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=-6.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 DF1D2C43214 for ; Fri, 20 Aug 2021 13:03:25 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8187F610CC for ; Fri, 20 Aug 2021 13:03:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 8187F610CC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 13E548D0001; Fri, 20 Aug 2021 09:03:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0C6D46B0072; Fri, 20 Aug 2021 09:03:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EF7148D0001; Fri, 20 Aug 2021 09:03:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0180.hostedemail.com [216.40.44.180]) by kanga.kvack.org (Postfix) with ESMTP id D2CD66B0071 for ; Fri, 20 Aug 2021 09:03:24 -0400 (EDT) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 7FE462C6B2 for ; Fri, 20 Aug 2021 13:03:24 +0000 (UTC) X-FDA: 78495475128.16.CAC5C9F Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf23.hostedemail.com (Postfix) with ESMTP id 1ED3D900009B for ; Fri, 20 Aug 2021 13:03:23 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 1CE066101A; Fri, 20 Aug 2021 13:03:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629464603; bh=vpNTkAzVtAqymBqf9jS7V0ipLd6rQmU/JReC+oGFdAc=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=dcmDtzTWNKoJjA2+EvxNaxCDTp6LXJ+l4+Nxo5lPDGZVYmdo6z25/cf8Y52TQoPeg /OaGgxa6731NwYc2cBjOqjtBOmVtx9qTOjvEdyD/niq3e2rM8DmLpQWpD0F15jfOGa aRSKZKt37z+SvrwWc2DbPhpw2GOD6fZwGW2OrSeyc+kNck5EaM5u+Cz0RYLeSE8V8u 5Fb/hprjZ09rwsUTRawi7poo+XS03wfXu5Go4jg8Ms4bZFM+m/MxekI54ydGbKfSaB 2w4QT70SWxhJKE3D8F7+dtojw9i/oBolVHciomvz6JXltJUbDo73S1fmcmOsvUCYJa gmPSD4WulbnYQ== Message-ID: <765d446cc4190575ab400a3a8038db658196b4bf.camel@kernel.org> Subject: Re: Removing Mandatory Locks From: Jeff Layton To: Willy Tarreau Cc: Amir Goldstein , Linus Torvalds , "Eric W. Biederman" , Matthew Wilcox , Andy Lutomirski , David Laight , 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 , Geert Uytterhoeven , 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 , Christian =?ISO-8859-1?Q?K=F6nig?= , "linux-unionfs@vger.kernel.org" , Linux API , the arch/x86 maintainers , "" , Linux-MM , Florian Weimer , Michael Kerrisk Date: Fri, 20 Aug 2021 09:03:16 -0400 In-Reply-To: <20210820123810.GE22171@1wt.eu> References: <87k0kkxbjn.fsf_-_@disp2133> <0c2af732e4e9f74c9d20b09fc4b6cbae40351085.camel@kernel.org> <20210820123810.GE22171@1wt.eu> Content-Type: text/plain; charset="ISO-8859-15" User-Agent: Evolution 3.40.4 (3.40.4-1.fc34) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=dcmDtzTW; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf23.hostedemail.com: domain of jlayton@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=jlayton@kernel.org X-Stat-Signature: 6djy471dx7wh3tgjq8k74yd7n7yjbcyt X-Rspamd-Queue-Id: 1ED3D900009B X-Rspamd-Server: rspam05 X-HE-Tag: 1629464603-13311 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, 2021-08-20 at 14:38 +0200, Willy Tarreau wrote: > On Fri, Aug 20, 2021 at 08:27:12AM -0400, Jeff Layton wrote: > > I'm fine with any of these approaches if the consensus is that it's too > > risky to just remove it. OTOH, I've yet to ever hear of any application > > that uses this feature, even in a historical sense. > > Honestly, I agree. Some have fun of me because I'm often using old > stuff, but I don't even remember having used an application that > made use of mandatory locking. I remember having enabled it myself in > my kernels long ago after discovering its existence in the man pages, > just to test it. It doesn't rule out the possibility that it exists > somewhere though, but I think that the immediate removal combined > with the big fat warning in previous branches should be largely > enough to avoid the last minute surprise. > Good point. It wouldn't hurt to push such a warning into stable kernels at the same time. There always is a lag when we do something like this before some downstream user notices. -- Jeff Layton