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 4338EC4320A for ; Mon, 23 Aug 2021 07:56:11 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DBB8C610FF for ; Mon, 23 Aug 2021 07:56:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org DBB8C610FF Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-m68k.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 322D66B006C; Mon, 23 Aug 2021 03:56:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2D3EC6B0072; Mon, 23 Aug 2021 03:56:10 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 19B1B8D0001; Mon, 23 Aug 2021 03:56:10 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0093.hostedemail.com [216.40.44.93]) by kanga.kvack.org (Postfix) with ESMTP id 01CE76B006C for ; Mon, 23 Aug 2021 03:56:09 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 80FBC26822 for ; Mon, 23 Aug 2021 07:56:09 +0000 (UTC) X-FDA: 78505587258.05.B7160CE Received: from mail-vs1-f43.google.com (mail-vs1-f43.google.com [209.85.217.43]) by imf12.hostedemail.com (Postfix) with ESMTP id 3579D10000AB for ; Mon, 23 Aug 2021 07:56:09 +0000 (UTC) Received: by mail-vs1-f43.google.com with SMTP id k24so10498380vsg.9 for ; 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=kY+FQj73vj81/2pRBhhr7Kdx3riVeSIPc7nH2BtzBoSrMwe2YVpPsJDNaq+RZ5wbNt n5JqPXXOJN9vQPPCXZXRdVagco6YTpVwZYbFYtp2beZqKHyV7IE8JvAqq2p10LVNeuBY nTSLvEQhN6fcqfAKwW6Jv7Ylnt56rCiGpMvWQfX4M2jVci/JxX9M3R+BWcP9/PEE1yFt cVBiqbuIEIaEHDioDnbSzPAfCDg7bnHUcCJU1p4ryZ+VTYszCrtoI0EMrtnwfd7pmBM4 QQt4cMHbpfVhmwFHUJ+SQY7jTbUJFdLyOYdochX0WXQKERiqkIHJjv4IKwdalDR3Gc4/ zV3Q== X-Gm-Message-State: AOAM530BTN/vt4yjvnvMJMUfY1Fi+JK4s3gUJme+05W8ZtdB0ood8eKf ZhmSt02az4Jwxb4Pcb60pQws0fnrBHgENUoPrHo= 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" Authentication-Results: imf12.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf12.hostedemail.com: domain of geertuytterhoeven@gmail.com designates 209.85.217.43 as permitted sender) smtp.mailfrom=geertuytterhoeven@gmail.com X-Stat-Signature: 8n7x4a4om81ihn8auu4db46a7g56caxp X-Rspamd-Queue-Id: 3579D10000AB X-Rspamd-Server: rspam04 X-HE-Tag: 1629705369-920013 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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