From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755994Ab3KGW5M (ORCPT ); Thu, 7 Nov 2013 17:57:12 -0500 Received: from smtp.codeaurora.org ([198.145.11.231]:51484 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753584Ab3KGW5G (ORCPT ); Thu, 7 Nov 2013 17:57:06 -0500 Message-ID: <527C1AC0.2040206@codeaurora.org> Date: Thu, 07 Nov 2013 14:57:04 -0800 From: Olav Haugan Organization: Qualcomm Innovation Center, Inc. User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Greg KH CC: ngupta@vflare.org, sjenning@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, minchan@kernel.org, linux-arm-msm@vger.kernel.org Subject: Re: [PATCH] staging: zsmalloc: Ensure handle is never 0 on success References: <1383699252-8898-1-git-send-email-ohaugan@codeaurora.org> <20131106015645.GA28769@kroah.com> <527AD802.6020902@codeaurora.org> <20131107030640.GD8482@kroah.com> In-Reply-To: <20131107030640.GD8482@kroah.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/6/2013 7:06 PM, Greg KH wrote: > On Wed, Nov 06, 2013 at 04:00:02PM -0800, Olav Haugan wrote: >> On 11/5/2013 5:56 PM, Greg KH wrote: >>> On Tue, Nov 05, 2013 at 04:54:12PM -0800, Olav Haugan wrote: >>>> zsmalloc encodes a handle using the page pfn and an object >>>> index. On some hardware platforms the pfn could be 0 and this >>>> causes the encoded handle to be 0 which is interpreted as an >>>> allocation failure. >>> >>> What platforms specifically have this issue? >> >> Currently some of Qualcomm SoC's have physical memory that starts at >> address 0x0 which causes this problem. > > Then say this, and list the exact SoC's that can have this problem so > people know how to evaluate the bugfix and see if it is relevant for > their systems. > >> I believe this could be a problem >> on any platforms if memory is configured to be starting at physical >> address 0x0 for these platforms. > > Have you seen this be a problem? So it's just a theoretical issue at > this point in time? Yes, I can consistently reproduce it. It is not just theoretical. Thanks, Olav Haugan -- The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation