+ mm-fix-lazyfree-bug-on-check-in-try_to_unmap_one.patch added to -mm tree

+ mm-fix-lazyfree-bug-on-check-in-try_to_unmap_one.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm: fix lazyfree BUG_ON check in try_to_unmap_one()
has been added to the -mm tree.  Its filename is
     mm-fix-lazyfree-bug-on-check-in-try_to_unmap_one.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-fix-lazyfree-bug-on-check-in-try_to_unmap_one.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-fix-lazyfree-bug-on-check-in-try_to_unmap_one.patch

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*** Remember to use Documentation/SubmitChecklist when testing your code ***

The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Minchan Kim <minchan@kernel.org>
Subject: mm: fix lazyfree BUG_ON check in try_to_unmap_one()

If a page is swapbacked, it means it should be in swapcache in
try_to_unmap_one's path.

If a page is !swapbacked, it mean it shouldn't be in swapcache in
try_to_unmap_one's path.

Check both two cases all at once and if it fails, warn and return
SWAP_FAIL.  Such bug never mean we should shut down the kernel.

Link: http://lkml.kernel.org/r/20170307055551.GC29458@bbox
Signed-off-by: Minchan Kim <minchan@kernel.org>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shaohua Li <shli@fb.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/rmap.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff -puN mm/rmap.c~mm-fix-lazyfree-bug-on-check-in-try_to_unmap_one mm/rmap.c
--- a/mm/rmap.c~mm-fix-lazyfree-bug-on-check-in-try_to_unmap_one
+++ a/mm/rmap.c
@@ -1413,8 +1413,13 @@ static int try_to_unmap_one(struct page
 			 * Store the swap location in the pte.
 			 * See handle_pte_fault() ...
 			 */
-			VM_BUG_ON_PAGE(!PageSwapCache(page) && PageSwapBacked(page),
-				page);
+			if (VM_WARN_ON_ONCE(PageSwapBacked(page) !=
+						PageSwapCache(page))) {
+				ret = SWAP_FAIL;
+				page_vma_mapped_walk_done(&pvmw);
+				break;
+
+			}
 
 			/* MADV_FREE page check */
 			if (!PageSwapBacked(page)) {
_

Patches currently in -mm which might be from minchan@kernel.org are

mm-reclaim-madv_free-pages-fix.patch
mm-fix-lazyfree-bug-on-check-in-try_to_unmap_one.patch