Re: [linux-next:master 10159/12060] arch/arm64/include/asm/pgtable.h:1102:16: error: implicit declaration of function 'pud_valid'; did you mean 'pmd_valid'?

[Will Deacon <will@kernel.org>]

Hey Ryan,

On Wed, May 08, 2024 at 04:38:01PM +0100, Ryan Roberts wrote:
> On 08/05/2024 15:24, kernel test robot wrote:
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> > head:   e7b4ef8fffaca247809337bb78daceb406659f2d
> > commit: f0f5863a0fb0fb48a5881c3f6acca1958899dd76 [10159/12060] arm64/mm: Remove PTE_PROT_NONE bit
> > config: arm64-randconfig-r013-20230528 (https://download.01.org/0day-ci/archive/20240508/202405082221.43rfWxz5-lkp@intel.com/config)
> > compiler: aarch64-linux-gcc (GCC) 13.2.0
> > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240508/202405082221.43rfWxz5-lkp@intel.com/reproduce)
> > 
> > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > the same patch/commit), kindly add following tags
> > | Reported-by: kernel test robot <lkp@intel.com>
> > | Closes: https://lore.kernel.org/oe-kbuild-all/202405082221.43rfWxz5-lkp@intel.com/
> > 
> > All errors (new ones prefixed by >>):
> > 
> >    In file included from include/linux/pgtable.h:6,
> >                     from arch/arm64/include/asm/io.h:12,
> >                     from include/linux/io.h:13,
> >                     from include/linux/irq.h:20,
> >                     from include/asm-generic/hardirq.h:17,
> >                     from arch/arm64/include/asm/hardirq.h:17,
> >                     from include/linux/hardirq.h:11,
> >                     from include/linux/interrupt.h:11,
> >                     from include/linux/trace_recursion.h:5,
> >                     from include/linux/ftrace.h:10,
> >                     from arch/arm64/kernel/asm-offsets.c:12:
> >    arch/arm64/include/asm/pgtable.h: In function 'pud_user_accessible_page':
> >>> arch/arm64/include/asm/pgtable.h:1102:16: error: implicit declaration of function 'pud_valid'; did you mean 'pmd_valid'? [-Werror=implicit-function-declaration]
> >     1102 |         return pud_valid(pud) && !pud_table(pud) && (pud_user(pud) || pud_user_exec(pud));
> >          |                ^~~~~~~~~
> >          |                pmd_valid
> 
> Hi Will,
> 
> Looks like this is due to pud_valid() not being defined for
> CONFIG_PGTABLE_LEVELS <= 2. Seems to me that this is the cleanest solution. But
> pgtable folding breaks my brain so perhaps there is a better way?

I think your approach is the right idea. pgtable-nopmd.h defines
pud_present() as 'return 1', but I think pud_valid() can be false given
that it's only used directly by the arch code.

> What's the process here? Can you just merge this into the broken patch, or do I
> need to re-post the series, or post a fix patch formally?

for-next/mm is stable, so please just submit proper patches on top of
that (and you can add a Fixes: tag as well).

Cheers,

Will