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_PASS,USER_AGENT_MUTT 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 8B77FC04EB8 for ; Wed, 12 Dec 2018 05:04:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 51AC720811 for ; Wed, 12 Dec 2018 05:04:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="QTjG9tpw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 51AC720811 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726417AbeLLFEi (ORCPT ); Wed, 12 Dec 2018 00:04:38 -0500 Received: from mail-pf1-f196.google.com ([209.85.210.196]:46970 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726237AbeLLFEh (ORCPT ); Wed, 12 Dec 2018 00:04:37 -0500 Received: by mail-pf1-f196.google.com with SMTP id c73so8253752pfe.13; Tue, 11 Dec 2018 21:04:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=AZkcxCL3eo/u3eWNKY17NVrQBiummIjTchhD+nXK+uQ=; b=QTjG9tpwSzrgH2Y7NBZYTBjiOeMjqxsB+qr3w26kCeprv9/aNMOQasF/dwM2eexyFo 7Z6Un5MvsOiACy8BkaG52FzaL1f7I1Vc3zPHzQLgzF8OBDWIrAzIbODZcw1zK++5Xf7u UHe7WwfEoSpZyEhW2Lx0s4A+utJ2lqh/CvQVxHq/i/R3vatOEjiUuVGviP7/aOxSbpSW HwfsHMC4x6WQb4LjidRDzT1uxdp8ZsoEntEUwoPN1SgBX0gb2w6XqZ49jxdChJVVGFVi I/tYWbsQxK10OmUZyQM0T2I4RTX/QL0bOIDcrBPMzq6LNyqrPisyxRDUTdwlibnsUOKi 35AA== 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=AZkcxCL3eo/u3eWNKY17NVrQBiummIjTchhD+nXK+uQ=; b=A5uer70s8YxPNvAkMKQ5dIPdug3Qb/+fAsKGx8WVmfpHFKjWhlsmZPmRdaqpP9tG+L KIpZThlXq8mOC/x+wV+uGcjlC1q+ds0zNcmwSulwnRRYUN/dsMzIIssxsfzPI3ZUaA+U qA0mwyU41HubrQrDngEKyk4pSoD0qER7cp61cHhcWvyGSyDi5TwEh2ey+CamzS2jpKue S6V7gAb9nDiWb9NS+LZZSRY80aLs2Y5vFFCx57uY4+KmN4pHhqcvIbGWSxrRTO9TvKxR /s56mMocK9T6UqUuyRXKgTtkZoXjA6zpt2f2XMaUoBVY0ZqPDHakiwQ1MxZdgmbzrrCc owCQ== X-Gm-Message-State: AA+aEWb9xd8j/RN1+bSqRs/UF43TNdyDpIuaF5WvHr8tgF4ThnsISxQE fr9b2UYXwFrSDrJy2gEiFKQ= X-Google-Smtp-Source: AFSGD/V3byIKQY6BMKaHpLtydiPE5qF8OQuVwVp2N/J1+titrzHDUUYw4QSb/pmELhLhxh1wkjzXUQ== X-Received: by 2002:aa7:824f:: with SMTP id e15mr17890621pfn.192.1544591076557; Tue, 11 Dec 2018 21:04:36 -0800 (PST) Received: from localhost ([211.246.69.141]) by smtp.gmail.com with ESMTPSA id z191sm18529510pgd.74.2018.12.11.21.04.34 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 11 Dec 2018 21:04:35 -0800 (PST) Date: Wed, 12 Dec 2018 14:04:32 +0900 From: Sergey Senozhatsky To: Dmitry Safonov Cc: Jiri Slaby , kernel test robot , lkp@01.org, Greg Kroah-Hartman , Mikulas Patocka , LKML , linux-serial@vger.kernel.org, Sergey Senozhatsky , Petr Mladek , Steven Rostedt , Peter Zijlstra , Waiman Long , Sergey Senozhatsky Subject: Re: [LKP] [tty] c96cf923a9: WARNING:possible_circular_locking_dependency_detected Message-ID: <20181212050432.GE431@jagdpanzerIV> References: <20181211091154.GL23332@shao2-debian> <2780774e-b397-dcc2-6950-cccb527d5014@arista.com> <20181212034252.GD431@jagdpanzerIV> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181212034252.GD431@jagdpanzerIV> User-Agent: Mutt/1.11.1 (2018-12-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (12/12/18 12:42), Sergey Senozhatsky wrote: [..] > > >> [ 87.255156] CPU0 CPU1 > > >> [ 87.255813] ---- ---- > > >> [ 87.256460] lock(&port_lock_key); > > >> [ 87.256973] lock(console_owner); > > >> [ 87.257829] lock(&port_lock_key); > > >> [ 87.258680] lock(&obj_hash[i].lock); > > So it's like > > CPU0 CPU1 > > uart_shutdown() db->lock > uart_port->lock debug_print_object() > free_page() printk > debug_check_no_obj_freed uart_port->lock > db->lock > > > In this particular case we probably can just move free_page() > out of uart_port lock scope. Note that free_page()->MM can printk() > on its own. > [..] > > [1] https://lore.kernel.org/lkml/1542653726-5655-8-git-send-email-longman@redhat.com/T/#u That said, I'd first try Waiman's patch. The one I suggested is more of a defense move - there are too many things happening under uart_port->lock. This is not the first time we see lockdep complaining about the way uart and the rest of the kernel interact. -ss