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=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 ABF71C04E53 for ; Wed, 15 May 2019 14:58:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8162320881 for ; Wed, 15 May 2019 14:58:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726859AbfEOO6x (ORCPT ); Wed, 15 May 2019 10:58:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54858 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725939AbfEOO6w (ORCPT ); Wed, 15 May 2019 10:58:52 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9483430BB36D; Wed, 15 May 2019 14:58:41 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.159]) by smtp.corp.redhat.com (Postfix) with SMTP id 8F97719C7C; Wed, 15 May 2019 14:58:35 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Wed, 15 May 2019 16:58:38 +0200 (CEST) Date: Wed, 15 May 2019 16:58:32 +0200 From: Oleg Nesterov To: Sultan Alsawaf Cc: Christian Brauner , Daniel Colascione , Suren Baghdasaryan , Steven Rostedt , Tim Murray , Michal Hocko , Greg Kroah-Hartman , Arve =?iso-8859-1?B?SGr4bm5lduVn?= , Todd Kjos , Martijn Coenen , Ingo Molnar , Peter Zijlstra , LKML , "open list:ANDROID DRIVERS" , linux-mm , kernel-team , Andy Lutomirski , "Serge E. Hallyn" , Kees Cook , Joel Fernandes Subject: Re: [RFC] simple_lmk: Introduce Simple Low Memory Killer for Android Message-ID: <20190515145831.GD18892@redhat.com> References: <20190319231020.tdcttojlbmx57gke@brauner.io> <20190320015249.GC129907@google.com> <20190507021622.GA27300@sultan-box.localdomain> <20190507153154.GA5750@redhat.com> <20190507163520.GA1131@sultan-box.localdomain> <20190509155646.GB24526@redhat.com> <20190509183353.GA13018@sultan-box.localdomain> <20190510151024.GA21421@redhat.com> <20190513164555.GA30128@sultan-box.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190513164555.GA30128@sultan-box.localdomain> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Wed, 15 May 2019 14:58:52 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/13, Sultan Alsawaf wrote: > > On Fri, May 10, 2019 at 05:10:25PM +0200, Oleg Nesterov wrote: > > I am starting to think I am ;) > > > > If you have task1 != task2 this code > > > > task_lock(task1); > > task_lock(task2); > > > > should trigger print_deadlock_bug(), task1->alloc_lock and task2->alloc_lock are > > the "same" lock from lockdep pov, held_lock's will have the same hlock_class(). > > Okay, I've stubbed out debug_locks_off(), and lockdep is now complaining about a > bunch of false positives so it is _really_ enabled this time. Could you explain in detail what exactly did you do and what do you see in dmesg? Just in case, lockdep complains only once, print_circular_bug() does debug_locks_off() so it it has already reported another false positive __lock_acquire() will simply return after that. Oleg.