Occasional hung with UM after enable VMAP_STACK

[Walter Lozano]

Hi all,

I noticed that after "um: enable VMAP_STACK" [1] I experienced some 
occasional hung in my Gitlab CI jobs that use user-mode-linux to build 
distro images. The configuration use for the building is the one 
available from Debian, see [2] and [3]. Unfortunately I don't have much 
information, when the issue arises the job seems to hang and it is 
cancelled by Gitlab due to a job timeout.

So far I did some bisect to get the commit which introduces the issue 
and a quick check with latest Linux stable branch master to confirm the 
issue is still present. I know this is not a proper bug report but I 
thought it will be better to at least raise a comment.

Thanks in advance,

Walter

[1] http://lists.infradead.org/pipermail/linux-um/2021-August/001657.html

[2] https://packages.debian.org/bookworm/user-mode-linux

[3] https://salsa.debian.org/uml-team/user-mode-linux

--
Walter Lozano
Collabora Ltd.