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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 28F7BC4338F for ; Mon, 23 Aug 2021 07:56:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0CD2B6115A for ; Mon, 23 Aug 2021 07:56:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235357AbhHWH4x (ORCPT ); Mon, 23 Aug 2021 03:56:53 -0400 Received: from mail-vs1-f41.google.com ([209.85.217.41]:40755 "EHLO mail-vs1-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235263AbhHWH4v (ORCPT ); Mon, 23 Aug 2021 03:56:51 -0400 Received: by mail-vs1-f41.google.com with SMTP id h29so8184113vsr.7; Mon, 23 Aug 2021 00:56:09 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=bO20WydNuUjicbzTyFZXQBF0DVpWSwKIJdDjl+VnxdI=; b=FlqhUFLsgf820Fnm207VUxAruP6Em7I3U7iCjyNkX30DAXODEZslEYO17X9auGNjdC Owoy9ZwEsHTO5rttHTyOxiVtxsBgGo6psXXpruKWe6nwWSY9tVW9FngJR3n2RQ9sScnW BX3TMoHG6EY3ulm7cOCAS4I4h+AHM3ANZe2cQUDTRO9p8jsD6EqfICM6UQ5K7wwnE0c/ N+DRlR041Drx7DRzTPkggY3KHH1bACK5wTDyPHPDCB+sV/uTLbRo6sp0cJcnm+RO08RU D9XY25TOhTIo66GuPB176tyLayWj5tdUnFO8E0d6epENTUPg6pIsIL9i11pGdfb4JJhl HIqQ== X-Gm-Message-State: AOAM5310y4BUrX/1GL8G+gtSmKCz+eQQeI5piT288VDOPRSIC1TQkXRX fE4YjnNfLVS1RUSsb+IZAY9SF4NdOl/OHboWbw8= X-Google-Smtp-Source: ABdhPJxMhnJoTSMt1e3XrfAQGUikNOXfRuWG7TZ644Gun+YviYlr+fG1nVKaZQa7BFgcKGc/DC0y/v+xN1ESjGAyAXg= X-Received: by 2002:a05:6102:3e92:: with SMTP id m18mr22891652vsv.53.1629705368522; Mon, 23 Aug 2021 00:56:08 -0700 (PDT) MIME-Version: 1.0 References: <20210812084348.6521-1-david@redhat.com> <87o8a2d0wf.fsf@disp2133> <60db2e61-6b00-44fa-b718-e4361fcc238c@www.fastmail.com> <87lf56bllc.fsf@disp2133> <87eeay8pqx.fsf@disp2133> <5b0d7c1e73ca43ef9ce6665fec6c4d7e@AcuMS.aculab.com> <87h7ft2j68.fsf@disp2133> <87k0kkxbjn.fsf_-_@disp2133> <0c2af732e4e9f74c9d20b09fc4b6cbae40351085.camel@kernel.org> <639d90212662cf5cdf80c71bbfec95907c70114a.camel@kernel.org> In-Reply-To: From: Geert Uytterhoeven Date: Mon, 23 Aug 2021 09:55:57 +0200 Message-ID: Subject: Re: Removing Mandatory Locks To: David Laight Cc: Linus Torvalds , Jeff Layton , "Eric W. Biederman" , Matthew Wilcox , Andy Lutomirski , David Hildenbrand , Linux Kernel Mailing List , Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Al Viro , Alexey Dobriyan , Steven Rostedt , "Peter Zijlstra (Intel)" , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Petr Mladek , Sergey Senozhatsky , Andy Shevchenko , Rasmus Villemoes , Kees Cook , Greg Ungerer , Mike Rapoport , Vlastimil Babka , Vincenzo Frascino , Chinwen Chang , Michel Lespinasse , Catalin Marinas , Huang Ying , Jann Horn , Feng Tang , Kevin Brodsky , Michael Ellerman , Shawn Anastasio , Steven Price , Nicholas Piggin , Christian Brauner , Jens Axboe , Gabriel Krisman Bertazi , Peter Xu , Suren Baghdasaryan , Shakeel Butt , Marco Elver , Daniel Jordan , Nicolas Viennot , Thomas Cedeno , Collin Fijalkovich , Michal Hocko , Miklos Szeredi , Chengguang Xu , =?UTF-8?Q?Christian_K=C3=B6nig?= , "linux-unionfs@vger.kernel.org" , Linux API , "the arch/x86 maintainers" , "" , Linux-MM , Florian Weimer , Michael Kerrisk Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 20, 2021 at 10:30 AM David Laight wrote: > From: Linus Torvalds > > Sent: 19 August 2021 23:33 > > > > On Thu, Aug 19, 2021 at 2:43 PM Jeff Layton wrote: > > > > > > What sort of big, ugly warning did you have in mind? > > > > I originally thought WARN_ON_ONCE() just to get the distro automatic > > error handling involved, but it would probably be a big problem for > > the people who end up having panic-on-warn or something. > > Even panic-on-oops is a PITA. > Took us weeks to realise that a customer system that was randomly > rebooting was 'just' having a boring NULL pointer access. > > > So probably just a "make it a big box" thing that stands out, kind of > > what lockdep etc does with > > > > pr_warn("======...====\n"); > > > > around the messages.. Do we really need more of these? They take time to print (especially on serial consoles) and increase kernel size. What's wrong with using an appropriate KERN_*, and letting userspace make sure the admin/user will see the message (see below)? > > > > I don't know if distros have some pattern we could use that would end > > up being something that gets reported to the user? > > Will users even see it? > A lot of recent distro installs try very hard to hide all the kernel > messages. Exactly. E.g. Ubuntu doesn't show any kernel output during normal operation. On Fri, Aug 20, 2021 at 6:12 PM Linus Torvalds wrote: > On Fri, Aug 20, 2021 at 6:43 AM Steven Rostedt wrote: > > On Thu, 19 Aug 2021 15:32:31 -0700 > > Linus Torvalds wrote: > > > > > > I don't know if distros have some pattern we could use that would end > > > up being something that gets reported to the user? > So what would be more interesting is if there's some distro support > for showing kernel notifications.. > > I see new notifications for calendar events, for devices that got > mounted, for a lot of things - so I'm really wondering if somebody > already perhaps had something for specially formatted kernel > messages.. Isn't that what the old syslog and the new systemd are supposed to handle in userspace? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds