxxxxxxx are

mm-swap-add-cluster-lock-v5-fix.patch
zram-remove-waitqueue-for-io-done.patch
zram-extend-zero-pages-to-same-element-pages-fix.patch
mm-do-not-access-page-mapping-directly-on-page_endio.patch




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