From c3d16e16522fe3fe8759735850a0676da18f4b1d Mon Sep 17 00:00:00 2001
From: Cyrill Gorcunov <gorcunov@gmail.com>
Date: Wed, 16 Oct 2013 13:46:51 -0700
Subject: mm: migration: do not lose soft dirty bit if page is in migration
 state

If page migration is turned on in config and the page is migrating, we
may lose the soft dirty bit.  If fork and mprotect are called on
migrating pages (once migration is complete) pages do not obtain the
soft dirty bit in the correspond pte entries.  Fix it adding an
appropriate test on swap entries.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/migrate.c | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'mm/migrate.c')

diff --git a/mm/migrate.c b/mm/migrate.c
index a26bccd44ccb..7a7325ee1d08 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -161,6 +161,8 @@ static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
 
 	get_page(new);
 	pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
+	if (pte_swp_soft_dirty(*ptep))
+		pte = pte_mksoft_dirty(pte);
 	if (is_write_migration_entry(entry))
 		pte = pte_mkwrite(pte);
 #ifdef CONFIG_HUGETLB_PAGE
-- 
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