arm64 build failures in -next

On Mon, Oct 20, 2014 at 06:12:48AM +0100, Build bot for Mark Brown wrote:

For the past few days arm64 has been failing to build in -next due to:

arm64-allmodconfig ../mm/gup.c:963:3: error: implicit declaration of function 'pgd_huge' [-Werror=implicit-function-declaration]

arm64-defconfig ../mm/gup.c:963:3: error: implicit declaration of function 'pgd_huge' [-Werror=implicit-function-declaration]

which appears to be due to "mm/gup.c: update generic gup implementation to handle hugepage directory". That patch added a default definition of pgd_huge() in the !CONFIG_HUGETLB_PAGE case but only PowerPC provides an actual definition of that function.