Where is PageHead defined in v5.0?

[Tobin C. Harding]

Hi,

I cannot locate the definition of PageHead?  It seems to have
disappeared after v4.0?  I can see it defined as a function here:

	https://elixir.bootlin.com/linux/v4.0/source/include/linux/page-flags.h#L401

But on the mainline (v5.1-rc2) I get:

$ git grep ' PageHead'
include/linux/page-flags.h:int PageHeadHuge(struct page *page);
include/linux/page-flags.h:	return PageHead(page);
include/linux/page-flags.h:	return PageHead(page) && test_bit(PG_double_map, &page[1].flags);
mm/hugetlb.c:	return PageHead(page) && PagePrivate(&page[1]);
mm/hugetlb.c: * PageHeadHuge() only returns true for hugetlbfs head page, but not for
mm/hugetlb.c:int PageHeadHuge(struct page *page_head)

Clearly it is defined _somewhere_.   Anyone any idea what brain
dysfunction I am having right now?

thanks,
Tobin.