Re: Objtool segfault inside an VM, based on commit 24172e0d7990

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

在 2025/11/17 13:10, Qu Wenruo 写道:
> Hi,
> 
> Recently I'm hitting pretty frequent objtool crashes, sometimes during 
> module linking (btrfs in my case) sometimes during the vmlinux linking.
> 
> Unfortunately I don't have a coredump for it.
> 
> The only info so far is from dmesg (and obvious the compile failure):
> 
> [  625.066787] traps: objtool[46220] general protection fault 
> ip:563ab54c6eb0 sp:7ffd9c2ba7c8 error:0 in 
> objtool[19eb0,563ab54b2000+1f000]
> 
> The involved VM has the following spec:
> 
> - Kernel branch
>    Btrfs' development branch.
> 
>    The base commit is 24172e0d79900908cf5ebf366600616d29c9b417, around
>    v6.18-rc6.
> 
> - 10 vCPU, host CPU features pass-through, x86_64
>    Host is using AMD HX370.
> 
>    Haven't yet hit the segfault on aarch64.
> 
> - 8G vRAM
>    Thus it should be enough for most cases.
> 
> - Toolchain versions:
>    gcc 15.2.1+r301+gf24307422d1d-1
>    binutils 2.45.1-1
> 
>    All from the latest Archlinux.
> 
>    Older gcc (15.2.1+r22+gc4e96a094636-1) and binutils 
> (2.45+r29+g2b2e51a31ec7-1) are causing the same segfault.
> 
>    Haven't yet tried LLVM.

Unfortunately LLVM is hitting the same crash.
I'm using llvm/clang/lld 21.1.5.

So it doesn't look like a toolchain specific bug, but something specific 
to objtool of the kernel.


Thanks,
Qu

> 
> - Kernel config
>    Attached.
> 
>    Sometimes tweaking the config can workaround the bug a little,
>    but not reliably.
> 
> Is this a known problem and can I work around the segfault?
> 
> Thanks,
> Qu