Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756290AbXL2EwT (ORCPT ); Fri, 28 Dec 2007 23:52:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754762AbXL2EwM (ORCPT ); Fri, 28 Dec 2007 23:52:12 -0500 Received: from terminus.zytor.com ([198.137.202.10]:57033 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754632AbXL2EwL (ORCPT ); Fri, 28 Dec 2007 23:52:11 -0500 Message-ID: <4775D276.7040301@zytor.com> Date: Fri, 28 Dec 2007 20:52:06 -0800 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Jonathan Lim CC: linux-kernel@vger.kernel.org, jlan@sgi.com Subject: Re: [PATCH] Provide u64 version of jiffies_to_usecs() in kernel/tsacct.c References: <200712282126.lBSLQ76K042714@sabah.engr.sgi.com> In-Reply-To: <200712282126.lBSLQ76K042714@sabah.engr.sgi.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 601 Lines: 14 Jonathan Lim wrote: > It's possible that the values used in and returned from jiffies_to_usecs() are > incorrect because of truncation when variables of type u64 are involved. So a > function specific to that type is used instead. Much worse than that. There are internal overflows in the conversions. See the patch I recently submitted to -mm. -hpa -- 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/