linux-kernel - [PATCH 1/9] mm: make mlockall preserve flags other than VM_LOCKED in def

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Message-Id: <1356050997-2688-2-git-send-email-walken@google.com>
Date:	Thu, 20 Dec 2012 16:49:49 -0800
From:	Michel Lespinasse <walken@...gle.com>
To:	Andy Lutomirski <luto@...capital.net>,
	Ingo Molnar <mingo@...nel.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Hugh Dickins <hughd@...gle.com>, Jorn_Engel <joern@...fs.org>,
	Rik van Riel <riel@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/9] mm: make mlockall preserve flags other than VM_LOCKED in def_flags

On most architectures, def_flags is either 0 or VM_LOCKED depending on
whether mlockall(MCL_FUTURE) was called. However, this is not an absolute
rule as kvm support on s390 may set the VM_NOHUGEPAGE flag in def_flags.
We don't want mlockall to clear that.

Signed-off-by: Michel Lespinasse <walken@...gle.com>

---
 mm/mlock.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/mlock.c b/mm/mlock.c
index f0b9ce572fc7..a2ee45c030fa 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -517,10 +517,11 @@ SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
 static int do_mlockall(int flags)
 {
 	struct vm_area_struct * vma, * prev = NULL;
-	unsigned int def_flags = 0;
+	unsigned int def_flags;
 
+	def_flags = current->mm->def_flags & ~VM_LOCKED;
 	if (flags & MCL_FUTURE)
-		def_flags = VM_LOCKED;
+		def_flags |= VM_LOCKED;
 	current->mm->def_flags = def_flags;
 	if (flags == MCL_FUTURE)
 		goto out;
-- 
1.7.7.3
--
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