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=-13.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 D085DC282C4 for ; Tue, 22 Jan 2019 13:54:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A02FE20684 for ; Tue, 22 Jan 2019 13:54:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="aVCWuwo7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728644AbfAVNyk (ORCPT ); Tue, 22 Jan 2019 08:54:40 -0500 Received: from mail-it1-f196.google.com ([209.85.166.196]:37681 "EHLO mail-it1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728567AbfAVNyk (ORCPT ); Tue, 22 Jan 2019 08:54:40 -0500 Received: by mail-it1-f196.google.com with SMTP id b5so20106281iti.2 for ; Tue, 22 Jan 2019 05:54:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Vrt00XEE7hMYYWS1xWhRin/2a/MlUA+hgmbfZmskq54=; b=aVCWuwo7Clp4I+pwA2arLHCfiUT/pe0mMTF8n50T7goZtbdII5liIo8jGnMvTLuIdS Of/q0OyHMLQeEjJHPO40KdjvAUL1pHXivYdWbG/UjbAHlSWJDW33IDQbgeZLH8vEQkcW u10vFfMlkrukxsHOK69wftPOtYvn3Tt3HrY11UFrK/YE52KuhOXfZ2YUGETZEwlAYmLQ hznJaOetOSXedOMQBWYYPq8/JmRQ2xrUgtlrQqlPbIbsaWmigylrCEPFaiZSKXG0aeWq Aga//7XrkWjOfrpmzRJXXZ6I3KMbXThCkKy41e94FW4xpeq3fEwdnOwrP2U+JJ+wg3u0 KhWQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Vrt00XEE7hMYYWS1xWhRin/2a/MlUA+hgmbfZmskq54=; b=JvllbrEiy5Q4d/oPGGTN+0exJUkw8vaMbL3S9o3YvEOiqUzmmX50V7ixK84LLQg7xV khWGUr73YMzxhH9InSXw5Tvb5s7msOEhd4TOen7yDekkqjBhzJ1EHAw/XYR/bZCCcPA8 xkcnveSw8Nj2/s7ltZg2FWLzPBn11lMScCzqnl0Qp5nS6EqPf2mHSnf0EUaJa0DiyIha cJELlIjfpWtHKyl8zACc+dgxJMu1MclhGscVG+iywrbMR9H6hNDHDSbIYcpZkdqO9IRP N3Ju9bXMpW6qaEcPUwDOt39tCX+B3Nj6jmUTy6BbVxXgRRbz9jHSYt+seL7qB0x5wibP 8RAg== X-Gm-Message-State: AJcUukfhVrfnGNYJ2oHKzr5lx2E9/4vH7YRn5VU/l/nkRqhw8inkvZif YVe0aq3T8FC6YbeBxZhiOA+FnPxlT09/PZO859q3dw== X-Google-Smtp-Source: ALg8bN6M2+jLT9rXMFMYl0B6nASDNw3BP84b2+cgjyKYFpCgE6X3oicOiLJQvstcujV4l7DY9diQS1zg1kBSR9UAq1Q= X-Received: by 2002:a02:ac8c:: with SMTP id x12mr18479073jan.72.1548165279311; Tue, 22 Jan 2019 05:54:39 -0800 (PST) MIME-Version: 1.0 References: <000000000000f7a28e057653dc6e@google.com> <20180920141058.4ed467594761e073606eafe2@linux-foundation.org> <20180921162110.e22d09a9e281d194db3c8359@linux-foundation.org> <4b0a5f8c-2be2-db38-a70d-8d497cb67665@I-love.SAKURA.ne.jp> In-Reply-To: From: Dmitry Vyukov Date: Tue, 22 Jan 2019 14:54:28 +0100 Message-ID: Subject: Re: possible deadlock in __do_page_fault To: Tetsuo Handa 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 , Mel Gorman , syzkaller-bugs , =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= , Todd Kjos , Martijn Coenen , Greg Kroah-Hartman Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 22, 2019 at 2:52 PM Dmitry Vyukov wrote: > > On Tue, Jan 22, 2019 at 11:32 AM Tetsuo Handa > wrote: > > > > 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. > > Right. Let's do this. > > As with any kernel changes only you really know how to apply it, git > tree/base commit info is missing, so let's do guessing and > finger-crossing as usual: > > #syz fix: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git > master This of course should be: #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master