From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5A40715A8; Fri, 22 Nov 2024 00:23:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732235014; cv=none; b=d7ttB+Vb/PG028BFvsUmmbHVQmZVdIFov9LDubXK8yMKKYFiR50PL+vB+pZJkKV8Fnq7WqmUygPV9QKUO3TurdSmL5/ZaNevDP/Zzozl9rRVBNDWdaeEn16yyh7FJiSCXuQg2vsW5HdK3ybLQ7TmI3X7W14Ol+mWCtTrZwzhIBk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732235014; c=relaxed/simple; bh=+QH/OYcCJQTHkWDi9Mz3wZ7DEIXig5j4yU+JGy8razE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=mBmAXvjXDIq0/hciBZOuTgiJx1f3qy+22jhqbMPPWgefqGNq27/h4nue0Dcx3uVzDedt6X/3DWWCRg8VWnPV+2YZHTo8yx+oP+NYi9JJHPNE9rYcAr1icVQ3bfQjYrM3ZoCLkbrGfQmB9U/GbvQntIFGG44VOWdQcCNcCV9+1BI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pbprpurr; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="pbprpurr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B69A0C4CECC; Fri, 22 Nov 2024 00:23:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1732235013; bh=+QH/OYcCJQTHkWDi9Mz3wZ7DEIXig5j4yU+JGy8razE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; 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 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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