From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934379AbXGQRvS (ORCPT ); Tue, 17 Jul 2007 13:51:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759633AbXGQRvJ (ORCPT ); Tue, 17 Jul 2007 13:51:09 -0400 Received: from smtp2.linux-foundation.org ([207.189.120.14]:42069 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759515AbXGQRvI (ORCPT ); Tue, 17 Jul 2007 13:51:08 -0400 Date: Tue, 17 Jul 2007 10:49:36 -0700 (PDT) From: Linus Torvalds To: Ingo Molnar cc: Olaf Kirch , Jarek Poplawski , linux-kernel@vger.kernel.org, davem@davemloft.net Subject: Re: [patch] revert: [NET]: Fix races in net_rx_action vs netpoll In-Reply-To: <20070717085748.GA32114@elte.hu> Message-ID: References: <20070716091236.GA10718@elte.hu> <20070717061458.GB1640@ff.dom.local> <200707170955.38536.olaf.kirch@oracle.com> <200707171028.36451.olaf.kirch@oracle.com> <20070717085748.GA32114@elte.hu> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 17 Jul 2007, Ingo Molnar wrote: > > i've got a new observation: changing CONFIG_HZ from 250 to 1000 makes > the problem go away. So it's somehow also related to jiffies. No, I suspect it's just related to timing: you need to hit that window when the LIST_FROZEN bit is set, and since it was so reliable for you before (and others didn't see it), your timing probably happened to hit it exactly. And changing HZ probably just changed some timeout or softirq getting called, and you didn't hit the bug any more. Linus