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b=pbprpurr8gstgLWvynRh4gN3SAZyj677O93nF23T9qO34OFlTgSrJsI8/uUcvUIes O6tsINdL98/x3LSSQDZqJmLnC8vmi5C46OgAIaYkGbWxrcRq2UVRhgBFnlhEcUwaOU RFdFRd1JKeu0cKZCjdtry4IUpWxmx2Vr5W5ptofcojHJF6Dq1tCXBCZW9LYmUY76/G dcmAyQmAsS/DpYuw5qDXuX7fvXhqXqI4l54z2zHBZ8oBuQQ7H7qTb1swv9zN8NsefB 2SqT8869FtEnzICbW5HYwZBO2IrRzKmKL7oUq8H6UTlxwEeZ42zplti8uWeqcY7ZnY 9LEMFpFWjPXpA== Message-ID: <858dbafa-6320-4603-82b9-38f586f18249@kernel.org> Date: Fri, 22 Nov 2024 10:23:26 +1000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] slab: Fix too strict alignment check in create_cache() To: Guenter Roeck , "Christoph Lameter (Ampere)" Cc: Geert Uytterhoeven , Vlastimil Babka , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Jens Axboe , Pavel Begunkov , Mike Rapoport , Christian Brauner , Kees Cook , Jann Horn , linux-mm@kvack.org, io-uring@vger.kernel.org, linux-m68k@vger.kernel.org, linux-kernel@vger.kernel.org References: <80c767a5d5927c099aea5178fbf2c897b459fa90.1732106544.git.geert@linux-m68k.org> <4f70f8d3-4ba5-43dc-af1c-f8e207d27e9f@suse.cz> <2e704ffc-2e79-27f7-159e-8fe167d5a450@gentwo.org> <693a6243-b2bd-7f2b-2b69-c7e2308d0f58@gentwo.org> Content-Language: en-US From: Greg Ungerer In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 9D1B014001A X-Rspamd-Server: rspam01 X-Stat-Signature: cfccdpf6goq6ifb4a9hsky7mrdne544g X-HE-Tag: 1732234974-58025 X-HE-Meta: U2FsdGVkX1/dUwRca0WzCxKw8NI3Mh9I9v+W8+ZuVuEaVxyowvk/OBkQPtN+h8b6GeThW3ygGxcZiaHsdC+0bgwqouh72u/pWdeNXNqDjIf+S8nL3JtvViZYpdNY44tJDIoIkWEjqfcMl8ooeiZNobCCYPa97B+kRKoOlR7tsL6yy1Td2lTzParVuCEdkkngDqbt+iuD2RVA2/OwaZyqnri2e3hM+6R+3CmZV89qkjgYDmWWWLL3SqObR8PBHuFmkxwjXSctgoW4q8FEY84DnqOSwy0NVtUyJnIXV/87nugC2eps/qxpyFg9xkClzL8M511x6WyeVW88X5LKwPnYK+P1cMepTo+OgSbqA/aPXc5UeS7lfAepul4la9IJNj0/pADeTO6dV6AUeCCrAAuZ44bzFxEAkBXac2Xu1jXDOxWeHJqnMFSkMjymDxBkpM1hBRy6TG/tDRzRIGpJVKO9nFQKanFEMVHl0tQvPGQL1S4pVqVv2pW6NILLldd0sDRaoM/6ZM9hmcOhHn3Go613KH52pxnKREB/TuPiJmRkjqXRoLQzURMAZnNe84Q2dZOm55Y/2Nv1HadRLsM9MlYKrMkF13UjTlUT+EObSpKWxDT/n5ATGNzi0lQbL00R9S1uI7JJqfXdCWFzZPvTzNcCQSL31SFc+nN/OiI9DzI5C4TJc6aPL7L/2cFTKBeKsMrO+bbv2vqH68ZXSgDip7ccdv0rhUzqeZsscRv/0k0KXCvh1kXhQN1COgTB3VMWRmSlGBkW+oURZLTTtESGd2p3Eg8yG4N66sCiXx3GfhBOCO8hkGzNC5pG1HN3BYLPAefejObx3KGAlYbQDx3hk7bV25ydTTqRGUiFtJmMryieN0XCCyRarr+ivuNuTfcX1dC1w570IT7uC2yBaCpIdhwaNUPrhaGMQeprErkWkGNFB969EyjrAENJBTE89P9oG87UOvOAdssMsL7O5HYAcNA 9FPzYfw9 EO9VrnQYHOz2Mw0C3bPXBadj71KzNZwMpvjtX6ALIoEvUMy40rTRSOljd+wN/5F6cjpNZcq6i5G9OpSwRCfXNPz3EL6IH3VGqY9658bgESAh8/NbHjbnWPUdWIY8bS27w5nMlioRPLGDSbu77VFQmqj9A/A/UtfF+xnpyb49GzWdcIES+iAndFDs/XDuWARr6WJfmK8kdZkE4e6RbACXB4GapA6EY1z25fsL/jSCRTk1uAsdHTXaE2i1XoY5r0Vk7YpmEI0t6faCp9T5OSTBsN1ijqYoT8ZkIO3hXz+Mq9mruiuALKp98ToXR8AwfVei5EjircfbXrmuhLyUkKI3ZjhcxSKdIQam1JcMTWSBxxkYvfboagm88dEfpFGElgh7yeIcu 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: List-Subscribe: List-Unsubscribe: On 22/11/24 04:30, Guenter Roeck wrote: > On Thu, Nov 21, 2024 at 09:23:28AM -0800, Christoph Lameter (Ampere) wrote: >> On Thu, 21 Nov 2024, Geert Uytterhoeven wrote: >> >>> Linux has supported m68k since last century. >> >> Yeah I fondly remember the 80s where 68K systems were always out of reach >> for me to have. The dream system that I never could get my hands on. The >> creme de la creme du jour. I just had to be content with the 6800 and >> 6502 processors. Then IBM started the sick road down the 8088, 8086 >> that led from crap to more crap. Sigh. >> >>> Any new such assumptions are fixed quickly (at least in the kernel). >>> If you need a specific alignment, make sure to use __aligned and/or >>> appropriate padding in structures. >>> And yes, the compiler knows, and provides __alignof__. >>> >>>> How do you deal with torn reads/writes in such a scenario? Is this UP >>>> only? >>> >>> Linux does not support (rate) SMP m68k machines. >> >> Ah. Ok that explains it. >> >> Do we really need to maintain support for a platform that has been >> obsolete for decade and does not even support SMP? > > Since this keeps coming up, I think there is a much more important > question to ask: > > Do we really need to continue supporting nommu machines ? Is anyone > but me even boot testing those ? Yes. Across many architectures. And yes on every release, and for m68k building and testing on every rc for nommu at a minimum. I rarely hit build or testing problems on nonmmu targets. At least every kernel release I build and test armnommu (including thumb2 on cortex), m68k, RISC-V and xtensa. They are all easy, qemu targets for them all. Thats just me. So I would guess there are others building and testing too. But what has that got to do with this thread, seems somewhat tangential to the discussions here so far... Regards Greg