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From:   Ming Lei <tom.leiming@gmail.com>
Date:   Mon, 9 Nov 2020 17:57:37 +0800
Message-ID: <CACVXFVNmYoh20atwG9DOE-ZXFMLqNgGucREBsWAEYnDV4eLs1Q@mail.gmail.com>
Subject: Re: 5.10 tree fails to build
To:     Amy Parker <enbyamy@gmail.com>
Cc:     linux-kbuild@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        masahiroy@kernel.org, michal.lkml@markovi.net,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Jiri Olsa <jolsa@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>
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On Thu, Nov 5, 2020 at 12:58 PM Amy Parker <enbyamy@gmail.com> wrote:
>
> On all attempts to build the 5.10 tree (from either release candidate,
> Linus's tree, Greg's tree, etc), the build crashes on the BTFID vmlinux
> stage. I've tested this on several different devices with completely
> different hardware and kernel configs. The symbol for vfs_getattr
> appears to be missing. Compiles for all of these work on any compile
> on any 5.9 tree. I've tested all 4 5.9 dot-releases as well as the first
> two and last two release candidates and Greg's staging tree.
>
> The specific error is:
>   BTFIDS  vmlinux
> FAILED unresolved symbol vfs_getattr
> make: *** [Makefile:1164: vmlinux] Error 255
>
> Any thoughts as to what's causing this? The main machine I'm
> compiling with is running kernel 5.8.17 with dwarves 1.17. My
> kernel config is attached as `kernel_config`.

Turns out the issue is introduced in the following commit:

commit 6e22ab9da79343532cd3cde39df25e5a5478c692
Author: Jiri Olsa <jolsa@kernel.org>
Date:   Tue Aug 25 21:21:20 2020 +0200

    bpf: Add d_path helper

The issue can be observed reliably when building kernel in Fedora 33 with
F33's kernel config.

GCC: gcc version 10.2.1 20200826 (Red Hat 10.2.1-3) (GCC)

-- 
Ming Lei