From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f49.google.com (mail-pa0-f49.google.com [209.85.220.49]) by kanga.kvack.org (Postfix) with ESMTP id 384B4900014 for ; Tue, 11 Nov 2014 16:05:00 -0500 (EST) Received: by mail-pa0-f49.google.com with SMTP id lj1so11290724pab.22 for ; Tue, 11 Nov 2014 13:05:00 -0800 (PST) Received: from cdptpa-oedge-vip.email.rr.com (cdptpa-outbound-snat.email.rr.com. [107.14.166.226]) by mx.google.com with ESMTP id au4si20902864pbd.174.2014.11.11.13.04.58 for ; Tue, 11 Nov 2014 13:04:58 -0800 (PST) Date: Tue, 11 Nov 2014 16:04:48 -0500 From: Steven Rostedt Subject: Re: [BUG] mm/page-writeback.c: divide by zero in pos_ratio_polynom not fixed Message-ID: <20141111160448.61354836@gandalf.local.home> In-Reply-To: <20141111201539.GA12333@quack.suse.cz> References: <20141101082325.7be0463f@gandalf.local.home> <20141111201539.GA12333@quack.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Jan Kara Cc: Rik van Riel , LKML , Michal Hocko , linux-mm@kvack.org, Mel Gorman , Andrew Morton On Tue, 11 Nov 2014 21:15:39 +0100 Jan Kara wrote: > So I was looking into this but I have to say I don't understand where is > the problem. The registers clearly show that x_intercept - bdi_setpoint + 1 > == 0 (in 32-bit arithmetics). Given: > x_intercept = bdi_setpoint + span > > We have that span + 1 == 0 and that means that: > ((thresh - bdi_thresh + 8 * write_bw) * (u64)x >> 16) == -1 (again in > 32-bit arithmetics). But I don't see how that can realistically happen... > > Is this reproducible at all? > Unfortunately not. It only happened once, and I haven't been able to reproduce it again. -- Steve -- 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: email@kvack.org