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=-6.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FSL_HELO_FAKE,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1, USER_IN_DEF_DKIM_WL autolearn=no 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 CE166C5DF60 for ; Thu, 7 Nov 2019 12:16:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 91240214D8 for ; Thu, 7 Nov 2019 12:16:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="tSxjozI0" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388415AbfKGMP7 (ORCPT ); Thu, 7 Nov 2019 07:15:59 -0500 Received: from mail-wr1-f46.google.com ([209.85.221.46]:44224 "EHLO mail-wr1-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726873AbfKGMP7 (ORCPT ); Thu, 7 Nov 2019 07:15:59 -0500 Received: by mail-wr1-f46.google.com with SMTP id f2so2716086wrs.11 for ; Thu, 07 Nov 2019 04:15:56 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=AhvFZA/8mu3kvXFq6TuCaJ1OmjGmDb6ipwRR9+wxEXI=; b=tSxjozI0LXsxPhnJbqXdF/zzwjjgM5fA2KPgToWN4mt83gWKz32OaWD3xznwGbAMqA IUwDFk6TfCIl0u9cg/6NEFMQnhInxYSCagxChSVX9/J92NSGs1W+ID57ynzueKlBZOL0 gDwRSm6z+go1F0/igdP0A9HrNovYYuQbPTHUA+gKSYV9vFhO2uI0pQD2Zp3MzR2G6/qa ZtkdhIy5YVkZ5U/QxpJNfkka+NqV+2ZtMoB0QK/UOfNdMbth/oLokLx9X0D+kiMQEYEx uzWdQ62vTGUG8Pf22fzXmAe3z2c2eS3FuaHELdZcnnGW+8I6XHJuBE/BEiXc/ofrDRFo avVQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=AhvFZA/8mu3kvXFq6TuCaJ1OmjGmDb6ipwRR9+wxEXI=; b=D2NForMz02at0ceBnYbDT9H6UpzPqedx6XP7BqmCwbskNZg80pEWSnFDSZkiatZ1ny mp2TUs6HjIoDHhDt3ZJ03wga/fAxUXb9xjNvLHgQHBT6DqchbVPP09qXxu5pB6j2E4et kseeJgkvd7N08v6nHV08aoD0aifXY+rNGVhv3VgMGznTCpDWaf4HzZgBJqS/5PeifVp8 82sLLub115nOm/LMLzDyxI6cX/1zDcZd3HDSqL+owy1Vc9Tq8hkAzei7Or/Gupun1f5/ fH8M7nEyWg1uZGW/U5e72kEAZEySrKNTG3siz9873eqr769IPQ63TJJR7bgHeP7qehEH Rg9A== X-Gm-Message-State: APjAAAXvyfphR1HoTq+Te10SETtIuH08/w+hyrdjpu64DiiqOt9YNZxO osKrmh0+rQn96NkyyzsEFPlKyQ== X-Google-Smtp-Source: APXvYqyEmwY5aHzXCIZs1wotO2/tgtomk2HcI006MSaOMZk7X3Kx3u0jFjkBqSkFHRu9pgkllEysgA== X-Received: by 2002:a5d:42c8:: with SMTP id t8mr2441298wrr.87.1573128955161; Thu, 07 Nov 2019 04:15:55 -0800 (PST) Received: from google.com ([2a00:79e0:d:110:d6cc:2030:37c1:9964]) by smtp.gmail.com with ESMTPSA id x8sm1644620wmi.10.2019.11.07.04.15.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 Nov 2019 04:15:54 -0800 (PST) Date: Thu, 7 Nov 2019 12:15:51 +0000 From: Quentin Perret To: Valentin Schneider Cc: kernel test robot , Peter Zijlstra , Aaron Lu , Phil Auld , Julien Desfossez , Nishanth Aravamudan , LKML , Linus Torvalds , lkp@01.org Subject: Re: [sched] 10e7071b2f: BUG:kernel_NULL_pointer_dereference,address Message-ID: <20191107121551.GB82729@google.com> References: <20191107090808.GW29418@shao2-debian> <20191107120922.GA82729@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191107120922.GA82729@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 07 Nov 2019 at 12:09:22 (+0000), Quentin Perret wrote: > sched_move_task() follows what Peter called the 'change' pattern, so I'm > thinking this is most likely the same issue. Dropping the lock causes an > unmitigated race between sched_move_task() and pick_next_task_dl(), so > hilarity ensues (set_next_task() being called twice for instance). Bah, scratch that. 10e7071b2 is clearly before the pick_next_task() rework, so that's not it :( Quentin