Subject: Re: bug#72278: 29.4; Proced reports incorrect results with 16KB page size

From: Paul Eggert <[email-masked]>
Date: Fri, 26 Jul 2024 18:40:30 -0700

On 2024-07-26 15:33, Stefan Kangas wrote:
> Paul Eggert<[email-masked]> writes:
> 
>> On 2024-07-25 02:55, Stefan Kangas wrote:
>>> On Linux, page sizes can vary per process ("multiple page size
>>> support").  Should we bother with that?
>> I thought that support didn't change what getpagesize returns or what
>> /proc/PID/stat reports, at least not in mainline Linux kernels. Am I
>> missing something?
> I don't know to be honest, which is why I'm asking.

For recent Asahi Linux user-mode pages are always 16 KiB; see 
<https://github.com/AsahiLinux/docs/wiki/Broken-Software>.

I'd be surprised if any Linux distro lets getpagesize calls differ among 
processes running atop the same kernel. Although Linux does support huge 
pages via (for example) mmap with MAP_HUGETLB, I would expect this to 
not affect getpagesize or /proc/PID/stat. I haven't verified this by 
running code or by scouting through kernel source, though.