Re: linux-next failing build due to missing cubictcp_state symbol

From: Jiri Slaby <jirislaby@kernel.org>
To: "Michal Suchánek" <msuchanek@suse.de>, "Jiri Olsa" <jolsa@redhat.com>
Cc: Yonghong Song <yhs@fb.com>,
	linux-kernel@vger.kernel.org, Martin KaFai Lau <kafai@fb.com>,
	"David S. Miller" <davem@davemloft.net>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	David Ahern <dsahern@kernel.org>,
	Jakub Kicinski <kuba@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Song Liu <songliubraving@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	netdev@vger.kernel.org, bpf@vger.kernel.org,
	Jiri Olsa <jolsa@kernel.org>,
	Jesper Dangaard Brouer <brouer@redhat.com>
Subject: Re: linux-next failing build due to missing cubictcp_state symbol
Date: Mon, 3 May 2021 08:11:50 +0200	[thread overview]
Message-ID: <6c14f3c8-7474-9f3f-b4a6-2966cb19e1ed@kernel.org> (raw)
In-Reply-To: <3d148516-0472-8f0a-085b-94d68c5cc0d5@suse.com>

On 01. 05. 21, 8:45, 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).

It's not that bogus. I forgot an asterisk:
> #0  find_function (btfe=0x100269f80, name=0x10024631c "stream_open") at /usr/src/debug/dwarves-1.21-1.1.ppc64/btf_encoder.c:350
> (gdb) p (*functions)@84
> $5 = {{name = 0x7ffff68e0922 ".__se_compat_sys_ftruncate", addr = 75232, size = 72, sh_addr = 65536, generated = false}, {
>     name = 0x7ffff68e019e ".__se_compat_sys_open", addr = 80592, size = 216, sh_addr = 65536, generated = false}, {
>     name = 0x7ffff68e0076 ".__se_compat_sys_openat", addr = 80816, size = 232, sh_addr = 65536, generated = false}, {
>     name = 0x7ffff68e0908 ".__se_compat_sys_truncate", addr = 74304, size = 100, sh_addr = 65536, generated = false}, {
...
>     name = 0x7ffff68e0808 ".stream_open", addr = 65824, size = 72, sh_addr = 65536, generated = false}, {
...
>     name = 0x7ffff68e0751 ".vfs_truncate", addr = 73392, size = 544, sh_addr = 65536, generated = false}}

The dot makes the difference, of course. The question is why is it 
there? I keep looking into it. Only if someone has an immediate idea...

thanks,
-- 
js
suse labs