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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id u22sm7302162pfi.143.2021.08.20.09.30.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Aug 2021 09:30:32 -0700 (PDT) Date: Fri, 20 Aug 2021 09:30:31 -0700 From: Kees Cook To: Linus Torvalds Cc: Jeff Layton , "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 , 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 Subject: Re: Removing Mandatory Locks Message-ID: <202108200905.BE8AF7C@keescook> References: <87eeay8pqx.fsf@disp2133> <5b0d7c1e73ca43ef9ce6665fec6c4d7e@AcuMS.aculab.com> <87h7ft2j68.fsf@disp2133> <87k0kkxbjn.fsf_-_@disp2133> <0c2af732e4e9f74c9d20b09fc4b6cbae40351085.camel@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b="AHhWe/b1"; dmarc=pass (policy=none) header.from=chromium.org; spf=pass (imf20.hostedemail.com: domain of keescook@chromium.org designates 209.85.215.172 as permitted sender) smtp.mailfrom=keescook@chromium.org X-Stat-Signature: pa66k7y6k3bcpuhj74zyctqzp8f8g6is X-Rspamd-Queue-Id: 2A183D0000B2 X-Rspamd-Server: rspam01 X-HE-Tag: 1629477034-374540 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 Thu, Aug 19, 2021 at 12:15:08PM -0700, Linus Torvalds wrote: > On Thu, Aug 19, 2021 at 11:39 AM Jeff Layton wrote: > > > > I'm all for ripping it out too. It's an insane interface anyway. > > > > I've not heard a single complaint about this being turned off in > > fedora/rhel or any other distro that has this disabled. > > I'd love to remove it, we could absolutely test it. The fact that > several major distros have it disabled makes me think it's fine. FWIW, it is now disabled in Ubuntu too: https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/impish/commit/?h=master-next&id=f3aac5e47789cbeb3177a14d3d2a06575249e14b > But as always, it would be good to check Android. It looks like it's enabled (checking the Pixel 4 kernel image), but it's not specifically mentioned in any of the build configs that are used to construct the image, so I think this is just catching the "default y". I expect it'd be fine to turn this off. I will ask around to see if it's actually used. -- Kees Cook