Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751355AbeAPQlP (ORCPT + 1 other); Tue, 16 Jan 2018 11:41:15 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:39951 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750750AbeAPQlN (ORCPT ); Tue, 16 Jan 2018 11:41:13 -0500 Subject: Re: [REGRESSION][v4.14.y][v4.15] x86/intel_rdt/cqm: Improve limbo list processing To: "Shankar, Ravi V" , Thomas Gleixner Cc: "vikas.shivappa@linux.intel.com" , "stable@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "Luck, Tony" , "Yu, Fenghua" , "peterz@infradead.org" , "eranian@google.com" , "ak@linux.intel.com" , "davidcc@google.com" , "mingo@redhat.com" , "hpa@zytor.com" , "x86@kernel.org" , "1733662@bugs.launchpad.net" <1733662@bugs.launchpad.net>, "Roderick W. Smith" References: <84b8d891-6217-f56d-8ec0-313f7eb317c9@canonical.com> <159B72D0-06FE-4925-A11A-1F8A7741BF70@intel.com> From: Joseph Salisbury Message-ID: Date: Tue, 16 Jan 2018 11:40:26 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <159B72D0-06FE-4925-A11A-1F8A7741BF70@intel.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On 01/16/2018 08:32 AM, Shankar, Ravi V wrote: > Vikas on vacation until end of the month. Fenghua will look into this > issue. > > On Jan 16, 2018, at 5:09 AM, Thomas Gleixner > wrote: > >> >> Vikas, Fenghua can you please look at that ASAP? >> >> On Sun, 14 Jan 2018, Thomas Gleixner wrote: >> >>> On Fri, 12 Jan 2018, Joseph Salisbury wrote: >>> >>>> Hi Vikas, >>>> >>>> A kernel bug report was opened against Ubuntu [0].? After a kernel >>>> bisect, it was found that reverting the following commit resolved >>>> this bug: >>>> >>>> commit 24247aeeabe99eab13b798ccccc2dec066dd6f07 >>>> Author: Vikas Shivappa >>> > >>>> Date:?? Tue Aug 15 18:00:43 2017 -0700 >>>> >>>> ??? x86/intel_rdt/cqm: Improve limbo list processing >>>> >>>> >>>> The regression was introduced as of v4.14-r1 and still exists with >>>> current mainline.? The trace with v4.15-rc7 is in comment #44[1]. >>>> >>>> I was hoping to get your feedback, since you are the patch author.? Do >>>> you think gathering any additional data will help diagnose this issue, >>>> or would it be best to submit a revert request? >>> >>> That stinks like a use after free. Can you run with KASAN enabled? >>> >>> Thanks, >>> >>> ? ?tglx Here is some data wiht KASAN enabled: https://bugs.launchpad.net/ubuntu/+source/linux-hwe/+bug/1733662/comments/51 Are there any specific logs you would like to see, or specific actions executed? Thanks, Joe