linux-kernel - [PATCH] mm: softdirty: keep bit when zapping file pte

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Date:	Sat, 20 Sep 2014 01:03:07 -0700
From:	Peter Feiner <pfeiner@...gle.com>
To:	linux-mm@...ck.org
Cc:	linux-kernel@...r.kernel.org,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	Pavel Emelyanov <xemul@...allels.com>,
	Jamie Liu <jamieliu@...gle.com>,
	Hugh Dickins <hughd@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Feiner <pfeiner@...gle.com>
Subject: [PATCH] mm: softdirty: keep bit when zapping file pte

Fixes the same bug as b43790eedd31e9535b89bbfa45793919e9504c34 and
9aed8614af5a05cdaa32a0b78b0f1a424754a958 where the return value of
pte_*mksoft_dirty was being ignored.

To be sure that no other pte/pmd "mk" function return values were
being ignored, I annotated the functions in
arch/x86/include/asm/pgtable.h with __must_check and rebuilt.

Signed-off-by: Peter Feiner <pfeiner@...gle.com>
---
 mm/memory.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memory.c b/mm/memory.c
index adeac30..fc46934 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1125,7 +1125,7 @@ again:
 						addr) != page->index) {
 				pte_t ptfile = pgoff_to_pte(page->index);
 				if (pte_soft_dirty(ptent))
-					pte_file_mksoft_dirty(ptfile);
+					ptfile = pte_file_mksoft_dirty(ptfile);
 				set_pte_at(mm, addr, pte, ptfile);
 			}
 			if (PageAnon(page))
-- 
2.1.0.rc2.206.gedb03e5

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