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=-8.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,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 ED760C388F7 for ; Fri, 13 Nov 2020 16:13:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AEAC62076E for ; Fri, 13 Nov 2020 16:13:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726997AbgKMQNm (ORCPT ); Fri, 13 Nov 2020 11:13:42 -0500 Received: from smtprelay0220.hostedemail.com ([216.40.44.220]:52788 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726437AbgKMQNm (ORCPT ); Fri, 13 Nov 2020 11:13:42 -0500 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay03.hostedemail.com (Postfix) with ESMTP id 0D394837F24A; Fri, 13 Nov 2020 16:13:41 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: owl98_140d4ca27310 X-Filterd-Recvd-Size: 2867 Received: from XPS-9350.home (unknown [47.151.133.149]) (Authenticated sender: joe@perches.com) by omf15.hostedemail.com (Postfix) with ESMTPA; Fri, 13 Nov 2020 16:13:37 +0000 (UTC) Message-ID: <97b1b575659bc87a07a308765769451d9eee4aef.camel@perches.com> Subject: Re: [mm] b6efe2fcc4: BUG:kernel_NULL_pointer_dereference,address From: Joe Perches To: kernel test robot Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, 0day robot , lkp@lists.01.org, ltp@lists.linux.it Date: Fri, 13 Nov 2020 08:13:36 -0800 In-Reply-To: <20201113121025.GA7578@xsang-OptiPlex-9020> References: <20201113121025.GA7578@xsang-OptiPlex-9020> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.38.1-1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2020-11-13 at 20:10 +0800, kernel test robot wrote: > Greeting, > > FYI, we noticed the following commit (built with gcc-9): > > commit: b6efe2fcc4e11010710ef5cd8e2bcbeb221a06c6 ("mm: slub: Convert sysfs sprintf family to sysfs_emit/sysfs_emit_at") > url: https://github.com/0day-ci/linux/commits/Joe-Perches/mm-Convert-sysfs-sprintf-family-to-sysfs_emit/20201102-041456 [] > on test machine: 8 threads Intel(R) Core(TM) i7-7700 CPU @ 3.60GHz with 32G memory > > caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): > > If you fix the issue, kindly add following tag > Reported-by: kernel test robot > > [ 41.689368] BUG: kernel NULL pointer dereference, address: 0000000000000010 > [ 41.696354] #PF: supervisor read access in kernel mode > [ 41.701508] #PF: error_code(0x0000) - not-present page > [ 41.706661] PGD 0 P4D 0 > [ 41.709205] Oops: 0000 [#1] SMP PTI > [ 41.712702] CPU: 3 PID: 4619 Comm: read_all Tainted: G I 5.10.0-rc1-00005-gb6efe2fcc4e1 #1 > [ 41.722296] Hardware name: Dell Inc. OptiPlex 7050/062KRH, BIOS 1.2.0 12/22/2016 > [ 41.729714] RIP: 0010:slabs_cpu_partial_show+0x95/0xe0 Right, thanks. I mistakenly dropped a test for page below: @@ -5156,44 +5156,45 @@ static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf) page = slub_percpu_partial(per_cpu_ptr(s->cpu_slab, cpu)); - if (page && len < PAGE_SIZE - 20) - len += sprintf(buf + len, " C%d=%d(%d)", cpu, - page->pobjects, page->pages); + len += sysfs_emit_at(buf, len, " C%d=%d(%d)", + cpu, page->pobjects, page->pages); } I'll correct it and resubmit.