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

[Qu Wenruo]

在 2025/11/17 13:33, Qu Wenruo 写道:
> 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.

Furthermore, if just compiling on old kernels (in my case, 6.17.8), I 
haven't yet hit a linking time segfault.

So it's something in the v6.18 release cycle.

Not sure if it's the recent Zen5 related hassles.

Thanks,
Qu

> > - 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