linux-kernel - [PATCH 2/2] mlock: do not munlock pages in __do

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Message-Id: <1297126056-14322-3-git-send-email-walken@google.com>
Date:	Mon,  7 Feb 2011 16:47:36 -0800
From:	Michel Lespinasse <walken@...gle.com>
To:	linux-mm@...ck.org, Lee Schermerhorn <lee.schermerhorn@...com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Hugh Dickins <hughd@...gle.com>,
	Rik van Riel <riel@...hat.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] mlock: do not munlock pages in __do_fault()

If the page is going to be written to, __do_page needs to break COW.
However, the old page (before breaking COW) was never mapped mapped into
the current pte (__do_fault is only called when the pte is not present),
so vmscan can't have marked the old page as PageMlocked due to being
mapped in __do_fault's VMA. Therefore, __do_fault() does not need to worry
about clearing PageMlocked() on the old page.

Signed-off-by: Michel Lespinasse <walken@...gle.com>
---
 mm/memory.c |    6 ------
 1 files changed, 0 insertions(+), 6 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 32df03c..8e8c1832 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3051,12 +3051,6 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 				goto out;
 			}
 			charged = 1;
-			/*
-			 * Don't let another task, with possibly unlocked vma,
-			 * keep the mlocked page.
-			 */
-			if (vma->vm_flags & VM_LOCKED)
-				clear_page_mlock(vmf.page);
 			copy_user_highpage(page, vmf.page, address, vma);
 			__SetPageUptodate(page);
 		} else {
-- 
1.7.3.1
--
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