From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id 6791B6B0087 for ; Wed, 8 Dec 2010 02:02:31 -0500 (EST) Received: from m2.gw.fujitsu.co.jp ([10.0.50.72]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id oB872RAn030478 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Wed, 8 Dec 2010 16:02:27 +0900 Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 6371745DEE2 for ; Wed, 8 Dec 2010 16:02:27 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 3D99845DEDD for ; Wed, 8 Dec 2010 16:02:27 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 249E8E08001 for ; Wed, 8 Dec 2010 16:02:27 +0900 (JST) Received: from ml14.s.css.fujitsu.com (ml14.s.css.fujitsu.com [10.249.87.104]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id DA3B21DB803E for ; Wed, 8 Dec 2010 16:02:26 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [merged] mm-mempolicyc-add-rcu-read-lock-to-protect-pid-structure.patch removed from -mm tree In-Reply-To: <201012071948.oB7Jm78B004585@imap1.linux-foundation.org> References: <201012071948.oB7Jm78B004585@imap1.linux-foundation.org> Message-Id: <20101208160009.173F.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable Date: Wed, 8 Dec 2010 16:02:26 +0900 (JST) Sender: owner-linux-mm@kvack.org To: akpm@linux-foundation.org Cc: kosaki.motohiro@jp.fujitsu.com, zengzm.kernel@gmail.com, cl@linux-foundation.org, paulmck@us.ibm.com, mm-commits@vger.kernel.org, Peter Zijlstra , LKML , linux-mm List-ID: >=20 > The patch titled > mm/mempolicy.c: add rcu read lock to protect pid structure > has been removed from the -mm tree. Its filename was > mm-mempolicyc-add-rcu-read-lock-to-protect-pid-structure.patch >=20 > This patch was dropped because it was merged into mainline or a subsystem= tree >=20 > The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmot= m/ >=20 > ------------------------------------------------------ > Subject: mm/mempolicy.c: add rcu read lock to protect pid structure > From: Zeng Zhaoming >=20 > find_task_by_vpid() should be protected by rcu_read_lock(), to prevent > free_pid() reclaiming pid. >=20 > Signed-off-by: Zeng Zhaoming > Cc: "Paul E. McKenney" > Cc: KOSAKI Motohiro > Cc: Christoph Lameter > Signed-off-by: Andrew Morton Andrew, please consider pick following patch too. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =46rom 9de9f70f74e55d92b5e9057e22fc629405f63295 Mon Sep 17 00:00:00 2001 From: KOSAKI Motohiro Date: Thu, 16 Dec 2010 17:49:23 +0900 Subject: [PATCH] mempolicy: remove tasklist_lock from migrate_pages Today, tasklist_lock in migrate_pages doesn't protect anything.=20 rcu_read_lock() provide enough protection from pid hash walk. Reported-by: Peter Zijlstra Cc: Christoph Lameter Signed-off-by: KOSAKI Motohiro --- mm/mempolicy.c | 3 --- 1 files changed, 0 insertions(+), 3 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 11ff260..9064945 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1308,16 +1308,13 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned= long, maxnode, =20 /* Find the mm_struct */ rcu_read_lock(); - read_lock(&tasklist_lock); task =3D pid ? find_task_by_vpid(pid) : current; if (!task) { - read_unlock(&tasklist_lock); rcu_read_unlock(); err =3D -ESRCH; goto out; } mm =3D get_task_mm(task); - read_unlock(&tasklist_lock); rcu_read_unlock(); =20 err =3D -EINVAL; --=20 1.6.5.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org