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

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Date:	Wed,  8 Dec 2010 23:49:39 -0800
From:	Michel Lespinasse <walken@...gle.com>
To:	Nick Piggin <npiggin@...nel.dk>, linux-mm@...ck.org
Cc:	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 68f2dbe..7befd03 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3015,12 +3015,6 @@ 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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