Re: [PATCH v1 1/2] kbuild: Mark the kernel image gzip recipes as recursive

[Lorenzo Stoakes (ARM)]

On Thu, Oct 08, 2026 at 11:27:30PM -0700, Kees Cook wrote:
> Since commit 48ebe1cbbeb51 ("kbuild: compress the kernel with pigz if
> available"), cmd_gzip runs pigz through scripts/jobserver-exec, which
> takes the job slots make has free. GNU Make passes the jobserver pipe
> only to recipes it treats as recursive, but leaves --jobserver-auth in
> MAKEFLAGS for all of them. The make 4.3 in CentOS Stream 9 also hides
> the pipe in sub-makes (a backport of the fix for GNU Make bug 58232), so
> jobserver-exec cannot open it, runs pigz on one thread, and prints:
>
>   WARNING: Unable to reopen jobserver read-side pipe: FileNotFoundError(2, 'No such file or directory')
>
> Mark the gzip recipes as recursive with "+", as commit ecab4115c44cc
> ("kbuild: mark `rustc` (and others) invocations as recursive") did for
> rustc. As with those, "make -n" now runs them.
>
> Tested ARCH=x86_64 and ARCH=arm64 defconfig with GNU Make 4.3 plus
> CentOS Stream 9's make-4.3-cloexec.patch, GCC 16.2.0, and -j64: without
> this change the warning appears and pigz runs with "-p 1"; with it there
> is no warning, and pigz runs with "-p 54" and "-p 64".
>
> Reported-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> Closes: https://lore.kernel.org/all/0ddb5e5e-f801-444c-aa98-0cfe814a3026@paulmck-laptop/
> Fixes: 48ebe1cbbeb51 ("kbuild: compress the kernel with pigz if available")
> Assisted-by: LLM
> Signed-off-by: Kees Cook <kees@xxxxxxxxxx>

Nice find!

Acked-by: Lorenzo Stoakes (ARM) <ljs@xxxxxxxxxx>

Sorry for breaking your build Paul ;)

--
Cheers, Lorenzo