From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752013AbXCGPjJ (ORCPT ); Wed, 7 Mar 2007 10:39:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752007AbXCGPjJ (ORCPT ); Wed, 7 Mar 2007 10:39:09 -0500 Received: from smtp.osdl.org ([65.172.181.24]:40314 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752005AbXCGPjI (ORCPT ); Wed, 7 Mar 2007 10:39:08 -0500 Date: Wed, 7 Mar 2007 07:39:00 -0800 (PST) From: Linus Torvalds To: Benjamin Herrenschmidt cc: Greg KH , Linux Kernel Mailing List Subject: Re: Linux v2.6.21-rc3 In-Reply-To: <1173263132.9349.47.camel@localhost.localdomain> Message-ID: References: <1173263132.9349.47.camel@localhost.localdomain> 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 Wed, 7 Mar 2007, Benjamin Herrenschmidt wrote: > > On Tue, 2007-03-06 at 20:59 -0800, Linus Torvalds wrote: > > > Linus Torvalds (2): > > Revert "[PATCH] LOG2: Alter get_order() so that it can make use of ilog2() on a constant" > > Linux 2.6.21-rc3 > > Greg, I think we should revert that patch in 2.6.20.x stable serie too > as get_order is broken there as well, causing random kernel memory > corruption every now and then among others. Did you confirm that that was indeed the cause of the problem you saw? As far as I can tell, the bug (because it tested the wrong #define) would only affect the constant-size case, and only for something larger than a single page, and only for a non-power-of-two size. So it looked fairly hard to trigger, if only because all the obvious constants I saw seemed to already be powers-of-two.. So did you hunt it down to a particular cases where it triggers? Linus