From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.6 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2663DC433E6 for ; Mon, 31 Aug 2020 10:47:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 08E89206F0 for ; Mon, 31 Aug 2020 10:47:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726557AbgHaKr0 (ORCPT ); Mon, 31 Aug 2020 06:47:26 -0400 Received: from foss.arm.com ([217.140.110.172]:56396 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725964AbgHaKrY (ORCPT ); Mon, 31 Aug 2020 06:47:24 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id AA8E41FB; Mon, 31 Aug 2020 03:47:23 -0700 (PDT) Received: from [10.163.69.240] (unknown [10.163.69.240]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C7C3D3F71F; Mon, 31 Aug 2020 03:47:21 -0700 (PDT) Subject: Re: Warning on Kernel 5.9.0-rc1 on PowerBook G4 (ppc32), bisected to a5c3b9ffb0f4 To: Larry Finger , Michael Ellerman , Benjamin Herrenschmidt Cc: LKML , Christophe Leroy , Christophe Leroy References: From: Anshuman Khandual Message-ID: <6beb6fcd-6b9a-b25a-3e63-77bac571ab5d@arm.com> Date: Mon, 31 Aug 2020 16:16:49 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/29/2020 06:40 AM, Larry Finger wrote: > In kernel 5.9.0-rc1 on a PowerBook G4 (ppc32), several warnings of the following type are logged: > >  ------------[ cut here ]------------ >  WARNING: CPU: 0 PID: 1 at arch/powerpc/mm/pgtable.c:185 set_pte_at+0x20/0x100 All those warnings triggered at the same place i.e arch/powerpc/mm/pgtable.c:185 ? >  Modules linked in: >  CPU: 0 PID: 1 Comm: swapper Not tainted 5.9.0-rc2 #2 >  NIP:  c002add4 LR: c07dba40 CTR: 00000000 >  REGS: f1019d70 TRAP: 0700   Not tainted  (5.9.0-rc2) >  MSR:  00029032   CR: 22000888  XER: 00000000 > >    GPR00: c07dba40 f1019e28 eeca3220 eef7ace0 4e999000 eef7d664 f1019e50 00000000 >    GPR08: 007c2315 00000001 007c2315 f1019e48 22000888 00000000 c00054dc 00000000 >    GPR16: 00000000 00000000 2ef7d000 000007c2 fffffff0 eef7b000 000004e8 eef7d000 >    GPR24: eef7c5c0 00000000 007c2315 4e999000 c05ef548 eef7d664 c087cda8 007c2315 >  NIP [c002add4] set_pte_at+0x20/0x100 >  LR [c07dba40] debug_vm_pgtable+0x29c/0x654 >  Call Trace: >  [f1019e28] [c002b4ac] pte_fragment_alloc+0x24/0xe4 (unreliable) >  [f1019e48] [c07dba40] debug_vm_pgtable+0x29c/0x654 >  [f1019e98] [c0005160] do_one_initcall+0x70/0x158 >  [f1019ef8] [c07c352c] kernel_init_freeable+0x1f4/0x1f8 >  [f1019f28] [c00054f0] kernel_init+0x14/0xfc >  [f1019f38] [c001516c] ret_from_kernel_thread+0x14/0x1c >  Instruction dump: >  57ff053e 39610010 7c63fa14 4800308c 9421ffe0 7c0802a6 81250000 bfa10014 >  7cbd2b78 90010024 552907fe 83e60000 <0f090000> 3d20c089 83c91280 813e0018 >  ---[ end trace 4ef67686e5133716 ]--- > > Although the warnings do no harm, I suspect that they should be fixed in case some future modification turns the warning statements into BUGS. These warnings are from mm/debug_vm_pgtable.c test, wont be converted into BUGS. But nonetheless, need to be addressed though. > > The problem was bisected to commit a5c3b9ffb0f4 ("mm/debug_vm_pgtable: add tests validating advanced arch page table helpers") by Anshuman Khandual There are some known issues wrt DEBUG_VM_PGTABLE on certain ppc64 platforms. But I thought it worked all right on ppc32 platforms though. Adding Christophe Leroy here. Currently, there is a series under review that makes DEBUG_VM_PGTABLE work correctly on ppc64 platforms. Could you please give it a try and see if it fixes these warnings ? https://patchwork.kernel.org/project/linux-mm/list/?series=339387 - Anshuman