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=unavailable 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 D8FACC43444 for ; Wed, 19 Dec 2018 18:42:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A52D92070D for ; Wed, 19 Dec 2018 18:42:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="tpnaZUGb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729946AbeLSSm3 (ORCPT ); Wed, 19 Dec 2018 13:42:29 -0500 Received: from mail-it1-f193.google.com ([209.85.166.193]:53250 "EHLO mail-it1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728525AbeLSSm3 (ORCPT ); Wed, 19 Dec 2018 13:42:29 -0500 Received: by mail-it1-f193.google.com with SMTP id g85so11206940ita.3 for ; Wed, 19 Dec 2018 10:42:28 -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=HVTnhPYqJyasq4GmNoyFjBD0F8OLVw6YqkQSU93KBdY=; b=tpnaZUGbgoz462o647vKp2ar88rROAf2MVZiH4sMVVXE/fTbYoc+rOnp1vimrr8m4l GqNXWFFnAZH9ZTLqc6DYHrGkOa7clSx7ADZrYY2mdu846r7SX80ZO8oK2iKalkNxv4Fi btcUOJ7x87Veix6u1S0rz+fyVGwzxtKbxj4SiRITRYEf2oC8aMlns3RhhJXHG6xok0aP lHzRSLHjjMVdwSypY3sfGnFn7/6KbEiAQjcISrWPG7/7OIXAuwznluex1aU2Goz7ObBd wYe9S4jvdTvk7yQc39w0Cel8i7MhJYmGPjXhhKHnA1gHxzIa91HL6QkvTIqAKSkq7+C9 p8dA== 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=HVTnhPYqJyasq4GmNoyFjBD0F8OLVw6YqkQSU93KBdY=; b=ThbYG1GCSM5iAhCYLAGxLtLg5luS9vfm5cJzGFoIsbTt7QiGGpdLts6iB+aMsYmUsi PInzzzlwE7JuF9cMgpdfYu5Buwxbn/17XdS9MZS4JMmc3nrTUjbT4oHPFIIGjovWW8vb I7tF5Ut0SNClm//7tzRJqwTfje66Q0QX8mGybQVJ2+iXUbjx7wV9Ob1DpKc8yO2h4vBt LcE7C7eZzoZx7tfFB+RK1a4oFKgrvZLq7DT3n1fg6x3Gm60JPm8r8AhdSoeppb6WJUMj qZyL/sDsGgVfBMOAzIM31NXx+moeYOkXqSC81a/1NDlbt9MlC7EYrxePhwBZSezPo4nW PA9A== X-Gm-Message-State: AA+aEWaihJTTkL/vCVKAn+dqnhqH4aZtkY/0CYMMLjzusIVYs9BGdpIF KFdR0G42Eo+d5VPXwBbv9yd9Z1aKI71Mc+LUjo0CLw== X-Google-Smtp-Source: AFSGD/UkLvlYn0eBpl/X+v3zxqikD6cwHFRQKx65ub4SYezF8V3GWyw+MRd7ZD0ATXMdatVie/auLhxq2H9bPHZ8T/I= X-Received: by 2002:a02:8904:: with SMTP id o4mr20185222jaj.35.1545244948214; Wed, 19 Dec 2018 10:42:28 -0800 (PST) MIME-Version: 1.0 References: <000000000000e728ec057d5c9d90@google.com> In-Reply-To: From: Dmitry Vyukov Date: Wed, 19 Dec 2018 19:42:17 +0100 Message-ID: Subject: Re: INFO: rcu detected stall in sys_sendfile64 To: Tetsuo Handa Cc: syzbot , syzkaller-bugs , Ingo Molnar , Peter Zijlstra , James Morris , LKML , linux-security-module@vger.kernel.org, "Serge E. Hallyn" 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 Wed, Dec 19, 2018 at 11:13 AM Tetsuo Handa wrote: > > On 2018/12/19 18:27, syzbot wrote: > > HEAD commit: ddfbab46539f Merge tag 'scsi-fixes' of git://git.kernel.or.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=15b87fa3400000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=861a3573f4e78ba1 > > dashboard link: https://syzkaller.appspot.com/bug?extid=bcad772bbc241b4c6147 > > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13912ccd400000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=145781db400000 > > This is not a LSM problem, for the reproducer is calling > sched_setattr(SCHED_DEADLINE) with very large values. > > sched_setattr(0, {size=0, sched_policy=0x6 /* SCHED_??? */, sched_flags=0, sched_nice=0, sched_priority=0, sched_runtime=2251799813724439, sched_deadline=4611686018427453437, sched_period=0}, 0) = 0 > > I think that this problem is nothing but an insane sched_setattr() parameter. > > #syz invalid Note there was another one with sched_setattr, which turned out to be some serious problem in kernel (sched_setattr should not cause CPU stall for 3 minutes): INFO: rcu detected stall in do_idle https://syzkaller.appspot.com/bug?extid=385468161961cee80c31 https://groups.google.com/forum/#!msg/syzkaller-bugs/crrfvusGtwI/IoD_zus4BgAJ Maybe it another incarnation of the same bug, that one is still not fixed.