Re: Commit *pidfd: prevent creation of pidfds for kthreads* causes `Failed to remount '/' read-only: Device or resource busy`

From: Paul Menzel
Date: Tue Aug 20 2024 - 01:31:48 EST


Dear Thorsten,


Am 20.08.24 um 07:03 schrieb Thorsten Leemhuis:
On 19.08.24 23:02, Paul Menzel wrote:
#regzbot introduced: 3b5bbe798b24

Commit 3b5bbe798b24 (pidfd: prevent creation of pidfds for kthreads)
causes a regression. On the Dell XPS 13 9360 with Debian sid/unstable
and *systemd* 256.5-1, systemd is not able to unmount the root partition
(LUKS encrypted) anymore.

Hi Paul! Thx for the report. FWIW, a revert to fix this is already
queued as 780d60bac21ebe ("Revert "pidfd: prevent creation of pidfds for
kthreads"") [next-20240820 (pending-fixes)] after Eric reported similar
problems recently:

https://lore.kernel.org/all/20240819-staudamm-rederei-cb7092f54e76@brauner/

Thank you for digging this up. I thought I search for the commit hash in lore.kernel.org, but maybe I hit the wrong button *locate inbox*.

Anyway, reverting the patch on top of master also fixes the issue for me. Maybe Linus can take it directly, as more people are going to run into this.


Kind regards,

Paul