Re: [mmotm:master 124/234] mm/vmalloc.c:520:6: error: implicit declaration of function 'p4d_large'; did you mean 'p4d_page'?

[Nicholas Piggin <npiggin@gmail.com>]

kbuild test robot's on May 31, 2019 9:42 am:
> tree:   git://git.cmpxchg.org/linux-mmotm.git master
> head:   6f11685c34f638e200dd9e821491584ef5717d57
> commit: 91c106f5d623b94305af3fd91113de1cba768d73 [124/234] mm/vmalloc: hugepage vmalloc mappings
> config: arm64-allyesconfig (attached as .config)
> compiler: aarch64-linux-gcc (GCC) 7.4.0
> reproduce:
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         git checkout 91c106f5d623b94305af3fd91113de1cba768d73
>         # save the attached .config to linux build tree
>         GCC_VERSION=7.4.0 make.cross ARCH=arm64 
> 
> If you fix the issue, kindly add following tag
> Reported-by: kbuild test robot <lkp@intel.com>
> 
> All errors (new ones prefixed by >>):
> 
>    mm/vmalloc.c: In function 'vmap_range':
>    mm/vmalloc.c:325:19: error: 'start' undeclared (first use in this function); did you mean 'stat'?
>      flush_cache_vmap(start, end);
>                       ^~~~~
>                       stat
>    mm/vmalloc.c:325:19: note: each undeclared identifier is reported only once for each function it appears in
>    mm/vmalloc.c: In function 'vmalloc_to_page':
>>> mm/vmalloc.c:520:6: error: implicit declaration of function 'p4d_large'; did you mean 'p4d_page'? [-Werror=implicit-function-declaration]
>      if (p4d_large(*p4d))
>          ^~~~~~~~~
>          p4d_page

Hmm, okay p?d_large I guess is not quite the right thing to use here. It
almost is, but it's tied to userspace/thp options.

What would people prefer to do here? We could have architectures that
define HAVE_ARCH_HUGE_VMAP to also provide p?d_huge_kernel() tests for
their kernel page tables?

Thanks,
Nick