[vfs:for-linus 1/8] arch/x86/built-in.o:undefined reference to `compat_sys_io_setup'

[vfs:for-linus 1/8] arch/x86/built-in.o:undefined reference to `compat_sys_io_setup'

[kbuild test robot]

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git for-linus
head:   d0375bfcdd0de588d9f8ee7ac9d2bc93c333e4fe
commit: e46c3fc8ff9e7aa152ef078af7067d5391f4fe18 [1/8] move aio compat to fs/aio.c
config: x86_64-randconfig-s2-12230841 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        git checkout e46c3fc8ff9e7aa152ef078af7067d5391f4fe18
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

>> arch/x86/built-in.o:(.rodata+0x10f8): undefined reference to `compat_sys_io_setup'
>> arch/x86/built-in.o:(.rodata+0x1100): undefined reference to `compat_sys_io_submit'
   arch/x86/built-in.o:(.rodata+0x1b48): undefined reference to `compat_sys_io_setup'
>> arch/x86/built-in.o:(.rodata+0x1b58): undefined reference to `compat_sys_io_getevents'
   arch/x86/built-in.o:(.rodata+0x1b60): undefined reference to `compat_sys_io_submit'

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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Re: [vfs:for-linus 1/8] arch/x86/built-in.o:undefined reference to `compat_sys_io_setup'

[Al Viro]

On Fri, Dec 23, 2016 at 11:25:22AM +0800, kbuild test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git for-linus
> head:   d0375bfcdd0de588d9f8ee7ac9d2bc93c333e4fe
> commit: e46c3fc8ff9e7aa152ef078af7067d5391f4fe18 [1/8] move aio compat to fs/aio.c
> config: x86_64-randconfig-s2-12230841 (attached as .config)
> compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
> reproduce:
>         git checkout e46c3fc8ff9e7aa152ef078af7067d5391f4fe18
>         # save the attached .config to linux build tree
>         make ARCH=x86_64 

What the...?  Wait a sec, you have CONFIG_COMPAT, but not CONFIG_AIO in
there?  What's missing there is
+cond_syscall(compat_sys_io_setup);
+cond_syscall(compat_sys_io_submit);
+cond_syscall(compat_sys_io_getevents);
in kernel/sys_ni.c

Lovely, that - previously mainline had built compat_sys_io_setup() et.al. on
configs without CONFIG_AIO, only to have it allocate a native iocb array,
carefully convert the 32bit ones into it, then call dummy do_io_submit()
which did nothing and returned 0.  While 64bit task doing the same would
get -ENOSYS instead...  Fixed and folded.

My apologies - I hadn't checked that config and missed that weirdness
completely.