Re: [BUG] fuse/virtiofs: kernel module build fail

[Luis Henriques <luis@igalia.com>]

On Thu, Jun 12 2025, Joanne Koong wrote:

> On Thu, Jun 12, 2025 at 4:19 AM Brian Foster <bfoster@redhat.com> wrote:
>>
>> Hi folks,
>>
>> I run kernel compiles quite a bit over virtiofs in some of my local test
>> setups and recently ran into an issue building xfs.ko once I had a
>> v6.16-rc kernel installed in my guest. The test case is a simple:
>>
>>   make -j N M=fs/xfs clean; make -j N M=fs/xfs
>
> Hi Brian,
>
> If I'm understanding your setup correctly, basically you have the
> v6.16-rc kernel running on a VM, on that VM you mounted a virtiofs
> directory that references a linux repo that's on your host OS, and
> then from your VM you are compiling the fs/xfs module in that shared
> linux repo?
>
> I tried this on my local setup but I'm seeing some other issues:
>
> make[1]: Entering directory '/home/vmuser/linux/linux/fs/xfs'
>   LD [M]  xfs.o
> xfs.o: warning: objtool: __traceiter_xfs_attr_list_sf+0x23:
> unannotated intra-function call
> make[3]: *** [/home/vmuser/linux/linux/scripts/Makefile.build:501:
> xfs.o] Error 255
> make[3]: *** Deleting file 'xfs.o'
> make[2]: *** [/home/vmuser/linux/linux/Makefile:2006: .] Error 2
> make[1]: *** [/home/vmuser/linux/linux/Makefile:248: __sub-make] Error 2
> make[1]: Leaving directory '/home/vmuser/linux/linux/fs/xfs'
> make: *** [Makefile:248: __sub-make] Error 2
>
> Did you also run into these issues when you were compiling?

This is probably just a shot in the dark, but I remember seeing similar
build failures long time ago due to virtiofs caching.  I don't remember
the details, but maybe it's worth checking that.  I *think* that what
fixed it for me was to use '--cache auto'.

Cheers,
-- 
Luís


> Taking a look at what 63c69ad3d18a ("fuse: refactor
> fuse_fill_write_pages()") does, it seems odd to me that the changes in
> that commit would lead to the issues you're seeing - that commit
> doesn't alter structs or memory layouts in any way. I'll keep trying
> to repro the issue you're seeing.
>
>>
>> ... and ends up spitting out link time errors like this as of commit
>> 63c69ad3d18a ("fuse: refactor fuse_fill_write_pages()"):
>>
>> ...
>>   CC [M]  xfs.mod.o
>>   CC [M]  .module-common.o
>>   LD [M]  xfs.ko
>>   BTF [M] xfs.ko
>> die__process: DW_TAG_compile_unit, DW_TAG_type_unit, DW_TAG_partial_unit or DW_TAG_skeleton_unit expected got subprogram (0x2e) @ ed957!
>> error decoding cu i_mmap_rwsem
>> error decoding cu
>> ...
>> error decoding cu
>> pahole: xfs.ko: Invalid argument
>> make[3]: *** [/root/repos/linux/scripts/Makefile.modfinal:57: xfs.ko] Error 1
>> make[3]: *** Deleting file 'xfs.ko'
>> make[2]: *** [/root/repos/linux/Makefile:1937: modules] Error 2
>> make[1]: *** [/root/repos/linux/Makefile:248: __sub-make] Error 2
>> make[1]: Leaving directory '/root/repos/linux/fs/xfs'
>> make: *** [Makefile:248: __sub-make] Error 2
>>
>> ... or this on latest master:
>>
>> ...
>>   LD [M]  fs/xfs/xfs.o
>> fs/xfs/xfs.o: error: objtool: can't find reloc entry symbol 2145964924 for .rela.text
>> make[4]: *** [scripts/Makefile.build:501: fs/xfs/xfs.o] Error 1
>> make[4]: *** Deleting file 'fs/xfs/xfs.o'
>> make[3]: *** [scripts/Makefile.build:554: fs/xfs] Error 2
>> make[2]: *** [scripts/Makefile.build:554: fs] Error 2
>> make[1]: *** [/root/repos/linux/Makefile:2006: .] Error 2
>> make: *** [Makefile:248: __sub-make] Error 2
>>
>> The latter failure is what I saw through most of a bisect so I suspect
>> one of the related followon commits alters the failure characteristic
>> from the former, but I've not confirmed that. Also note out of
>> convenience my test was to just recompile xfs.ko out of the same tree I
>> was bisecting from because the failures were consistent and seemed to be
>> a runtime kernel issue and not a source tree issue.
>>
>> I haven't had a chance to dig any further than this (and JFYI I'm
>> probably not going to be responsive through the rest of today). I just
>> completed the bisect and wanted to get it on list sooner rather than
>> later..
>>
>> Brian
>>
>