Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Tue, 14 May 2019 12:44:53 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Sultan Alsawaf <sultan@kerneltoast.com>
Cc:     Oleg Nesterov <oleg@redhat.com>,
        Christian Brauner <christian@brauner.io>,
        Daniel Colascione <dancol@google.com>,
        Suren Baghdasaryan <surenb@google.com>,
        Tim Murray <timmurray@google.com>,
        Michal Hocko <mhocko@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Arve =?UTF-8?B?SGrDuG5uZXbDpWc=?= <arve@android.com>,
        Todd Kjos <tkjos@android.com>,
        Martijn Coenen <maco@android.com>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        "open list:ANDROID DRIVERS" <devel@driverdev.osuosl.org>,
        linux-mm <linux-mm@kvack.org>,
        kernel-team <kernel-team@android.com>,
        Andy Lutomirski <luto@amacapital.net>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        Kees Cook <keescook@chromium.org>,
        Joel Fernandes <joel@joelfernandes.org>
Subject: Re: [RFC] simple_lmk: Introduce Simple Low Memory Killer for
 Android
Message-ID: <20190514124453.6fb1095d@oasis.local.home>
In-Reply-To: <20190513164555.GA30128@sultan-box.localdomain>
References: <20190319221415.baov7x6zoz7hvsno@brauner.io>
        <CAKOZuessqcjrZ4rfGLgrnOhrLnsVYiVJzOj4Aa=o3ZuZ013d0g@mail.gmail.com>
        <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-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, 13 May 2019 09:45:55 -0700
Sultan Alsawaf <sultan@kerneltoast.com> 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().  

OK, this has gotten my attention.

This thread is quite long, do you have a git repo I can look at, and
also where is the first task_lock() taken before the
find_lock_task_mm()?

-- Steve