Re: [PATCH stable 5.15 0/2] kbuild: Fix compilation for latest pahole release

From: Nathan Chancellor <nathan@kernel.org>
To: Jiri Olsa <olsajiri@gmail.com>
Cc: Greg KH <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, bpf@vger.kernel.org,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Martin Rodriguez Reboredo <yakoyoku@gmail.com>,
	Andrii Nakryiko <andrii@kernel.org>
Subject: Re: [PATCH stable 5.15 0/2] kbuild: Fix compilation for latest pahole release
Date: Mon, 17 Oct 2022 11:02:39 -0700	[thread overview]
Message-ID: <Y02Yv/ubuCtVhtZk@dev-arch.thelio-3990X> (raw)
In-Reply-To: <YyeYUEHyR/nHM8NT@krava>

On Mon, Sep 19, 2022 at 12:14:40AM +0200, Jiri Olsa wrote:
> On Tue, Sep 06, 2022 at 02:03:30PM +0200, Greg KH wrote:
> > On Mon, Sep 05, 2022 at 09:04:10AM +0200, Jiri Olsa wrote:
> > > On Sun, Sep 04, 2022 at 04:10:09PM +0200, Greg KH wrote:
> > > > On Sun, Sep 04, 2022 at 03:18:59PM +0200, Jiri Olsa wrote:
> > > > > hi,
> > > > > new version of pahole (1.24) is causing compilation fail for 5.15
> > > > > stable kernel, discussed in here [1][2]. Sending fix for that plus
> > > > > one dependency patch.
> > > > > 
> > > > > Note for patch 1:
> > > > > there was one extra line change in scripts/pahole-flags.sh file in
> > > > > its linux tree merge commit:
> > > > > 
> > > > >   fc02cb2b37fe Merge tag 'net-next-for-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
> > > > > 
> > > > > not sure how/if to track that, I squashed the change in.
> > > > 
> > > > Squashing is fine, thanks.
> > > > 
> > > > And do we also need this for kernels older than 5.15?  Like 5.10 and 5.4?
> > > 
> > > yes, 5.10 needs similar patchset, but this for 5.15 won't apply there,
> > > so I'll send it separately
> > > 
> > > 5.4 passes compilation, but I don't think it will boot properly, still
> > > need to check on that
> > > 
> > > in any case, more patches are coming ;-)
> > 
> > Ok, these two are now queued up, feel free to send the rest when you
> > have them ready.
> 
> hi,
> as for 5.10 changes, I have them ready, pushed in here:
>   git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git pahole_fix_5_10
> 
> but it looks like CONFIG_DEBUG_INFO_BTF is not being used in 5.10,
> because I had to backport other similar option, that would break
> the build even earlier (--skip_encoding_btf_vars), or people use
> just old pahole ;-)
> 
> I suggest we wait with this change until somebody actually wants
> this fixed, AFAICS there's no report of broken 5.10 build yet

Consider this your first report :)

My build containers include the latest pahole, as I have noticed more
issues with older pahole in newer kernels than newer pahole in older
kernels, as least until now. I have tripped over this issue on both 5.19
and 5.10, as the stable-only commit b775fbf532dc ("kbuild: Add
skip_encoding_btf_enum64 option to pahole") was only applied to 5.15,
even though it is needed in all kernels prior to 6.0.

Please consider explicitly sending the 5.10 series to stable and
requesting b775fbf532dc to be applied to 5.19.

Cheers,
Nathan