Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161584AbXBOWju (ORCPT ); Thu, 15 Feb 2007 17:39:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161579AbXBOWju (ORCPT ); Thu, 15 Feb 2007 17:39:50 -0500 Received: from netops-testserver-3-out.sgi.com ([192.48.171.28]:45325 "EHLO netops-testserver-3.corp.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1161580AbXBOWjt (ORCPT ); Thu, 15 Feb 2007 17:39:49 -0500 Date: Thu, 15 Feb 2007 14:39:48 -0800 (PST) From: Christoph Lameter To: James Morris cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: 2.6.20-mm1 [kernel BUG at mm/swap.c:442] In-Reply-To: <20070215135157.18085ae3.akpm@linux-foundation.org> Message-ID: References: <20070215051408.a7fb7d81.akpm@linux-foundation.org> <20070215135157.18085ae3.akpm@linux-foundation.org> 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 Content-Length: 1486 Lines: 38 On Thu, 15 Feb 2007, Andrew Morton wrote: > I don't immediately see why that code isn't racy: the page can remain > in the pagevec for arbitrary amounts of time and someone can come along > and mlock it again. But given the ease with which you're hitting this, > it may not be a race. As long as the page is on the pagevec it should be off the LRU. Marking a page PageMlocked requires the page to be on the LRU. So a page cannot be marked PageMlocked as long as it is on the regular pagevecs. Somehow a page off the LRU was marked PageMlocked. Or a new anonymous page was allocated and marked PageMlocked and then some later processing put it onto the LRU? Maybe try_to_set_mlocked does work some havoc here. Could you see if this patch fixes it? This just disabled an optimization to set PageMlocked early. Index: linux-2.6.20-mm1/mm/memory.c =================================================================== --- linux-2.6.20-mm1.orig/mm/memory.c 2007-02-15 14:35:41.000000000 -0800 +++ linux-2.6.20-mm1/mm/memory.c 2007-02-15 14:35:54.000000000 -0800 @@ -930,6 +930,8 @@ static void try_to_set_mlocked(struct pa struct zone *zone; unsigned long flags; + return; + if (!PageLRU(page) || PageMlocked(page)) return; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/