[PATCH V2] mm: Introduce GFP_PGTABLE

[Anshuman Khandual <anshuman.khandual@arm.com>]

All architectures have been defining their own PGALLOC_GFP as (GFP_KERNEL |
__GFP_ZERO) and using it for allocating page table pages. This causes some
code duplication which can be easily avoided. GFP_KERNEL allocated and
cleared out pages (__GFP_ZERO) are required for page tables on any given
architecture. This creates a new generic GFP flag flag which can be used
for any page table page allocation. Does not cause any functional change.

GFP_PGTABLE is being added into include/asm-generic/pgtable.h which is the
generic page tabe header just to prevent it's potential misuse as a general
allocation flag if included in include/linux/gfp.h.

Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
Build tested on arm, arm64, powerpc, powerpc64le and x86.
Boot tested on arm64 and x86.

Changes in V2:

- Moved GFP_PGTABLE into include/asm-generic/pgtable.h
- On X86 added __GFP_ACCOUNT into GFP_PGTABLE at various places
- Replaced possible flags on riscv and nds32 with GFP_PGTABLE

Original V1: https://lkml.org/lkml/2019/1/12/54 

 arch/arm/include/asm/pgalloc.h               |  8 +++-----
 arch/arm/mm/mmu.c                            |  2 +-
 arch/arm64/include/asm/pgalloc.h             |  9 ++++-----
 arch/arm64/mm/mmu.c                          |  2 +-
 arch/arm64/mm/pgd.c                          |  4 ++--
 arch/nds32/include/asm/pgalloc.h             |  3 +--
 arch/powerpc/include/asm/book3s/64/pgalloc.h |  6 +++---
 arch/powerpc/include/asm/pgalloc.h           |  2 --
 arch/powerpc/kvm/book3s_64_mmu_hv.c          |  2 +-
 arch/powerpc/mm/pgtable-frag.c               |  4 ++--
 arch/riscv/include/asm/pgalloc.h             |  8 +++-----
 arch/sh/mm/pgtable.c                         |  6 ++----
 arch/unicore32/include/asm/pgalloc.h         |  6 ++----
 arch/x86/kernel/espfix_64.c                  |  6 ++----
 arch/x86/mm/pgtable.c                        | 15 +++++++--------
 include/asm-generic/pgtable.h                |  2 ++
 virt/kvm/arm/mmu.c                           |  2 +-
 17 files changed, 37 insertions(+), 50 deletions(-)

diff --git a/arch/arm/include/asm/pgalloc.h b/arch/arm/include/asm/pgalloc.h
index 17ab72f..72be6f5 100644
--- a/arch/arm/include/asm/pgalloc.h
+++ b/arch/arm/include/asm/pgalloc.h
@@ -57,8 +57,6 @@ static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
 extern pgd_t *pgd_alloc(struct mm_struct *mm);
 extern void pgd_free(struct mm_struct *mm, pgd_t *pgd);
 
-#define PGALLOC_GFP	(GFP_KERNEL | __GFP_ZERO)
-
 static inline void clean_pte_table(pte_t *pte)
 {
 	clean_dcache_area(pte + PTE_HWTABLE_PTRS, PTE_HWTABLE_SIZE);
@@ -85,7 +83,7 @@ pte_alloc_one_kernel(struct mm_struct *mm)
 {
 	pte_t *pte;
 
-	pte = (pte_t *)__get_free_page(PGALLOC_GFP);
+	pte = (pte_t *)__get_free_page(GFP_PGTABLE);
 	if (pte)
 		clean_pte_table(pte);
 
@@ -98,9 +96,9 @@ pte_alloc_one(struct mm_struct *mm)
 	struct page *pte;
 
 #ifdef CONFIG_HIGHPTE
-	pte = alloc_pages(PGALLOC_GFP | __GFP_HIGHMEM, 0);
+	pte = alloc_pages(GFP_PGTABLE | __GFP_HIGHMEM, 0);
 #else
-	pte = alloc_pages(PGALLOC_GFP, 0);
+	pte = alloc_pages(GFP_PGTABLE, 0);
 #endif
 	if (!pte)
 		return NULL;
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index f5cc1cc..6d47784 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -733,7 +733,7 @@ static void __init *early_alloc(unsigned long sz)
 
 static void *__init late_alloc(unsigned long sz)
 {
-	void *ptr = (void *)__get_free_pages(PGALLOC_GFP, get_order(sz));
+	void *ptr = (void *)__get_free_pages(GFP_PGTABLE, get_order(sz));
 
 	if (!ptr || !pgtable_page_ctor(virt_to_page(ptr)))
 		BUG();
diff --git a/arch/arm64/include/asm/pgalloc.h b/arch/arm64/include/asm/pgalloc.h
index 52fa47c..d5c75bf 100644
--- a/arch/arm64/include/asm/pgalloc.h
+++ b/arch/arm64/include/asm/pgalloc.h
@@ -26,14 +26,13 @@
 
