[PATCH V13] mm/debug: Add tests validating architecture page table helpers

[Andrew Morton]

On Thu, 6 Feb 2020 13:49:35 +0530 Anshuman Khandual <anshuman.khandual at arm.com> wrote:

> 
> On 02/06/2020 04:40 AM, kbuild test robot wrote:
> > Hi Anshuman,
> > 
> > Thank you for the patch! Yet something to improve:
> > 
> > [auto build test ERROR on powerpc/next]
> > [also build test ERROR on s390/features linus/master arc/for-next v5.5]
> > [cannot apply to mmotm/master tip/x86/core arm64/for-next/core next-20200205]
> > [if your patch is applied to the wrong git tree, please drop us a note to help
> > improve the system. BTW, we also suggest to use '--base' option to specify the
> > base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
> > 
> > url:    https://github.com/0day-ci/linux/commits/Anshuman-Khandual/mm-debug-Add-tests-validating-architecture-page-table-helpers/20200205-215507
> > base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
> > config: ia64-allmodconfig (attached as .config)
> > compiler: ia64-linux-gcc (GCC) 7.5.0
> > reproduce:
> >         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> >         chmod +x ~/bin/make.cross
> >         # save the attached .config to linux build tree
> >         GCC_VERSION=7.5.0 make.cross ARCH=ia64 
> > 
> > If you fix the issue, kindly add following tag
> > Reported-by: kbuild test robot <lkp at intel.com>
> > 
> > All error/warnings (new ones prefixed by >>):
> > 
> >    In file included from include/asm-generic/pgtable-nopud.h:8:0,
> >                     from arch/ia64/include/asm/pgtable.h:586,
> >                     from include/linux/mm.h:99,
> >                     from include/linux/highmem.h:8,
> >                     from mm/debug_vm_pgtable.c:14:
> >    mm/debug_vm_pgtable.c: In function 'pud_clear_tests':
> >>> include/asm-generic/pgtable-nop4d-hack.h:47:32: error: implicit declaration of function '__pgd'; did you mean '__p4d'? [-Werror=implicit-function-declaration]
> >     #define __pud(x)    ((pud_t) { __pgd(x) })
> >                                    ^
> >>> mm/debug_vm_pgtable.c:141:8: note: in expansion of macro '__pud'
> >      pud = __pud(pud_val(pud) | RANDOM_ORVALUE);
> >            ^~~~~
> >>> include/asm-generic/pgtable-nop4d-hack.h:47:22: warning: missing braces around initializer [-Wmissing-braces]
> >     #define __pud(x)    ((pud_t) { __pgd(x) })
> >                          ^
> >>> mm/debug_vm_pgtable.c:141:8: note: in expansion of macro '__pud'
> >      pud = __pud(pud_val(pud) | RANDOM_ORVALUE);
> >            ^~~~~
> >    cc1: some warnings being treated as errors
> 
> This build failure is expected now given that we have allowed DEBUG_VM_PGTABLE
> with EXPERT without platform requiring ARCH_HAS_DEBUG_VM_PGTABLE. This problem
> i.e build failure caused without a platform __pgd(), is known to exist both on
> ia64 and arm (32bit) platforms. Please refer https://lkml.org/lkml/2019/9/24/314
> for details where this was discussed earlier.
> 

I'd prefer not to merge a patch which is known to cause build
regressions.  Is there some temporary thing we can do to prevent these
errors until arch maintainers(?) get around to implementing the
long-term fixes?