* [PATCH RESEND 0/3] arm64: Add PUD THP support for DAX and pfnmap
@ 2026-10-28 12:14 Jinjiang Tu
2026-10-28 12:14 ` [PATCH RESEND 1/3] mm: define generic pudp_invalidate() implementation Jinjiang Tu
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Jinjiang Tu @ 2026-10-28 12:14 UTC (permalink / raw)
To: akpm, david, ljs, catalin.marinas, will, mark.rutland,
ryan.roberts, peterx, dave.jiang, linux-arm-kernel, linux-mm
Cc: wangkefeng.wang, sunnanyong, tujinjiang
This series adds PUD THP support for arm64, enabling PUD THP for DAX
and pfnmap.
Patch 1 moves the identical pudp_invalidate() implementations from x86
and riscv to a generic location so arm64 can reuse it.
Patch 2 is a minor cleanup that simplifies pmd_special/pmd_mkspecial.
Patch 3 adds the necessary PUD page table helpers and selects
HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD.
Jinjiang Tu (3):
mm: define generic pudp_invalidate() implementation
arm64: simplify pmd_special and pmd_mkspecial
arm64: Add PUD THP support for DAX and pfnmap
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/pgtable.h | 71 +++++++++++++++-----
arch/powerpc/include/asm/book3s/64/pgtable.h | 1 +
arch/riscv/include/asm/pgtable.h | 3 -
arch/riscv/mm/pgtable.c | 9 ---
arch/x86/include/asm/pgtable.h | 3 -
arch/x86/mm/pgtable.c | 12 ----
include/linux/pgtable.h | 7 ++
mm/pgtable-generic.c | 14 ++++
9 files changed, 77 insertions(+), 44 deletions(-)
--
2.43.0
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH RESEND 1/3] mm: define generic pudp_invalidate() implementation 2026-10-28 12:14 [PATCH RESEND 0/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu @ 2026-10-28 12:14 ` Jinjiang Tu 2026-10-28 12:14 ` [PATCH RESEND 2/3] arm64: simplify pmd_special and pmd_mkspecial Jinjiang Tu 2026-10-28 12:14 ` [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu 2 siblings, 0 replies; 6+ messages in thread From: Jinjiang Tu @ 2026-10-28 12:14 UTC (permalink / raw) To: akpm, david, ljs, catalin.marinas, will, mark.rutland, ryan.roberts, peterx, dave.jiang, linux-arm-kernel, linux-mm Cc: wangkefeng.wang, sunnanyong, tujinjiang x86 and riscv have identical pudp_invalidate() implementations. Move it to mm/pgtable-generic.c with the __HAVE_ARCH_PUDP_INVALIDATE override guard. PowerPC keeps its own implementation. In the later patch, arm64 will use the generic implementation too. No functional change intended. Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com> --- arch/powerpc/include/asm/book3s/64/pgtable.h | 1 + arch/riscv/include/asm/pgtable.h | 3 --- arch/riscv/mm/pgtable.c | 9 --------- arch/x86/include/asm/pgtable.h | 3 --- arch/x86/mm/pgtable.c | 12 ------------ include/linux/pgtable.h | 7 +++++++ mm/pgtable-generic.c | 14 ++++++++++++++ 7 files changed, 22 insertions(+), 27 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h index dff8790a047d..267d5e24f3b0 100644 --- a/arch/powerpc/include/asm/book3s/64/pgtable.h +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h @@ -1412,6 +1412,7 @@ static inline pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, #define __HAVE_ARCH_PMDP_INVALIDATE extern pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address, pmd_t *pmdp); +#define __HAVE_ARCH_PUDP_INVALIDATE extern pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address, pud_t *pudp); diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h index d48f90140841..0126d6ca5643 100644 --- a/arch/riscv/include/asm/pgtable.h +++ b/arch/riscv/include/asm/pgtable.h @@ -1162,9 +1162,6 @@ static inline pud_t pud_mkinvalid(pud_t pud) return __pud(pud_val(pud) & ~(_PAGE_PRESENT | _PAGE_PROT_NONE)); } -extern pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address, - pud_t *pudp); - static inline pud_t pud_modify(pud_t pud, pgprot_t newprot) { return pte_pud(pte_modify(pud_pte(pud), newprot)); diff --git a/arch/riscv/mm/pgtable.c b/arch/riscv/mm/pgtable.c index 9c4427d0b187..156e385e7db4 100644 --- a/arch/riscv/mm/pgtable.c +++ b/arch/riscv/mm/pgtable.c @@ -154,15 +154,6 @@ pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, return pmd; } -pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address, - pud_t *pudp) -{ - VM_WARN_ON_ONCE(!pud_present(*pudp)); - pud_t old = pudp_establish(vma, address, pudp, pud_mkinvalid(*pudp)); - - flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE); - return old; -} #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ pte_t pte_mkwrite(pte_t pte, struct vm_area_struct *vma) diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 000fc6c1ca37..ad7a40abef7d 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -1391,9 +1391,6 @@ static inline pud_t pudp_establish(struct vm_area_struct *vma, extern pmd_t pmdp_invalidate_ad(struct vm_area_struct *vma, unsigned long address, pmd_t *pmdp); -pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address, - pud_t *pudp); - /* * Page table pages are page-aligned. The lower half of the top * level is used for userspace and the top half for the kernel. diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 