 #define check_pgt_cache()		do { } while (0)
 
-#define PGALLOC_GFP	(GFP_KERNEL | __GFP_ZERO)
 #define PGD_SIZE	(PTRS_PER_PGD * sizeof(pgd_t))
 
 #if CONFIG_PGTABLE_LEVELS > 2
 
 static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
 {
-	return (pmd_t *)__get_free_page(PGALLOC_GFP);
+	return (pmd_t *)__get_free_page(GFP_PGTABLE);
 }
 
 static inline void pmd_free(struct mm_struct *mm, pmd_t *pmdp)
@@ -62,7 +61,7 @@ static inline void __pud_populate(pud_t *pudp, phys_addr_t pmdp, pudval_t prot)
 
 static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long addr)
 {
-	return (pud_t *)__get_free_page(PGALLOC_GFP);
+	return (pud_t *)__get_free_page(GFP_PGTABLE);
 }
 
 static inline void pud_free(struct mm_struct *mm, pud_t *pudp)
@@ -93,7 +92,7 @@ extern void pgd_free(struct mm_struct *mm, pgd_t *pgdp);
 static inline pte_t *
 pte_alloc_one_kernel(struct mm_struct *mm)
 {
-	return (pte_t *)__get_free_page(PGALLOC_GFP);
+	return (pte_t *)__get_free_page(GFP_PGTABLE);
 }
 
 static inline pgtable_t
@@ -101,7 +100,7 @@ pte_alloc_one(struct mm_struct *mm)
 {
 	struct page *pte;
 
-	pte = alloc_pages(PGALLOC_GFP, 0);
+	pte = alloc_pages(GFP_PGTABLE, 0);
 	if (!pte)
 		return NULL;
 	if (!pgtable_page_ctor(pte)) {
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index b6f5aa5..07b1c0f 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -372,7 +372,7 @@ static void __create_pgd_mapping(pgd_t *pgdir, phys_addr_t phys,
 
 static phys_addr_t pgd_pgtable_alloc(void)
 {
-	void *ptr = (void *)__get_free_page(PGALLOC_GFP);
+	void *ptr = (void *)__get_free_page(GFP_PGTABLE);
 	if (!ptr || !pgtable_page_ctor(virt_to_page(ptr)))
 		BUG();
 
diff --git a/arch/arm64/mm/pgd.c b/arch/arm64/mm/pgd.c
index 289f911..5b28e2b 100644
--- a/arch/arm64/mm/pgd.c
+++ b/arch/arm64/mm/pgd.c
@@ -31,9 +31,9 @@ static struct kmem_cache *pgd_cache __ro_after_init;
 pgd_t *pgd_alloc(struct mm_struct *mm)
 {
 	if (PGD_SIZE = PAGE_SIZE)
-		return (pgd_t *)__get_free_page(PGALLOC_GFP);
+		return (pgd_t *)__get_free_page(GFP_PGTABLE);
 	else
-		return kmem_cache_alloc(pgd_cache, PGALLOC_GFP);
+		return kmem_cache_alloc(pgd_cache, GFP_PGTABLE);
 }
 
 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
diff --git a/arch/nds32/include/asm/pgalloc.h b/arch/nds32/include/asm/pgalloc.h
index 3c5fee5..e1137ce 100644
--- a/arch/nds32/include/asm/pgalloc.h
+++ b/arch/nds32/include/asm/pgalloc.h
@@ -27,8 +27,7 @@ static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
 	pte_t *pte;
 
 	pte -	    (pte_t *) __get_free_page(GFP_KERNEL | __GFP_RETRY_MAYFAIL |
-				      __GFP_ZERO);
+	    (pte_t *) __get_free_page(GFP_PGTABLE | __GFP_RETRY_MAYFAIL);
 
