[PATCH v3 4/6] powerpc/mm: Add devmap support for ppc64

[Oliver]

On Tue, Jun 27, 2017 at 12:33 PM, Michael Ellerman <mpe at ellerman.id.au> wrote:
> kbuild test robot <lkp at intel.com> writes:
>
>> Hi Oliver,
>>
>> [auto build test ERROR on powerpc/next]
>> [also build test ERROR on v4.12-rc6 next-20170623]
>> [if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
>>
>> url:    https://github.com/0day-ci/linux/commits/Oliver-O-Halloran/mm-x86-Add-ARCH_HAS_ZONE_DEVICE-to-Kconfig/20170625-102522
>> base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
>> config: powerpc-defconfig (attached as .config)
>> compiler: powerpc64-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
>> reproduce:
>>         wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>>         chmod +x ~/bin/make.cross
>>         # save the attached .config to linux build tree
>>         make.cross ARCH=powerpc
>>
>> All errors (new ones prefixed by >>):
>>
>>    mm/gup.c: In function '__gup_device_huge_pud':
>>>> mm/gup.c:1329:14: error: implicit declaration of function 'pud_pfn' [-Werror=implicit-function-declaration]
>>      fault_pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
>>                  ^~~~~~~
>>    cc1: some warnings being treated as errors
>
> The key here is that CONFIG_TRANSPARENT_HUGEPAGE=n.
>
> So this needs to be fixed before I can merge this.
>
> I think the problem is just that pud_pfn() is inside #ifdef
> CONFIG_TRANSPARENT_HUGEPAGE but shouldn't be.

I'm not 100% sold on making pud_pfn() independent of THP. pmd_pfn() is
used a few times in generic code, but the usages are always gated by a
#ifdef CONFIG_TRANSPARENT_HUGEPAGE so I think we should be doing the
same here. I sent a patch[1] yesterday to fix the usage in gup.c, but
I'll do a respin if you want.

Thanks,
Oliver

[1] http://marc.info/?l=linux-mm&m=149845912612363&w=4