Re: [PATCH V2] mm: Introduce GFP_PGTABLE
From: Mike Rapoport
Date: Wed Jan 16 2019 - 01:55:45 EST
On Wed, Jan 16, 2019 at 11:51:32AM +0530, Anshuman Khandual wrote:
> 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@xxxxxxx>
> ---
> 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(-)
I wonder, what about the other arches? Do they use different GFP flags?
> 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
>
--
Sincerely yours,
Mike.