Re: [PATCH -next 1/7] mm_types: add _last_cpupid into folio

[Kefeng Wang]

On 2023/10/10 16:17, Huang, Ying wrote:
> Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> writes:
>
> > At present, only arc/sparc/m68k define WANT_PAGE_VIRTUAL, both of
> > them don't support numa balancing, and the page struct is aligned
> > to _struct_page_alignment, it is safe to move _last_cpupid before
> > 'virtual' in page, meanwhile, add it into folio, which make us to
> > use folio->_last_cpupid directly.
>
> Add BUILD_BUG_ON() to check this automatically?

The WANT_PAGE_VIRTUAL and LAST_CPUPID_NOT_IN_PAGE_FLAGS are not
conflict, the check is to make sure that the re-order the virtual
and _last_cpupid is minimal impact, and there is a build warning in
mm/memory.c when the LAST_CPUPID_NOT_IN_PAGE_FLAGS is enabled, so I
don't think we need a new BUILD_BUG_ON here.

Thanks.

> --
> Best Regards,
> Huang, Ying