netdev - [REGRESSION] in 6.17, failing __dev_change_net

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Message-ID: <01070199e22de7f8-28f711ab-d3f1-46d9-b9a0-048ab05eb09b-000000@eu-central-1.amazonses.com>
Date: Tue, 14 Oct 2025 10:04:43 +0000
From: Cynthia <cynthia@...mx.dev>
To: netdev@...r.kernel.org
Subject: [REGRESSION] in 6.17, failing __dev_change_net_namespace+0xb89/0xc30

When I updated my machine to the newest kernel, a bug started to appear. 
The system does not panic, but an error kept happening in dmesg.

The bug happens with LXC/Incus when it tries to start a new container. 
(but probably other things are affected too)

Steps to Reproduce: the bug can be reproduced in a libvirt VM, no need 
for a specific system. Also I suspect the bug is also 
architecture-independent, but I cannot verify that.
1) Install ArchLinux (all dependencies are available). I was testing 
with vanilla kernel, so any linux distro should be affected.
https://aur.archlinux.org/packages/linux-mainline can be installed, this 
is the vanilla kernel with a generally good kernel config for most PCs.
2) Install LXC/Incus (pacman -S incus)
3) configure incus and start a container:
usermod -v 1000000-1000999999 -w 1000000-1000999999 root &&
incus admin init &&
incus launch images:debian/12 first # start a container
4) Previous step should trigger incus to do namespaces. I'm not sure 
what syscall is causing the bug, I do not have a mini C program. These 
steps should be enough to see the log in the dmesg.

I also did a git bisect, the first commit to have this bug is this:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0c17270f9b920e4e1777488f1911bbfdaf2af3be

I initially reported this bug on Bugzilla, but after seeing 6 year old 
bugs there, I'm not sure if that platform is still in use.
https://bugzilla.kernel.org/show_bug.cgi?id=220649

Since my initial report, 6.17.2 was released, the bug is still happening.

I'm attaching 2 files:
dmesg_slice: the slice of dmesg containing the problematic frame (on a 
bare-metal linux with AMD srso mitigation disabled)
bisect_log: a log of the git bisect process

View attachment "bisect_log" of type "text/plain" (2884 bytes)

View attachment "dmesg_slice" of type "text/plain" (6832 bytes)