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Thu, 21 Nov 2024 10:30:01 -0800 (PST) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2129dc2aad7sm1310415ad.279.2024.11.21.10.30.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Nov 2024 10:30:01 -0800 (PST) Date: Thu, 21 Nov 2024 10:30:00 -0800 From: Guenter Roeck To: "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 Subject: Re: [PATCH] slab: Fix too strict alignment check in create_cache() Message-ID: 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <693a6243-b2bd-7f2b-2b69-c7e2308d0f58@gentwo.org> X-Rspamd-Server: rspam10 X-Stat-Signature: ho9zxwupbskubdnyywhrkj9xxm4he8pi X-Rspamd-Queue-Id: 19BB8C000A X-Rspam-User: X-HE-Tag: 1732213779-292573 X-HE-Meta: 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 SitODEWQ gOPyMWx5/Q/6yKdOAgQ3riL/EfSBkZt2DzxdTJ5TO7/uHihMEgGIHcuBxdVH1ArcKlGEdnFz2Z1SEI3XLBrJfnPM43x8dkI1SY7I5+iHPyfKiVG80nBbcWgTOcXhgLypOqYx8jzyR2efu23WJXUGMs51jel+PbmHw9jtjeaBVqc0jsh6kxvqO46vKFVKW7OiuRx2BS2Q2iyCTEnAn+0jOiZK9cuHLx05J9rSb0sZ2yHe5TmA/lxRaO01/Gz+yLXCtkSAzWTvia6pZA7+jOJAeoVaj5wmlnOhel3mvA9Q/lEJDIuAX0y8QuNAQvNzF/keK7EjbflUmgQEeCyeWIAH1VF9xJQpgS1zHjQ1zQcRJtVhDHF4aFWS7BFAG5H2+Zyw8ok8tG7OfC8lzz19FjUH/Szef89PlEIsirTumLSIDb+ZzGDslj+fL7tDbJwfs9MBDW7XO5HjrffITSWayBKeXfRdI5onM2N97J1w7EhplyiD85VlVdlOyjGv73c5QrBNmcskb/2UoKbrcjoLBJHgOqS7tb0PiFdhvJ0kk6Tl+SBtzdDMXAjnl+2Mo6m8BABWoh2wJpZmV9HzkH/DqI4vLyNlUEN5ia4F07q+sMxHqavi//XP8MKxZp305ew== 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 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 ? Guenter