 	return pte;
 }
diff --git a/arch/powerpc/include/asm/book3s/64/pgalloc.h b/arch/powerpc/include/asm/book3s/64/pgalloc.h
index 9c11732..71704e5 100644
--- a/arch/powerpc/include/asm/book3s/64/pgalloc.h
+++ b/arch/powerpc/include/asm/book3s/64/pgalloc.h
@@ -52,11 +52,11 @@ void pte_frag_destroy(void *pte_frag);
 static inline pgd_t *radix__pgd_alloc(struct mm_struct *mm)
 {
 #ifdef CONFIG_PPC_64K_PAGES
-	return (pgd_t *)__get_free_page(pgtable_gfp_flags(mm, PGALLOC_GFP));
+	return (pgd_t *)__get_free_page(pgtable_gfp_flags(mm, GFP_PGTABLE));
 #else
 	struct page *page;
-	page = alloc_pages(pgtable_gfp_flags(mm, PGALLOC_GFP | __GFP_RETRY_MAYFAIL),
-				4);
+	page = alloc_pages(pgtable_gfp_flags(mm, GFP_PGTABLE |
+				__GFP_RETRY_MAYFAIL), 4);
 	if (!page)
 		return NULL;
 	return (pgd_t *) page_address(page);
diff --git a/arch/powerpc/include/asm/pgalloc.h b/arch/powerpc/include/asm/pgalloc.h
index e11f030..3b11e8b 100644
--- a/arch/powerpc/include/asm/pgalloc.h
+++ b/arch/powerpc/include/asm/pgalloc.h
@@ -18,8 +18,6 @@ static inline gfp_t pgtable_gfp_flags(struct mm_struct *mm, gfp_t gfp)
 }
 #endif /* MODULE */
 
-#define PGALLOC_GFP (GFP_KERNEL | __GFP_ZERO)
-
 #ifdef CONFIG_PPC_BOOK3S
 #include <asm/book3s/pgalloc.h>
 #else
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index bd2dcfb..b419878 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -97,7 +97,7 @@ int kvmppc_allocate_hpt(struct kvm_hpt_info *info, u32 order)
 	}
 
 	if (!hpt)
-		hpt = __get_free_pages(GFP_KERNEL|__GFP_ZERO|__GFP_RETRY_MAYFAIL
+		hpt = __get_free_pages(GFP_PGTABLE | __GFP_RETRY_MAYFAIL
 				       |__GFP_NOWARN, order - PAGE_SHIFT);
 
 	if (!hpt)
diff --git a/arch/powerpc/mm/pgtable-frag.c b/arch/powerpc/mm/pgtable-frag.c
index a7b0521..211aaa7 100644
--- a/arch/powerpc/mm/pgtable-frag.c
+++ b/arch/powerpc/mm/pgtable-frag.c
@@ -58,7 +58,7 @@ static pte_t *__alloc_for_ptecache(struct mm_struct *mm, int kernel)
 	struct page *page;
 
 	if (!kernel) {
-		page = alloc_page(PGALLOC_GFP | __GFP_ACCOUNT);
+		page = alloc_page(GFP_PGTABLE | __GFP_ACCOUNT);
 		if (!page)
 			return NULL;
 		if (!pgtable_page_ctor(page)) {
@@ -66,7 +66,7 @@ static pte_t *__alloc_for_ptecache(struct mm_struct *mm, int kernel)
 			return NULL;
 		}
 	} else {
-		page = alloc_page(PGALLOC_GFP);
+		page = alloc_page(GFP_PGTABLE);
 		if (!page)
 			return NULL;
 	}
diff --git a/arch/riscv/include/asm/pgalloc.h b/arch/riscv/include/asm/pgalloc.h
index 94043cf..7ff1cd7 100644
--- a/arch/riscv/include/asm/pgalloc.h
+++ b/arch/riscv/include/asm/pgalloc.h
@@ -69,8 +69,7 @@ static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 
 static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
 {
-	return (pmd_t *)__get_free_page(
-		GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_ZERO);
+	return (pmd_t *)__get_free_page(GFP_PGTABLE | __GFP_RETRY_MAYFAIL);
 }
 
 static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
@@ -84,15 +83,14 @@ static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
 
 static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
 {
-	return (pte_t *)__get_free_page(
-		GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_ZERO);
+	return (pte_t *)__get_free_page(GFP_PGTABLE | __GFP_RETRY_MAYFAIL);
 }
 
 static inline struct page *pte_alloc_one(struct mm_struct *mm)
 {
 	struct page *pte;
 
