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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 D377FC3279B for ; Mon, 2 Jul 2018 04:19:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 86E1625489 for ; Mon, 2 Jul 2018 04:19:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 86E1625489 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752211AbeGBEQo (ORCPT ); Mon, 2 Jul 2018 00:16:44 -0400 Received: from ozlabs.org ([203.11.71.1]:45701 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751443AbeGBEQn (ORCPT ); Mon, 2 Jul 2018 00:16:43 -0400 Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPSA id 41Jv8N2J94z9s3q; Mon, 2 Jul 2018 14:16:36 +1000 (AEST) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au From: Michael Ellerman To: Linus Torvalds , Larry Finger Cc: Matthew Wilcox , "Kirill A. Shutemov" , Vlastimil Babka , Christoph Lameter , Dave Hansen , Jerome Glisse , Lai Jiangshan , Martin Schwidefsky , Pekka Enberg , Randy Dunlap , Andrey Ryabinin , Andrew Morton , Benjamin Herrenschmidt , Paul Mackerras , ppc-dev , Linux Kernel Mailing List Subject: Re: [Update] Regression in 4.18 - 32-bit PowerPC crashes on boot - bisected to commit 1d40a5ea01d5 In-Reply-To: References: <99169786-61dd-b19c-ac81-84bcd0a67de4@lwfinger.net> Date: Mon, 02 Jul 2018 14:16:33 +1000 Message-ID: <87d0w6mfvi.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Linus Torvalds writes: > On Fri, Jun 29, 2018 at 1:42 PM Larry Finger wrote: >> >> I have more information regarding this BUG. Line 700 of page-flags.h is the >> macro PAGE_TYPE_OPS(Table, table). For further debugging, I manually expanded >> the macro, and found that the bug line is VM_BUG_ON_PAGE(!PageTable(page), page) >> in routine __ClearPageTable(), which is called from pgtable_page_dtor() in >> include/linux/mm.h. I also added a printk call to PageTable() that logs >> page->page_type. The routine was called twice. The first had page_type of >> 0xfffffbff, which would have been expected for a . The second call had >> 0xffffffff, which led to the BUG. > > So it looks to me like the tear-down of the page tables first found a > page that is indeed a page table, and cleared the page table bit > (well, it set it - the bits are reversed). ... > > That said, can some ppc person who knows the 32-bit ppc code and maybe > knows what that "interrupt: 700" means talk about that oddity in the > trace, please? I think everyone else answered your questions here, and it should be fixed now in your tree. Larry let me know if you're still seeing a crash with 4.18-rc3. cheers