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=-2.5 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 6C12EC06513 for ; Thu, 4 Jul 2019 10:17:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1D912218A0 for ; Thu, 4 Jul 2019 10:17:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Jy16tDD5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727562AbfGDKRO (ORCPT ); Thu, 4 Jul 2019 06:17:14 -0400 Received: from mail-pg1-f196.google.com ([209.85.215.196]:42842 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727529AbfGDKRO (ORCPT ); Thu, 4 Jul 2019 06:17:14 -0400 Received: by mail-pg1-f196.google.com with SMTP id t132so2696977pgb.9 for ; Thu, 04 Jul 2019 03:17:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:from:to:cc:references:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding:content-language; bh=s7SOe1F5ObWdkVUT2XPTzQRYpPi2RSZ9/8GPWAQIeeY=; b=Jy16tDD5PGT9KdFyc2APdwsHQ7zg8Fo6xUtjaNJ/MFlO8VhgnvqPJzheXf/rZLLfXY 12+lKTf13GJ/fAASVpSDypD8CeF11JxH4qBkaGJOeWsNaklQyfbOVnEKgwrqkn29ZGTH TQ0F8mKDlvCijteR1u0lAZEeJS3nsGPa9ZURmm+pyYA7bfD0Prkr7JX2SdpazsFT1fFc GU5Ft/vIxj68iLkE3rZy6nmQJ86ZOH13Dpc1lioGBLj+NlxxshS3uwiVVwzBv2YfHoq+ CrB0yTE9iVyDqITiUmkXMFn2uZgopiqUzNIDRdo3MuPJUF9IcdgWOrFBDScf/OBYVdzJ v4GQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:references:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=s7SOe1F5ObWdkVUT2XPTzQRYpPi2RSZ9/8GPWAQIeeY=; b=GCEyFJ8k3ZZOCqZy1eWLJVwntIh/jEsOWbckNAQhQ0ivCsqCWHsabqny0GN18QVtWP psasEd6lU4mWB8YSfd25YBtgOky//hYwyiDuMfUD/VDx33bSYDj+MK51pVPJkRked6UM TJ3+ulK1xPAPh2TSeBpdeC/E5oTHYrU9ioorz7kLSfv0Q8sa37qKxIGTHvn6vYt7rvvP mJ36daxhKCLZ9k/J7YBEPRu3kEQ6XVZWC7n3fOZyxmzkZ9wDLwmwd23v1VoFtdZ7nFJG WvCf2rROBJygztIOGRnHwrCRv3CEOxASRIM9zHhbildTESyohenCK8EdS/37ahzLpHmi Ab6Q== X-Gm-Message-State: APjAAAW08ShfzQ/BZiUPdXpp1UFBeQFV0lTgL5lQpm/LLg313YRSp2hz YB+E6CNWbVLjbhfNWHBjxCmCt/wWn18= X-Google-Smtp-Source: APXvYqzdbGxuj34YKYohv0ClOa+TqNsmSEDB4PXxcYLSKa2F4ASHI1/RUP8/nVE4MSgvgxL1tE8XNw== X-Received: by 2002:a17:90a:ad89:: with SMTP id s9mr18945231pjq.41.1562235433786; Thu, 04 Jul 2019 03:17:13 -0700 (PDT) Received: from [10.11.32.138] ([43.230.89.66]) by smtp.gmail.com with ESMTPSA id k8sm5868067pgm.14.2019.07.04.03.17.12 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Thu, 04 Jul 2019 03:17:13 -0700 (PDT) Subject: Re: schdule bug in 4.4.38-rt49 From: "xiaoqiang.zhao" To: Sebastian Andrzej Siewior Cc: linux-rt-users@vger.kernel.org References: <55c68f08-4160-4bee-fdc5-9fc1ea86cf57@gmail.com> <20190703114256.3b52kbrududxq7vz@linutronix.de> <987eec05-14d0-29a5-723c-7bfbc0a5465b@gmail.com> Message-ID: <3d020904-95c2-9cb1-1560-c1a2c931ba83@gmail.com> Date: Thu, 4 Jul 2019 18:17:09 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <987eec05-14d0-29a5-723c-7bfbc0a5465b@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-rt-users-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org Resend as plain-text to linux-rt-users list. 在 2019/7/4 下午1:50, xiaoqiang.zhao 写道: 在 2019/7/3 下午7:42, Sebastian Andrzej Siewior 写道: > On 2019-06-26 15:35:04 [+0800], xiaoqiang.zhao wrote: >> Hi, guys: > Hi, > Thanks for your reply ;-) >> 2) -> __schedule_bug ( leads to kernel pagefault exception, OOPS!!) >> >> Before schedule, we have call preempt_disable twice, this will >> definitely >> bump preempt_count to 2 and > > something probably disabled preemption before that I feel this is not make sense.  In my opinion, the preempt_count must be zero before we call 'schedule()', otherwise, in_atomic_preempt_off will return true and trigger the __schedule_bug. If we have already disable_preempt, we may in atomic context and we should not call schedule, right ? >> in_atomic_preempt_off will fail. >> >> I did not figure out:   WHY we call schedule inside >> rt_spin_lock_slowlock >> and under what condition this call is correct ? > if the lock is acquired you schedule out and wait und it is available > again. got this. >