-	pte = alloc_page(GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_ZERO);
+	pte = alloc_page(GFP_PGTABLE | __GFP_RETRY_MAYFAIL);
 	if (likely(pte != NULL))
 		pgtable_page_ctor(pte);
 	return pte;
diff --git a/arch/sh/mm/pgtable.c b/arch/sh/mm/pgtable.c
index 5c8f924..324732dc5 100644
--- a/arch/sh/mm/pgtable.c
+++ b/arch/sh/mm/pgtable.c
@@ -2,8 +2,6 @@
 #include <linux/mm.h>
 #include <linux/slab.h>
 
-#define PGALLOC_GFP GFP_KERNEL | __GFP_ZERO
-
 static struct kmem_cache *pgd_cachep;
 #if PAGETABLE_LEVELS > 2
 static struct kmem_cache *pmd_cachep;
@@ -32,7 +30,7 @@ void pgtable_cache_init(void)
 
 pgd_t *pgd_alloc(struct mm_struct *mm)
 {
-	return kmem_cache_alloc(pgd_cachep, PGALLOC_GFP);
+	return kmem_cache_alloc(pgd_cachep, GFP_PGTABLE);
 }
 
 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
@@ -48,7 +46,7 @@ void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
 
 pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
 {
-	return kmem_cache_alloc(pmd_cachep, PGALLOC_GFP);
+	return kmem_cache_alloc(pmd_cachep, GFP_PGTABLE);
 }
 
 void pmd_free(struct mm_struct *mm, pmd_t *pmd)
diff --git a/arch/unicore32/include/asm/pgalloc.h b/arch/unicore32/include/asm/pgalloc.h
index 7cceabe..a3506e5 100644
--- a/arch/unicore32/include/asm/pgalloc.h
+++ b/arch/unicore32/include/asm/pgalloc.h
@@ -28,8 +28,6 @@ extern void free_pgd_slow(struct mm_struct *mm, pgd_t *pgd);
 #define pgd_alloc(mm)			get_pgd_slow(mm)
 #define pgd_free(mm, pgd)		free_pgd_slow(mm, pgd)
 
-#define PGALLOC_GFP	(GFP_KERNEL | __GFP_ZERO)
-
 /*
  * Allocate one PTE table.
  */
@@ -38,7 +36,7 @@ pte_alloc_one_kernel(struct mm_struct *mm)
 {
 	pte_t *pte;
 
-	pte = (pte_t *)__get_free_page(PGALLOC_GFP);
+	pte = (pte_t *)__get_free_page(GFP_PGTABLE);
 	if (pte)
 		clean_dcache_area(pte, PTRS_PER_PTE * sizeof(pte_t));
 
@@ -50,7 +48,7 @@ pte_alloc_one(struct mm_struct *mm)
 {
 	struct page *pte;
 
-	pte = alloc_pages(PGALLOC_GFP, 0);
+	pte = alloc_pages(GFP_PGTABLE, 0);
 	if (!pte)
 		return NULL;
 	if (!PageHighMem(pte)) {
diff --git a/arch/x86/kernel/espfix_64.c b/arch/x86/kernel/espfix_64.c
index aebd0d5..dae28cc 100644
--- a/arch/x86/kernel/espfix_64.c
+++ b/arch/x86/kernel/espfix_64.c
@@ -57,8 +57,6 @@
 # error "Need more virtual address space for the ESPFIX hack"
 #endif
 
-#define PGALLOC_GFP (GFP_KERNEL | __GFP_ZERO)
-
 /* This contains the *bottom* address of the espfix stack */
 DEFINE_PER_CPU_READ_MOSTLY(unsigned long, espfix_stack);
 DEFINE_PER_CPU_READ_MOSTLY(unsigned long, espfix_waddr);
@@ -172,7 +170,7 @@ void init_espfix_ap(int cpu)
 	pud_p = &espfix_pud_page[pud_index(addr)];
 	pud = *pud_p;
 	if (!pud_present(pud)) {
-		struct page *page = alloc_pages_node(node, PGALLOC_GFP, 0);
+		struct page *page = alloc_pages_node(node, GFP_PGTABLE, 0);
 
