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 ESMTP id 1A0366B007B for ; Thu, 2 Jun 2011 17:24:25 -0400 (EDT) Date: Thu, 2 Jun 2011 14:23:48 -0700 From: Chris Wright Subject: Re: [PATCH] ksm: fix race between ksmd and exiting task Message-ID: <20110602212348.GM23047@sequoia.sous-sol.org> References: <20110601222032.GA2858@thinkpad> <2144269697.363041.1306998593180.JavaMail.root@zmail06.collab.prod.int.phx2.redhat.com> <20110602141927.GA2011@thinkpad> <20110602164841.GK23047@sequoia.sous-sol.org> <20110602173549.GL23047@sequoia.sous-sol.org> <20110602201236.GB4114@thinkpad> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110602201236.GB4114@thinkpad> Sender: owner-linux-mm@kvack.org List-ID: To: Andrea Righi Cc: Chris Wright , CAI Qian , Hugh Dickins , Andrea Arcangeli , Rik van Riel , Mel Gorman , Izik Eidus , KAMEZAWA Hiroyuki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton * Andrea Righi (andrea@betterlinux.com) wrote: > On Thu, Jun 02, 2011 at 10:35:49AM -0700, Chris Wright wrote: > > Andrea Righi reported a case where an exiting task can race against > > ksmd. > > > > ksm_scan.mm_slot == the only registered mm > > CPU 1 (bug program) CPU 2 (ksmd) > > list_empty() is false > > lock > > ksm_scan.mm_slot > > list_del > > unlock > > slot == &ksm_mm_head (but list is now empty_) > > > > Close this race by revalidating that the new slot is not simply the list > > head again. > > I confirm this fixes the problem on my side. > > Tested-by: Andrea Righi Great, thanks for verifying. thanks, -chris -- 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 internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org