powerpc/mm/book(e)(3s)/64: Add page table accounting

Introduce a helper pgtable_gfp_flags() which
just returns the current gfp flags and adds
__GFP_ACCOUNT to account for page table allocation.
The generic helper is added to include/asm/pgalloc.h
and has two variants - WARNING ugly bits ahead

1. If the header is included from a module, no check
for mm == &init_mm is done, since init_mm is not
exported
2. For kernel includes, the check is done and required
see (3e79ec7 arch: x86: charge page tables to kmemcg)

The fundamental assumption is that no module should be
doing pgd/pud/pmd and pte alloc's on behalf of init_mm
directly.

NOTE: This adds an overhead to pmd/pud/pgd allocations
similar to x86.  The other alternative was to implement
pmd_alloc_kernel/pud_alloc_kernel and pgd_alloc_kernel
with their offset variants.

For 4k page size, pte_alloc_one no longer calls
pte_alloc_one_kernel.

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 14 insertions, 6 deletions

diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
index db93cf747a03..8d2d6742a465 100644
--- a/arch/powerpc/mm/pgtable_64.c
+++ b/arch/powerpc/mm/pgtable_64.c
@@ -351,12 +351,20 @@ static pte_t *get_from_cache(struct mm_struct *mm)
 static pte_t *__alloc_for_cache(struct mm_struct *mm, int kernel)
 {
 	void *ret = NULL;
-	struct page *page = alloc_page(GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO);
-	if (!page)
-		return NULL;
-	if (!kernel && !pgtable_page_ctor(page)) {
-		__free_page(page);
-		return NULL;
+	struct page *page;
+
+	if (!kernel) {
+		page = alloc_page(PGALLOC_GFP | __GFP_ACCOUNT);
+		if (!page)
+			return NULL;
+		if (!pgtable_page_ctor(page)) {
+			__free_page(page);
+			return NULL;
+		}
+	} else {
+		page = alloc_page(PGALLOC_GFP);
+		if (!page)
+			return NULL;
 	}
 
 	ret = page_address(page);