On Sun, Feb 06, 2022 at 11:33:40PM +0200, Mike Rapoport wrote:
> On Sun, Feb 06, 2022 at 08:46:45PM +0000, Matthew Wilcox wrote:
> > On Sun, Feb 06, 2022 at 08:13:11PM +0200, Mike Rapoport wrote:
> > > On Fri, Feb 04, 2022 at 07:58:18PM +0000, Matthew Wilcox (Oracle) wrote:
> > > > I need to use this function in common code, so define it for hexagon.
> > > >
> > > > Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> > > > ---
> > > > arch/hexagon/include/asm/pgtable.h | 3 ++-
> > >
> > > Why hexagon out of all architectures?
> > > What about m68k, nios2, nds32 etc?
>
> > Presumably they don't support CONFIG_TRANSPARENT_HUGEPAGE.
> > This code isn't compiled when THP are disabled; at least I haven't
> > had a buildbot complaint for any other architectures.
>
> m68k defconfig fails:
>
> CC mm/page_vma_mapped.o
> mm/page_vma_mapped.c: In function 'page_vma_mapped_walk':
> mm/page_vma_mapped.c:219:20: error: implicit declaration of function 'pmd_pfn'; did you mean 'pmd_off'? [-Werror=implicit-function-declaration]
> 219 | if (!check_pmd(pmd_pfn(pmde), pvmw))
> | ^~~~~~~
> | pmd_off
Ok, so this whole thing is protected by "if (pmd_trans_huge(pmd))"
which is defined to be 0 if !THP. But obviously, gcc is trying to parse
it. So I think we need something like:
#ifndef CONFIG_TRANSPARENT_HUGEPAGE
static inline unsigned long pmd_pfn(pmd_t pmd)
{
BUG();
return 0UL;
}
#endif
but that can have its own problem if architectures define pmd_pfn()
when they don't have CONFIG_TRANSPARENT_HUGEPAGE. Which of course, they
can do.
