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Sun, 16 Feb 2020 11:41:09 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id VGVzW0Ckh2uU; Sun, 16 Feb 2020 11:41:09 +0100 (CET) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id B4E908B755; Sun, 16 Feb 2020 11:41:07 +0100 (CET) Subject: Re: [PATCH v2 07/13] powerpc: add support for folded p4d page tables To: Mike Rapoport , linux-kernel@vger.kernel.org Cc: Andrew Morton , Arnd Bergmann , Benjamin Herrenschmidt , Brian Cain , Catalin Marinas , Fenghua Yu , Geert Uytterhoeven , Guan Xuetao , James Morse , Jonas Bonn , Julien Thierry , Ley Foon Tan , Marc Zyngier , Michael Ellerman , Paul Mackerras , Rich Felker , Russell King , Stafford Horne , Stefan Kristiansson , Suzuki K Poulose , Tony Luck , Will Deacon , Yoshinori Sato , kvmarm@lists.cs.columbia.edu, kvm-ppc@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org, nios2-dev@lists.rocketboards.org, openrisc@lists.librecores.org, uclinux-h8-devel@lists.sourceforge.jp, Mike Rapoport References: <20200216081843.28670-1-rppt@kernel.org> <20200216081843.28670-8-rppt@kernel.org> From: Christophe Leroy Message-ID: Date: Sun, 16 Feb 2020 11:41:07 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200216081843.28670-8-rppt@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Le 16/02/2020 =C3=A0 09:18, Mike Rapoport a =C3=A9crit=C2=A0: > From: Mike Rapoport >=20 > Implement primitives necessary for the 4th level folding, add walks of = p4d > level where appropriate and replace 5level-fixup.h with pgtable-nop4d.h= . I don't think it is worth adding all this additionnals walks of p4d,=20 this patch could be limited to changes like: - pud =3D pud_offset(pgd, gpa); + pud =3D pud_offset(p4d_offset(pgd, gpa), gpa); The additionnal walks should be added through another patch the day=20 powerpc need them. See below for more comments. >=20 > Signed-off-by: Mike Rapoport > Tested-by: Christophe Leroy # 8xx and 83xx > --- > arch/powerpc/include/asm/book3s/32/pgtable.h | 1 - > arch/powerpc/include/asm/book3s/64/hash.h | 4 +- > arch/powerpc/include/asm/book3s/64/pgalloc.h | 4 +- > arch/powerpc/include/asm/book3s/64/pgtable.h | 58 ++++++++++-------- > arch/powerpc/include/asm/book3s/64/radix.h | 6 +- > arch/powerpc/include/asm/nohash/32/pgtable.h | 1 - > arch/powerpc/include/asm/nohash/64/pgalloc.h | 2 +- > .../include/asm/nohash/64/pgtable-4k.h | 32 +++++----- > arch/powerpc/include/asm/nohash/64/pgtable.h | 6 +- > arch/powerpc/include/asm/pgtable.h | 8 +++ > arch/powerpc/kvm/book3s_64_mmu_radix.c | 59 ++++++++++++++++--= - > arch/powerpc/lib/code-patching.c | 7 ++- > arch/powerpc/mm/book3s32/mmu.c | 2 +- > arch/powerpc/mm/book3s32/tlb.c | 4 +- > arch/powerpc/mm/book3s64/hash_pgtable.c | 4 +- > arch/powerpc/mm/book3s64/radix_pgtable.c | 19 ++++-- > arch/powerpc/mm/book3s64/subpage_prot.c | 6 +- > arch/powerpc/mm/hugetlbpage.c | 28 +++++---- > arch/powerpc/mm/kasan/kasan_init_32.c | 8 +-- > arch/powerpc/mm/mem.c | 4 +- > arch/powerpc/mm/nohash/40x.c | 4 +- > arch/powerpc/mm/nohash/book3e_pgtable.c | 15 +++-- > arch/powerpc/mm/pgtable.c | 25 +++++++- > arch/powerpc/mm/pgtable_32.c | 28 +++++---- > arch/powerpc/mm/pgtable_64.c | 10 ++-- > arch/powerpc/mm/ptdump/hashpagetable.c | 20 ++++++- > arch/powerpc/mm/ptdump/ptdump.c | 22 ++++++- > arch/powerpc/xmon/xmon.c | 17 +++++- > 28 files changed, 284 insertions(+), 120 deletions(-) >=20 > diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerp= c/include/asm/book3s/32/pgtable.h > index 5b39c11e884a..39ec11371be0 100644 > --- a/arch/powerpc/include/asm/book3s/32/pgtable.h > +++ b/arch/powerpc/include/asm/book3s/32/pgtable.h > @@ -2,7 +2,6 @@ > #ifndef _ASM_POWERPC_BOOK3S_32_PGTABLE_H > #define _ASM_POWERPC_BOOK3S_32_PGTABLE_H > =20 > -#define __ARCH_USE_5LEVEL_HACK > #include > =20 > #include > diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/i= nclude/asm/book3s/64/hash.h > index 2781ebf6add4..876d1528c2cf 100644 > --- a/arch/powerpc/include/asm/book3s/64/hash.h > +++ b/arch/powerpc/include/asm/book3s/64/hash.h > @@ -134,9 +134,9 @@ static inline int get_region_id(unsigned long ea) > =20 > #define hash__pmd_bad(pmd) (pmd_val(pmd) & H_PMD_BAD_BITS) > #define hash__pud_bad(pud) (pud_val(pud) & H_PUD_BAD_BITS) > -static inline int hash__pgd_bad(pgd_t pgd) > +static inline int hash__p4d_bad(p4d_t p4d) > { > - return (pgd_val(pgd) =3D=3D 0); > + return (p4d_val(p4d) =3D=3D 0); > } > #ifdef CONFIG_STRICT_KERNEL_RWX > extern void hash__mark_rodata_ro(void); > diff --git a/arch/powerpc/include/asm/book3s/64/pgalloc.h b/arch/powerp= c/include/asm/book3s/64/pgalloc.h > index a41e91bd0580..69c5b051734f 100644 > --- a/arch/powerpc/include/asm/book3s/64/pgalloc.h > +++ b/arch/powerpc/include/asm/book3s/64/pgalloc.h > @@ -85,9 +85,9 @@ static inline void pgd_free(struct mm_struct *mm, pgd= _t *pgd) > kmem_cache_free(PGT_CACHE(PGD_INDEX_SIZE), pgd); > } > =20 > -static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, pud_= t *pud) > +static inline void p4d_populate(struct mm_struct *mm, p4d_t *pgd, pud_= t *pud) > { > - *pgd =3D __pgd(__pgtable_ptr_val(pud) | PGD_VAL_BITS); > + *pgd =3D __p4d(__pgtable_ptr_val(pud) | PGD_VAL_BITS); > } > =20 > static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned lon= g addr) > diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerp= c/include/asm/book3s/64/pgtable.h > index 201a69e6a355..ddddbafff0ab 100644 > --- a/arch/powerpc/include/asm/book3s/64/pgtable.h > +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h > @@ -2,7 +2,7 @@ > #ifndef _ASM_POWERPC_BOOK3S_64_PGTABLE_H_ > #define _ASM_POWERPC_BOOK3S_64_PGTABLE_H_ > =20 > -#include > +#include > =20 > #ifndef __ASSEMBLY__ > #include > @@ -251,7 +251,7 @@ extern unsigned long __pmd_frag_size_shift; > /* Bits to mask out from a PUD to get to the PMD page */ > #define PUD_MASKED_BITS 