linux-kernel - Re: [PATCH] atomic: Specify natural alignment for atomic

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Message-ID: <312ba353-6b4e-c3ef-40ce-a9dddf3275a3@linux-m68k.org>
Date: Wed, 27 Aug 2025 18:00:43 +1000 (AEST)
From: Finn Thain <fthain@...ux-m68k.org>
To: Lance Yang <lance.yang@...ux.dev>
cc: David Laight <david.laight.linux@...il.com>, akpm@...ux-foundation.org, 
    geert@...ux-m68k.org, linux-kernel@...r.kernel.org, mhiramat@...nel.org, 
    oak@...sinkinet.fi, peterz@...radead.org, stable@...r.kernel.org, 
    will@...nel.org, Lance Yang <ioworker0@...il.com>
Subject: Re: [PATCH] atomic: Specify natural alignment for atomic_t


On Mon, 25 Aug 2025, Lance Yang wrote:

> > 
> > More problematic is that, IIRC, m68k kmalloc() allocates 16bit aligned 
> > memory. This has broken other things in the past. I doubt that 
> > increasing the alignment to 32bits would make much difference to the 
> > kernel memory footprint.
> 
> @Finn Given this new information, how about we just apply the runtime 
> check fix for now?

New information? No, that's just hear-say.

> Since we plan to remove the entire pointer-encoding scheme later anyway, 
> a minimal and targeted change could be the logical choice. It's easy and 
> safe to backport, and it cleanly stops the warnings from all sources 
> without introducing new risks - exactly what we need for stable kernels.
> 

Well, that's up to you, of course. If you want my comment, I'd only ask 
whether or not the bug is theoretical (outside of m68k).