linux-kernel - [PATCH v2 3/3] mm: mmap: cleanup code that preserves special vm_page

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Date:	Sat, 23 Aug 2014 18:12:01 -0400
From:	Peter Feiner <pfeiner@...gle.com>
To:	linux-mm@...ck.org
Cc:	linux-kernel@...r.kernel.org, Peter Feiner <pfeiner@...gle.com>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	Pavel Emelyanov <xemul@...allels.com>,
	Jamie Liu <jamieliu@...gle.com>,
	Hugh Dickins <hughd@...gle.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH v2 3/3] mm: mmap: cleanup code that preserves special vm_page_prot bits

Replace logic that has been factored out into a utility method.

Signed-off-by: Peter Feiner <pfeiner@...gle.com>
---
 mm/mmap.c | 16 ++--------------
 1 file changed, 2 insertions(+), 14 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index abcac32..c18c49a 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1618,20 +1618,8 @@ munmap_back:
 			goto free_vma;
 	}
 
-	if (vma_wants_writenotify(vma)) {
-		pgprot_t pprot = vma->vm_page_prot;
-
-		/* Can vma->vm_page_prot have changed??
-		 *
-		 * Answer: Yes, drivers may have changed it in their
-		 *         f_op->mmap method.
-		 *
-		 * Ensures that vmas marked as uncached stay that way.
-		 */
-		vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
-		if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
-			vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
-	}
+	if (vma_wants_writenotify(vma))
+		vma_enable_writenotify(vma);
 
 	vma_link(mm, vma, prev, rb_link, rb_parent);
 	/* Once vma denies write, undo our temporary denial count */
-- 
2.1.0.rc2.206.gedb03e5

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