0xc0000000000000ffUL > /* Bits to mask out from a PGD to get to the PUD page */ > -#define PGD_MASKED_BITS 0xc0000000000000ffUL > +#define P4D_MASKED_BITS 0xc0000000000000ffUL > =20 > /* > * Used as an indicator for rcu callback functions > @@ -949,54 +949,60 @@ static inline bool pud_access_permitted(pud_t pud= , bool write) > return pte_access_permitted(pud_pte(pud), write); > } > =20 > -#define pgd_write(pgd) pte_write(pgd_pte(pgd)) > +#define __p4d_raw(x) ((p4d_t) { __pgd_raw(x) }) > +static inline __be64 p4d_raw(p4d_t x) > +{ > + return pgd_raw(x.pgd); > +} > + Shouldn't this be defined in asm/pgtable-be-types.h, just like other=20 __pxx_raw() ? > +#define p4d_write(p4d) pte_write(p4d_pte(p4d)) > =20 > -static inline void pgd_clear(pgd_t *pgdp) > +static inline void p4d_clear(p4d_t *p4dp) > { > - *pgdp =3D __pgd(0); > + *p4dp =3D __p4d(0); > } > =20 > -static inline int pgd_none(pgd_t pgd) > +static inline int p4d_none(p4d_t p4d) > { > - return !pgd_raw(pgd); > + return !p4d_raw(p4d); > } > =20 > -static inline int pgd_present(pgd_t pgd) > +static inline int p4d_present(p4d_t p4d) > { > - return !!(pgd_raw(pgd) & cpu_to_be64(_PAGE_PRESENT)); > + return !!(p4d_raw(p4d) & cpu_to_be64(_PAGE_PRESENT)); > } > =20 > -static inline pte_t pgd_pte(pgd_t pgd) > +static inline pte_t p4d_pte(p4d_t p4d) > { > - return __pte_raw(pgd_raw(pgd)); > + return __pte_raw(p4d_raw(p4d)); > } > =20 > -static inline pgd_t pte_pgd(pte_t pte) > +static inline p4d_t pte_p4d(pte_t pte) > { > - return __pgd_raw(pte_raw(pte)); > + return __p4d_raw(pte_raw(pte)); > } > =20 > -static inline int pgd_bad(pgd_t pgd) > +static inline int p4d_bad(p4d_t p4d) > { > if (radix_enabled()) > - return radix__pgd_bad(pgd); > - return hash__pgd_bad(pgd); > + return radix__p4d_bad(p4d); > + return hash__p4d_bad(p4d); > } > =20 > -#define pgd_access_permitted pgd_access_permitted > -static inline bool pgd_access_permitted(pgd_t pgd, bool write) > +#define p4d_access_permitted p4d_access_permitted > +static inline bool p4d_access_permitted(p4d_t p4d, bool write) > { > - return pte_access_permitted(pgd_pte(pgd), write); > + return pte_access_permitted(p4d_pte(p4d), write); > } > =20 > -extern struct page *pgd_page(pgd_t pgd); > +extern struct page *p4d_page(p4d_t p4d); > =20 > /* Pointers in the page table tree are physical addresses */ > #define __pgtable_ptr_val(ptr) __pa(ptr) > =20 > #define pmd_page_vaddr(pmd) __va(pmd_val(pmd) & ~PMD_MASKED_BITS) > #define pud_page_vaddr(pud) __va(pud_val(pud) & ~PUD_MASKED_BITS) > -#define pgd_page_vaddr(pgd) __va(pgd_val(pgd) & ~PGD_MASKED_BITS) > +#define p4d_page_vaddr(p4d) __va(p4d_val(p4d) & ~P4D_MASKED_BITS) > =20 > #define pgd_index(address) (((address) >> (PGDIR_SHIFT)) & (PTRS_PER_= PGD - 1)) > #define pud_index(address) (((address) >> (PUD_SHIFT)) & (PTRS_PER_PU= D - 1)) > @@ -1010,8 +1016,8 @@ extern struct page *pgd_page(pgd_t pgd); > =20 > #define