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=-1.0 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 B73B7C282C3 for ; Tue, 22 Jan 2019 10:32:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 90CE72084A for ; Tue, 22 Jan 2019 10:32:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727676AbfAVKcj (ORCPT ); Tue, 22 Jan 2019 05:32:39 -0500 Received: from www262.sakura.ne.jp ([202.181.97.72]:41135 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726284AbfAVKci (ORCPT ); Tue, 22 Jan 2019 05:32:38 -0500 Received: from fsav405.sakura.ne.jp (fsav405.sakura.ne.jp [133.242.250.104]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id x0MAWajS024510; Tue, 22 Jan 2019 19:32:36 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav405.sakura.ne.jp (F-Secure/fsigk_smtp/530/fsav405.sakura.ne.jp); Tue, 22 Jan 2019 19:32:36 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/530/fsav405.sakura.ne.jp) Received: from [192.168.1.8] (softbank126126163036.bbtec.net [126.126.163.36]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id x0MAWZBB024496 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NO); Tue, 22 Jan 2019 19:32:35 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: possible deadlock in __do_page_fault To: Dmitry Vyukov Cc: Andrew Morton , Joel Fernandes , Todd Kjos , Joel Fernandes , syzbot+a76129f18c89f3e2ddd4@syzkaller.appspotmail.com, Andi Kleen , Johannes Weiner , Jan Kara , Souptick Joarder , LKML , Linux-MM , Matthew Wilcox , Mel Gorman , syzkaller-bugs , =?UTF-8?Q?Arve_Hj=c3=b8nnev=c3=a5g?= , Todd Kjos , Martijn Coenen , Greg Kroah-Hartman References: <000000000000f7a28e057653dc6e@google.com> <20180920141058.4ed467594761e073606eafe2@linux-foundation.org> <20180921162110.e22d09a9e281d194db3c8359@linux-foundation.org> <4b0a5f8c-2be2-db38-a70d-8d497cb67665@I-love.SAKURA.ne.jp> From: Tetsuo Handa Message-ID: Date: Tue, 22 Jan 2019 19:32:34 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/01/22 19:12, Dmitry Vyukov wrote: > On Tue, Jan 22, 2019 at 11:02 AM Tetsuo Handa > wrote: >> >> On 2018/09/22 8:21, Andrew Morton wrote: >>> On Thu, 20 Sep 2018 19:33:15 -0400 Joel Fernandes wrote: >>> >>>> On Thu, Sep 20, 2018 at 5:12 PM Todd Kjos wrote: >>>>> >>>>> +Joel Fernandes >>>>> >>>>> On Thu, Sep 20, 2018 at 2:11 PM Andrew Morton wrote: >>>>>> >>>>>> >>>>>> Thanks. Let's cc the ashmem folks. >>>>>> >>>> >>>> This should be fixed by https://patchwork.kernel.org/patch/10572477/ >>>> >>>> It has Neil Brown's Reviewed-by but looks like didn't yet appear in >>>> anyone's tree, could Greg take this patch? >>> >>> All is well. That went into mainline yesterday, with a cc:stable. >>> >> >> This problem was not fixed at all. > > There are at least 2 other open deadlocks involving ashmem: Yes, they involve ashmem_shrink_scan() => {shmem|vfs}_fallocate() sequence. This approach tries to eliminate this sequence. > > https://syzkaller.appspot.com/bug?extid=148c2885d71194f18d28 > https://syzkaller.appspot.com/bug?extid=4b8b031b89e6b96c4b2e > > Does this fix any of these too? I need checks from ashmem folks whether this approach is possible/correct. But you can ask syzbot to test this patch before ashmem folks respond.