Re: [BUG] Build failure in next-20261007 and next-20261008

[Kees Cook <kees@kernel.org>]

On Thu, Oct 08, 2026 at 05:56:21PM -0700, Paul E. McKenney wrote:
> Building a kernel on CentOS Stream 9 from next-20261007 and next-20261008
> (and maybe others?)  on an x86 or arm64 system results in a strange
> build failure featuring:
> 
> WARNING: Unable to reopen jobserver read-side pipe: FileNotFoundError(2, 'No such file or directory')

What are your make and python versions? (Oh, the answer is going to be
"CentOS-patched make 4.3")

> The failing systems have a pigz command (which complains bitterly when
> run without arguments), and the immune system does not.  On the failing
> systems, "pigz --version" gives me "pigz 2.5".
> 
> Do I need a specific version of pigz?  Does this commit need a
> version-number check?  Are my systems pigz-intolerant?  ;-)
> 
> Less flippantly, is this a known problem?  If not, what debugging
> information can I provide?

Having pigz just means the parallelism logic kicks in, so I'm suspecting
something in scripts/jobserver-exec. That would point to something
specific to python or make.

I haven't seen this reported before, no.

Ah, and before I could even finish writing this email, my ever helpful
LLM has reported: "pre-4.4 make (like CentOS's 4.3) closes jobserver
pipe descriptors in non-recursive recipes but still exports
--jobserver-auth=R,W via MAKEFLAGS, whereas 4.4+ uses a named FIFO
instead, explaining why it doesn't appear here." And has further found
that this is CentOS-specific, since they appear to have incorrectly
backported a patch ("make-4.3-cloexec.patch"), as stock make 4.3 doesn't
have this problem.

I'll go figure out if there is some proper way to work around CentOS's
broken make...

(And given this, I would suspect you can't do a '-j...' build of the
"htmldocs" target either?)

-Kees

-- 
Kees Cook