pgd_offset(mm, address) ((mm)->pgd + pgd_index(address)) > =20 > -#define pud_offset(pgdp, addr) \ > - (((pud_t *) pgd_page_vaddr(*(pgdp))) + pud_index(addr)) > +#define pud_offset(p4dp, addr) \ > + (((pud_t *) p4d_page_vaddr(*(p4dp))) + pud_index(addr)) > #define pmd_offset(pudp,addr) \ > (((pmd_t *) pud_page_vaddr(*(pudp))) + pmd_index(addr)) > #define pte_offset_kernel(dir,addr) \ > @@ -1368,6 +1374,12 @@ static inline bool pud_is_leaf(pud_t pud) > return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE)); > } > =20 > +#define p4d_is_leaf p4d_is_leaf > +static inline bool p4d_is_leaf(p4d_t p4d) > +{ > + return !!(p4d_raw(p4d) & cpu_to_be64(_PAGE_PTE)); > +} > + > #define pgd_is_leaf pgd_is_leaf > #define pgd_leaf pgd_is_leaf > static inline bool pgd_is_leaf(pgd_t pgd) [...] > diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/= asm/pgtable.h > index 8cc543ed114c..0a05fddd7881 100644 > --- a/arch/powerpc/include/asm/pgtable.h > +++ b/arch/powerpc/include/asm/pgtable.h > @@ -139,6 +139,14 @@ static inline bool pud_is_leaf(pud_t pud) > } > #endif > =20 > +#ifndef p4d_is_leaf > +#define p4d_is_leaf p4d_is_leaf > +static inline bool p4d_is_leaf(p4d_t p4d) > +{ > + return false; > +} > +#endif > + > #ifndef pgd_is_leaf > #define pgd_is_leaf pgd_is_leaf > static inline bool pgd_is_leaf(pgd_t pgd) > diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/= book3s_64_mmu_radix.c > index 803940d79b73..5aacfa0b27ef 100644 > --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c > +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c > @@ -494,17 +494,39 @@ static void kvmppc_unmap_free_pud(struct kvm *kvm= , pud_t *pud, > pud_free(kvm->mm, pud); > } > =20 > +static void kvmppc_unmap_free_p4d(struct kvm *kvm, p4d_t *p4d, > + unsigned int lpid) > +{ > + unsigned long iu; > + p4d_t *p =3D p4d; > + > + for (iu =3D 0; iu < PTRS_PER_P4D; ++iu, ++p) { > + if (!p4d_present(*p)) > + continue; > + if (p4d_is_leaf(*p)) { > + p4d_clear(p); > + } else { > + pud_t *pud; > + > + pud =3D pud_offset(p, 0); > + kvmppc_unmap_free_pud(kvm, pud, lpid); > + p4d_clear(p); > + } > + } > + p4d_free(kvm->mm, p4d); > +} > + > void kvmppc_free_pgtable_radix(struct kvm *kvm, pgd_t *pgd, unsigned = int lpid) > { > unsigned long ig; > =20 > for (ig =3D 0; ig < PTRS_PER_PGD; ++ig, ++pgd) { > - pud_t *pud; > + p4d_t *p4d; > =20 > if (!pgd_present(*pgd)) > continue; > - pud =3D pud_offset(pgd, 0); > - kvmppc_unmap_free_pud(kvm, pud, lpid); > + p4d =3D p4d_offset(pgd, 0); > + kvmppc_unmap_free_p4d(kvm, p4d, lpid); > pgd_clear(pgd); > } > } > @@ -566,6 +588,7 @@ int kvmppc_create_pte(struct kvm *kvm, pgd_t *pgtab= le, pte_t pte, > unsigned long *rmapp, struct rmap_nested **n_rmap) > { > pgd_t *pgd; > + p4d_t *p4d, *new_p4d =3D NULL; > pud_t *pud, *new_pud =3D NULL; > pmd_t *pmd, *new_pmd =3D NULL; > pte_t *ptep, *new_ptep =3D NULL; > @@ -573,9 +596,15 @@ int kvmppc_create_pte(struct kvm *kvm, pgd_t *pgta= ble, pte_t pte, > =20 > /* Traverse the guest's 2nd-level tree, allocate new levels needed *= / > pgd =3D pgtable + pgd_index(gpa); > - pud =3D NULL; > + p4d =3D NULL; > if (pgd_present(*pgd)) > - pud =3D pud_offset(pgd, gpa); > + p4d =3D p4d_offset(pgd, gpa); > + else > + new_p4d =3D p4d_alloc_one(kvm->mm, gpa); > + > + pud =3D NULL; > + if (p4d_present(*p4d)) > + pud =3D pud_offset(p4d, gpa); Is it worth adding all this new code ? My understanding is that the series objective is to get rid of=20 __ARCH_HAS_5LEVEL_HACK, to to add support for 5 levels to an=20 architecture that not need it (at least for now). If we want to add support for 5 levels, it can be done later in another=20 patch. Here I think your change could be limited to: - pud =3D pud_offset(pgd, gpa); + pud =3D pud_offset(p4d_offset(pgd, gpa), gpa); > else > new_pud =3D pud_alloc_one(kvm->mm, gpa); > =20 > @@ -597,12 +626,18 @@ int kvmppc_create_pte(struct kvm *kvm, pgd_t *pgt= able, pte_t pte, > /* Now traverse again under the lock and change the tree */ > ret =3D -ENOMEM; > if (pgd_none(*pgd)) { > + if (!new_p4d) > + goto out_unlock; > + pgd_populate(kvm->mm, pgd, new_p4d); > + new_p4d =3D NULL; > + } > + if (p4d_none(*p4d)) { > if (!new_pud) > goto out_unlock; > - pgd_populate(kvm->mm, pgd, new_pud); > + p4d_populate(kvm->mm, p4d, new_pud); > new_pud =3D NULL; > } > - pud =3D pud_offset(pgd, gpa); > + pud =3D pud_offset(p4d, gpa); > if (pud_is_leaf(*pud)) { > unsigned long hgpa =3D gpa & PUD_MASK; > =20 > @@ -1220,6 +1255,7 @@ static ssize_t debugfs_radix_read(struct file *fi= le, char __user *buf, > pgd_t *pgt; > struct kvm_nested_guest *nested; > pgd_t pgd, *pgdp; > + p4d_t p4d, *p4dp; > pud_t pud, *pudp; > pmd_t pmd, *pmdp; > pte_t *ptep; > @@ -1298,7 +1334,14 @@ static ssize_t debugfs_radix_read(struct file *f= ile, char __user *buf, > continue; > } > =20 > - pudp =3D pud_offset(&pgd, gpa); > + p4dp =3D p4d_offset(&pgd, gpa); > + p4d =3D READ_ONCE(*p4dp); > + if (!(p4d_val(p4d) & _PAGE_PRESENT)) { > + gpa =3D (gpa & P4D_MASK) + P4D_SIZE; > + continue; > + } > + > + pudp =3D pud_offset(&p4d, gpa); Same, here you are forcing a useless read with READ_ONCE(). Your change could be limited to - pudp =3D pud_offset(&pgd, gpa); + pudp =3D pud_offset(p4d_offset(&pgd, gpa), gpa); This comment applies to many other places. > pud =3D READ_ONCE(*pudp); > if (!(pud_val(pud) & _PAGE_PRESENT)) { > gpa =3D (gpa & PUD_MASK) + PUD_SIZE; > diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-p= atching.c > index 3345f039a876..7a59f6863cec 100644 > --- a/arch/powerpc/lib/code-patching.c > +++ b/arch/powerpc/lib/code-patching.c > @@ -107,13 +107,18 @@ static inline int unmap_patch_area(unsigned long = addr) > pte_t *ptep; > pmd_t *pmdp; > pud_t *pudp; > + p4d_t *p4dp; > pgd_t *pgdp; > =20 > pgdp =3D pgd_offset_k(addr); > if (unlikely(!pgdp)) > return -EINVAL; > =20 > - pudp =3D pud_offset(pgdp, addr); > + p4dp =3D p4d_offset(pgdp, addr); > + if (unlikely(!p4dp)) > + return -EINVAL; > + > + pudp =3D pud_offset(p4dp, addr); > if (unlikely(!pudp)) > return -EINVAL; > =20 > diff --git a/arch/powerpc/mm/book3s32/mmu.c b/arch/powerpc/mm/book3s32/= mmu.c > index 0a1c65a2c565..b2fc3e71165c 100644 > --- a/arch/powerpc/mm/book3s32/mmu.c > +++ b/arch/powerpc/mm/book3s32/mmu.c > @@ -312,7 +312,7 @@ void hash_preload(struct mm_struct *mm, unsigned lo= ng ea) > =20 > if (!Hash) > return; > - pmd =3D pmd_offset(pud_offset(pgd_offset(mm, ea), ea), ea); > + pmd =3D pmd_offset(pud_offset(p4d_offset(pgd_offset(mm, ea), ea), ea)= , ea); If we continue like this, in ten years this like is going to be many=20 kilometers long. I think the above would be worth a generic helper. > if (!pmd_none(*pmd)) > add_hash_page(mm->context.id, ea, pmd_val(*pmd)); > } > diff --git a/arch/powerpc/mm/book3s32/tlb.c b/arch/powerpc/mm/book3s32/= tlb.c > index 2fcd321040ff..175bc33b41b7 100644 > --- a/arch/powerpc/mm/book3s32/tlb.c > +++ b/arch/powerpc/mm/book3s32/tlb.c > @@ -87,7 +87,7 @@ static void flush_range(struct mm_struct *mm, unsigne= d long start, > if (start >=3D end) > return; > end =3D (end - 1) | ~PAGE_MASK; > - pmd =3D pmd_offset(pud_offset(pgd_offset(mm, start), start), start); > + pmd =3D pmd_offset(pud_offset(p4d_offset(pgd_offset(mm, start), start= ), start), start); > for (;;) { > pmd_end =3D ((start + PGDIR_SIZE) & PGDIR_MASK) - 1; > if (pmd_end > end) > @@ -145,7 +145,7 @@ void flush_tlb_page(struct vm_area_struct *vma, uns= igned long vmaddr) > return; > } > mm =3D (vmaddr < TASK_SIZE)? vma->vm_mm: &init_mm; > - pmd =3D pmd_offset(pud_offset(pgd_offset(mm, vmaddr), vmaddr), vmaddr= ); > + pmd =3D pmd_offset(pud_offset(p4d_offset(pgd_offset(mm, vmaddr), vmad= dr), vmaddr), vmaddr); > if (!pmd_none(*pmd)) > flush_hash_pages(mm->context.id, vmaddr, pmd_val(*pmd), 1); > } > diff --git a/arch/powerpc/mm/book3s64/hash_pgtable.c b/arch/powerpc/mm/= book3s64/hash_pgtable.c > index 64733b9cb20a..9cd15937e88a 100644 > --- a/arch/powerpc/mm/book3s64/hash_pgtable.c > +++ b/arch/powerpc/mm/book3s64/hash_pgtable.c > @@ -148,6 +148,7 @@ void hash__vmemmap_remove_mapping(unsigned long sta= rt, > int hash__map_kernel_page(unsigned long ea, unsigned long pa, pgprot_= t prot) > { > pgd_t *pgdp; > + p4d_t *p4dp; > pud_t *pudp; > pmd_t *pmdp; > pte_t *ptep; > @@ -155,7 +156,8 @@ int hash__map_kernel_page(unsigned long ea, unsigne= d long pa, pgprot_t prot) > BUILD_BUG_ON(TASK_SIZE_USER64 > H_PGTABLE_RANGE); > if (slab_is_available()) { > pgdp =3D pgd_offset_k(ea); > - pudp =3D pud_alloc(&init_mm, pgdp, ea); > + p4dp =3D p4d_offset(pgdp, ea); > + pudp =3D pud_alloc(&init_mm, p4dp, ea); Could be a single line, without a new var. - pudp =3D pud_alloc(&init_mm, pgdp, ea); + pudp =3D pud_alloc(&init_mm, p4d_offset(pgdp, ea), ea); Same kind of comments as already done apply to the rest. Christophe