 		pmd_p = (pmd_t *)page_address(page);
 		pud = __pud(__pa(pmd_p) | (PGTABLE_PROT & ptemask));
@@ -184,7 +182,7 @@ void init_espfix_ap(int cpu)
 	pmd_p = pmd_offset(&pud, addr);
 	pmd = *pmd_p;
 	if (!pmd_present(pmd)) {
-		struct page *page = alloc_pages_node(node, PGALLOC_GFP, 0);
+		struct page *page = alloc_pages_node(node, GFP_PGTABLE, 0);
 
 		pte_p = (pte_t *)page_address(page);
 		pmd = __pmd(__pa(pte_p) | (PGTABLE_PROT & ptemask));
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 7bd0170..a5b1672 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -13,19 +13,17 @@ phys_addr_t physical_mask __ro_after_init = (1ULL << __PHYSICAL_MASK_SHIFT) - 1;
 EXPORT_SYMBOL(physical_mask);
 #endif
 
-#define PGALLOC_GFP (GFP_KERNEL_ACCOUNT | __GFP_ZERO)
-
 #ifdef CONFIG_HIGHPTE
 #define PGALLOC_USER_GFP __GFP_HIGHMEM
 #else
 #define PGALLOC_USER_GFP 0
 #endif
 
-gfp_t __userpte_alloc_gfp = PGALLOC_GFP | PGALLOC_USER_GFP;
+gfp_t __userpte_alloc_gfp = GFP_PGTABLE | __GFP_ACCOUNT | PGALLOC_USER_GFP;
 
 pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
 {
-	return (pte_t *)__get_free_page(PGALLOC_GFP & ~__GFP_ACCOUNT);
+	return (pte_t *)__get_free_page(GFP_PGTABLE);
 }
 
 pgtable_t pte_alloc_one(struct mm_struct *mm)
@@ -235,7 +233,7 @@ static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[], int count)
 {
 	int i;
 	bool failed = false;
-	gfp_t gfp = PGALLOC_GFP;
+	gfp_t gfp = GFP_PGTABLE | __GFP_ACCOUNT;
 
 	if (mm = &init_mm)
 		gfp &= ~__GFP_ACCOUNT;
@@ -401,14 +399,14 @@ static inline pgd_t *_pgd_alloc(void)
 	 * We allocate one page for pgd.
 	 */
 	if (!SHARED_KERNEL_PMD)
-		return (pgd_t *)__get_free_pages(PGALLOC_GFP,
+		return (pgd_t *)__get_free_pages(GFP_PGTABLE | __GFP_ACCOUNT,
 						 PGD_ALLOCATION_ORDER);
 
 	/*
 	 * Now PAE kernel is not running as a Xen domain. We can allocate
 	 * a 32-byte slab for pgd to save memory space.
 	 */
-	return kmem_cache_alloc(pgd_cache, PGALLOC_GFP);
+	return kmem_cache_alloc(pgd_cache, GFP_PGTABLE | __GFP_ACCOUNT);
 }
 
 static inline void _pgd_free(pgd_t *pgd)
@@ -422,7 +420,8 @@ static inline void _pgd_free(pgd_t *pgd)
 
 static inline pgd_t *_pgd_alloc(void)
 {
-	return (pgd_t *)__get_free_pages(PGALLOC_GFP, PGD_ALLOCATION_ORDER);
+	return (pgd_t *)__get_free_pages(GFP_PGTABLE | __GFP_ACCOUNT,
+						PGD_ALLOCATION_ORDER);
 }
 
 static inline void _pgd_free(pgd_t *pgd)
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 05e61e6..3d9cde6 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -1186,4 +1186,6 @@ static inline bool arch_has_pfn_modify_check(void)
 #define mm_pmd_folded(mm)	__is_defined(__PAGETABLE_PMD_FOLDED)
 #endif
 
+#define GFP_PGTABLE	(GFP_KERNEL | __GFP_ZERO)
+
 #endif /* _ASM_GENERIC_PGTABLE_H */
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index fbdf3ac..f60a5b8 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -143,7 +143,7 @@ static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
 	if (cache->nobjs >= min)
 		return 0;
 	while (cache->nobjs < max) {
-		page = (void *)__get_free_page(PGALLOC_GFP);
+		page = (void *)__get_free_page(GFP_PGTABLE);
 		if (!page)
 			return -ENOMEM;
 		cache->objects[cache->nobjs++] = page;
-- 
2.7.4