linux-kernel - Re: [PATCH v2] fork: stop ignoring NUMA while handling cached thread stacks

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CACRpkdYwUAEvqLugyHfAaHqUXODq+4kdKphgfxs7-UJMaAYeag@mail.gmail.com>
Date: Thu, 20 Nov 2025 14:09:07 +0100
From: Linus Walleij <linus.walleij@...aro.org>
To: Mateusz Guzik <mjguzik@...il.com>
Cc: akpm@...ux-foundation.org, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org, pasha.tatashin@...een.com, 
	Liam.Howlett@...cle.com, lorenzo.stoakes@...cle.com
Subject: Re: [PATCH v2] fork: stop ignoring NUMA while handling cached thread stacks

On Thu, Nov 20, 2025 at 6:40 AM Mateusz Guzik <mjguzik@...il.com> wrote:

> 1. the numa parameter was straight up ignored.
> 2. nothing was done to check if the to-be-cached/allocated stack matches
>    the local node
>
> The id remains ignored on free in case of memoryless nodes.
>
> Note the current caching is already bad as the cache keeps overflowing
> and a different solution is needed for the long run, to be worked
> out(tm).
>
> Stats collected over a kernel build with the patch with the following
> topology:
>   NUMA node(s):              2
>   NUMA node0 CPU(s):         0-11
>   NUMA node1 CPU(s):         12-23
>
> caller's node vs stack backing pages on free:
> matching:       50083 (70%)
> mismatched:     21492 (30%)
>
> caching efficiency:
> cached:         32651 (65.2%)
> dropped:        17432 (34.8%)
>
> Signed-off-by: Mateusz Guzik <mjguzik@...il.com>

Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

Yours,
Linus Walleij