linux-kernel - Re: linux-next failing build due to missing cubictcp

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Message-ID: <20210501105400.GG6564@kitsune.suse.cz>
Date:   Sat, 1 May 2021 12:54:00 +0200
From:   Michal Suchánek <msuchanek@...e.de>
To:     Jiri Slaby <jslaby@...e.com>
Cc:     Jiri Olsa <jolsa@...hat.com>, Yonghong Song <yhs@...com>,
        linux-kernel@...r.kernel.org, Martin KaFai Lau <kafai@...com>,
        "David S. Miller" <davem@...emloft.net>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Song Liu <songliubraving@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, Jiri Olsa <jolsa@...nel.org>,
        Jesper Dangaard Brouer <brouer@...hat.com>
Subject: Re: linux-next failing build due to missing cubictcp_state symbol

On Sat, May 01, 2021 at 08:45:50AM +0200, Jiri Slaby wrote:
> On 30. 04. 21, 19:47, Michal Suchánek wrote:
> > CC another Jiri
> > 
> > On Tue, Apr 27, 2021 at 02:12:37PM +0200, Michal Suchánek wrote:
> > > On Mon, Apr 26, 2021 at 09:16:36PM +0200, Jiri Olsa wrote:
> > > > On Mon, Apr 26, 2021 at 06:03:19PM +0200, Jiri Olsa wrote:
> > > > > On Mon, Apr 26, 2021 at 08:41:49AM -0700, Yonghong Song wrote:
> > > > > > 
> > > > > > 
> > > > > > On 4/26/21 5:14 AM, Michal Suchánek wrote:
> > > > > > > On Mon, Apr 26, 2021 at 02:12:20PM +0200, Michal Suchánek wrote:
> > > > > > > > On Mon, Apr 26, 2021 at 01:32:15PM +0200, Michal Suchánek wrote:
> > > > > > > > > On Sun, Apr 25, 2021 at 01:15:45PM +0200, Michal Suchánek wrote:
> > > > > > > > > > On Fri, Apr 23, 2021 at 07:55:28PM +0200, Michal Suchánek wrote:
> > > > > > > > > > > On Fri, Apr 23, 2021 at 07:41:29AM -0700, Yonghong Song wrote:
> > > > > > > > > > > > 
> > > > > > > > > > > > 
> > > > > > > > > > > > On 4/23/21 6:05 AM, Michal Suchánek wrote:
> > > > > > > > > > > > > Hello,
> > > > > > > > > > > > > 
> > > > > > > > > > > > > I see this build error in linux-next (config attached).
> > > > > > > > > > > > > 
> > > > > > > > > > > > > [ 4939s]   LD      vmlinux
> > > > > > > > > > > > > [ 4959s]   BTFIDS  vmlinux
> > > > > > > > > > > > > [ 4959s] FAILED unresolved symbol cubictcp_state
> > > > > > > > > > > > > [ 4960s] make[1]: ***
> > > > > > > > > > > > > [/home/abuild/rpmbuild/BUILD/kernel-vanilla-5.12~rc8.next.20210422/linux-5.12-rc8-next-20210422/Makefile:1277:
> > > > > > > > > > > > > vmlinux] Error 255
> > > > > > > > > > > > > [ 4960s] make: *** [../Makefile:222: __sub-make] Error 2
> > > > > 
> > > > > this one was reported by Jesper and was fixed by upgrading pahole
> > > > > that contains the new function generation fixes (v1.19)
> > > > > 
> > > > > > > > > > > > 
> > > > > > > > > > > > Looks like you have DYNAMIC_FTRACE config option enabled already.
> > > > > > > > > > > > Could you try a later version of pahole?
> > > > > > > > > > > 
> > > > > > > > > > > Is this requireent new?
> > > > > > > > > > > 
> > > > > > > > > > > I have pahole 1.20, and master does build without problems.
> > > > > > > > > > > 
> > > > > > > > > > > If newer version is needed can a check be added?
> > > > > > > > > > 
> > > > > > > > > > With dwarves 1.21 some architectures are fixed and some report other
> > > > > > > > > > missing symbol. Definitely an improvenent.
> > > > > > > > > > 
> > > > > > > > > > I see some new type support was added so it makes sense if that type is
> > > > > > > > > > used the new dwarves are needed.
> > > > > > > > > 
> > > > > > > > > Ok, here is the current failure with dwarves 1.21 on 5.12:
> > > > > > > > > 
> > > > > > > > > [ 2548s]   LD      vmlinux
> > > > > > > > > [ 2557s]   BTFIDS  vmlinux
> > > > > > > > > [ 2557s] FAILED unresolved symbol vfs_truncate
> > > > > > > > > [ 2558s] make[1]: ***
> > > > > > > > > [/home/abuild/rpmbuild/BUILD/kernel-kvmsmall-5.12.0/linux-5.12/Makefile:1213:
> > > > > > > > > vmlinux] Error 255
> > > > > > 
> > > > > > This is PPC64, from attached config:
> > > > > >    CONFIG_PPC64=y
> > > > > > I don't have environment to cross-compile for PPC64.
> > > > > > Jiri, could you take a look? Thanks!
> > > > > 
> > > > > looks like vfs_truncate did not get into BTF data,
> > > > > I'll try to reproduce
> 
> _None_ of the functions are generated by pahole -J from debuginfo on ppc64.
> debuginfo appears to be correct. Neither pahole -J fs/open.o works
> correctly. collect_functions in dwarves seems to be defunct on ppc64...
> "functions" array is bogus (so find_function -- the bsearch -- fails). I
> didn't have more time to continue debugging. This is where I stopped.

A workaround is to apply
https://lore.kernel.org/linuxppc-dev/20200428112517.1402927-1-npiggin@gmail.com/
and build as ABI v2

Thanks

Michal