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Thu, 21 Nov 2024 11:08:52 -0800 (PST) Date: Thu, 21 Nov 2024 11:08:51 -0800 From: Guenter Roeck To: Geert Uytterhoeven Cc: "Christoph Lameter (Ampere)" , 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: <508aa9c4-4176-4336-8948-a31f9791dd39@roeck-us.net> 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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspam-User: X-Rspamd-Queue-Id: 0B25C14000E X-Rspamd-Server: rspam11 X-Stat-Signature: xf4myksw11hxpkmx184j5sc8dtmkqkmw X-HE-Tag: 1732216094-206483 X-HE-Meta: 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 pshBR5Wd 20K0kAXo+RrYZJoLXLELVHopQ5PjjOKOE4Aa913dYlKQXkXIPq1659HWk7yc13BhjwTnwh30isQLwT+gHJoZBR3RMtB+2lw4r+8ydNKqF4aDHYBldcYJNP31EmSBFijO5waAtW/MWV/MkdPxvRf8zexvb6hR4bv1Mw+/4Fk9VpJX266eScC4XBoXbbSEw22A6lcVdIu3UnFKRasBEMY+bBcu4ZQoKAfNLbGv3uGt7eq1aC3B3CRRU6CtUPLY9mTMcpQKlm7rdKfSpaF4iQo55EAjT9ZluFshZNjV1a74RN0WOHy5JirStuGzznzDNlWDHXLW418AEYkwDSNNvj4hGAi35C7G7ohd6o8LZEDd026EQ5CM+0v1HWyjeAvnUmWYF7zodDv67T/bxLvBHk7Acwoi8NGSRvMj1AfHVu5r3XkBLQZ6CuHRODPKMWYmorn0MHXK+MofhqdCjcDeUu1JOcaPzuDGE/SsrjbVzFm6xWHSUBSFZIMl/kq27z3iFrByBNda6ruLXREq4a0MJYxqWU2uVZHMaWdaacoQ1N4cvcE5sNq6E+bIjXaU3d19cmaPrArJjYydlarKSayFUIG+g+vWz7mPQ77LNggbLgRoIDHRT4Df9pUkGvMfdVndjRTWmPpRYYGS7lE1Uzwob7a9H51KTTZFvwaNgLeJnENNHhmNzQyo= 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 07:50:33PM +0100, Geert Uytterhoeven wrote: > On Thu, Nov 21, 2024 at 7:30 PM 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. > > s/rate/rare/ > > > > 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 ? > > Not all m68k platform are nommu. > Yes, I wasn't trying to point to m68k, but to nommu in general. Guenter