Re: [PATCH 0/3] umount fixes and cleanups

[Jan Kiszka <jan.kiszka@siemens.com>]

On 05.12.18 12:12, Maxim Yu. Osipov wrote:
> On 12/5/18 12:29 PM, Jan Kiszka wrote:
>> Patches related to resolving the pending CI issues as well as
>> simplifying the umounts used during cleanup.
> 
> Tried to run in patch queue:
> 
> 027b7cf Remove redundant recursive umounts
> c1bdc33 isar-events: Improve umount handler
> b354273 ci: Wait for bitbake worker to finish before deleting artifacts
> 9cf29e6 isar-bootstrap: Fix and cleanup bind mounting
> b354026 isar-image: umount base-apt when doing offline build
> e965c0d gitlab-ci: Switch to ci_build.sh
> ...
> 
> After execution of problematic test case (I rebooted PC and executed steps in 
> clean tree):
> 
> my stretch Debian system was entered into unusable state
> as many important mounts were disappeared (see log of mount points
> before and after execution  of last command attached).

OK, so I took the time and extracted the root cause. We may see a Debian 4.9 
kernel bug here:

# mkdir my-mnt
# mount --rbind /sys my-mnt
# mount --make-rslave my-mnt
# umount {-R,-l,-R -l} my-mnt
# rmdir my-mnt
rmdir: failed to remove 'my-mnt': Device or resource busy

This works fine on my Leap 15.0 kernel (4.12) as well as the 4.4 kernel (Ubuntu) 
used on our CI server.

*This* is information we can base commits on. Also, we can file a bug against 
Debian with this. Could you do that (keep my in CC)?

Thanks,
Jan

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