From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from digeo-nav01.digeo.com (digeo-nav01.digeo.com [192.168.1.233]) by packet.digeo.com (8.9.3+Sun/8.9.3) with SMTP id NAA14700 for ; Tue, 25 Feb 2003 13:31:04 -0800 (PST) Date: Tue, 25 Feb 2003 13:27:55 -0800 From: Andrew Morton Subject: Re: 2.5.62-mm3 - no X for me Message-Id: <20030225132755.241e85ac.akpm@digeo.com> In-Reply-To: <131360000.1046195828@[10.1.1.5]> References: <20030223230023.365782f3.akpm@digeo.com> <3E5A0F8D.4010202@aitel.hist.no> <20030224121601.2c998cc5.akpm@digeo.com> <20030225094526.GA18857@gemtek.lt> <20030225015537.4062825b.akpm@digeo.com> <131360000.1046195828@[10.1.1.5]> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Dave McCracken Cc: zilvinas@gemtek.lt, helgehaf@aitel.hist.no, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: Dave McCracken wrote: > > > --On Tuesday, February 25, 2003 01:55:37 -0800 Andrew Morton > wrote: > > > Ah, thank you. > > > > kernel BUG at mm/rmap.c:248! > > > > The fickle finger of fate points McCrackenwards. > > Yep. He tripped over my sanity check that pages not marked anon actually > have a real mapping pointer. Apparently X allocates a page that should be > marked anon but isn't. Wonder where that came from? > My main reason for adding the anon flag was to prove to myself that the > mapping pointer can be trusted. Apparently it can, generally, but it looks > like I haven't successfully tracked down all the places that should set it. > It looks like anon pages can come from random sources, so it might be an > impossible task to find them all. Yes, the debug check is important at this time. > I know you said you like the idea of having the flag, but I think the > cleanest fix would be to change the check from > > if (PageAnon(page)) > to > if (page->mapping && !PageSwapCache(page)) Well I'm not particularly overjoyed by the flag. What I liked was that we have a place where we can implement anonymous page counting, so we get another interesting number in /proc/meminfo. Minor point. > Or I could set the anon flag based on that test. I know page flags are > getting scarce, so I'm leaning toward removing the flag entirely. > > What would you recommend? Keep the flag for now, find the escaped page under X, remove the flag later? -- 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/ . Don't email: aart@kvack.org