4a105f283cfb..591931d144f2 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -519,18 +519,6 @@ pmd_t pmdp_invalidate_ad(struct vm_area_struct *vma, unsigned long address, } #endif -#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \ - defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) -pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address, - pud_t *pudp) -{ - VM_WARN_ON_ONCE(!pud_present(*pudp)); - pud_t old = pudp_establish(vma, address, pudp, pud_mkinvalid(*pudp)); - flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE); - return old; -} -#endif - /** * reserve_top_address - Reserve a hole in the top of the kernel address space * @reserve: Size of hole to reserve diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 780fe849ff8b..0021eaf88e1d 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -1318,6 +1318,13 @@ extern pmd_t pmdp_invalidate_ad(struct vm_area_struct *vma, unsigned long address, pmd_t *pmdp); #endif +#ifndef __HAVE_ARCH_PUDP_INVALIDATE +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD +pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address, + pud_t *pudp); +#endif +#endif + #ifndef __HAVE_ARCH_PTE_SAME static inline int pte_same(pte_t pte_a, pte_t pte_b) { diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c index 6e83ce3801b8..1b7081fc4a75 100644 --- a/mm/pgtable-generic.c +++ b/mm/pgtable-generic.c @@ -229,6 +229,20 @@ pmd_t pmdp_invalidate_ad(struct vm_area_struct *vma, unsigned long address, } #endif +#ifndef __HAVE_ARCH_PUDP_INVALIDATE +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD +pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address, + pud_t *pudp) +{ + VM_WARN_ON_ONCE(!pud_present(*pudp)); + pud_t old = pudp_establish(vma, address, pudp, pud_mkinvalid(*pudp)); + + flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE); + return old; +} +#endif +#endif + #ifndef pmdp_collapse_flush pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address, pmd_t *pmdp) -- 2.43.0 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH RESEND 2/3] arm64: simplify pmd_special and pmd_mkspecial 2026-10-28 12:14 [PATCH RESEND 0/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu 2026-10-28 12:14 ` [PATCH RESEND 1/3] mm: define generic pudp_invalidate() implementation Jinjiang Tu @ 2026-10-28 12:14 ` Jinjiang Tu 2026-10-28 12:14 ` [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu 2 siblings, 0 replies; 6+ messages in thread From: Jinjiang Tu @ 2026-10-28 12:14 UTC (permalink / raw) To: akpm, david, ljs, catalin.marinas, will, mark.rutland, ryan.roberts, peterx, dave.jiang, linux-arm-kernel, linux-mm Cc: wangkefeng.wang, sunnanyong, tujinjiang Use pte_special() and pte_mkspecial() helper to simplify pmd_special() and pmd_mkspecial(), and kill unused set_pmd_bit() and clear_pmd_bit() helper. Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com> --- arch/arm64/include/asm/pgtable.h | 19 ++----------------- 1 file changed, 2 insertions(+), 17 deletions(-) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 763c5a411d64..7de2487e4d35 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -240,18 +240,6 @@ static inline pte_t set_pte_bit(pte_t pte, pgprot_t prot) return pte; } -static inline pmd_t clear_pmd_bit(pmd_t pmd, pgprot_t prot) -{ - pmd_val(pmd) &= ~pgprot_val(prot); - return pmd; -} - -static inline pmd_t set_pmd_bit(pmd_t pmd, pgprot_t prot) -{ - pmd_val(pmd) |= pgprot_val(prot); - return pmd; -} - static inline pte_t pte_mkwrite_novma(pte_t pte) { pte = set_pte_bit(pte, __pgprot(PTE_WRITE)); @@ -577,11 +565,8 @@ static inline pmd_t pmd_mkhuge(pmd_t pmd) } #ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP -#define pmd_special(pte) (!!((pmd_val(pte) & PTE_SPECIAL))) -static inline pmd_t pmd_mkspecial(pmd_t pmd) -{ - return set_pmd_bit(pmd, __pgprot(PTE_SPECIAL)); -} +#define pmd_special(pmd) pte_special(pmd_pte(pmd)) +#define pmd_mkspecial(pmd) pte_pmd(pte_mkspecial(pmd_pte(pmd))) #endif #define __pmd_to_phys(pmd) __pte_to_phys(pmd_pte(pmd)) -- 2.43.0 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap 2026-10-28 12:14 [PATCH RESEND 0/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu 2026-10-28 12:14 ` [PATCH RESEND 1/3] mm: define generic pudp_invalidate() implementation Jinjiang Tu 2026-10-28 12:14 ` [PATCH RESEND 2/3] arm64: simplify pmd_special and pmd_mkspecial Jinjiang Tu @ 2026-10-28 12:14 ` Jinjiang Tu 2026-10-29 3:39 ` kernel test robot 2026-10-29 12:14 ` sashiko-bot 2 siblings, 2 replies; 6+ messages in thread From: Jinjiang Tu @ 2026-10-28 12:14 UTC (permalink / raw) To: akpm, david, ljs, catalin.marinas, will, mark.rutland, ryan.roberts, peterx, dave.jiang, linux-arm-kernel, linux-mm Cc: wangkefeng.wang, sunnanyong, tujinjiang Add the necessary page table functions to deal with PUD THP, this enables PUD THP for DAX and pfnmap. I tested with CONFIG_DEBUG_VM_PGTABLE and CONFIG_PAGE_TABLE_CHECK enabled. I wrote a test driver that invokes vmf_insert_pfn_pud() in the huge_fault callback. Page table setup works as expected with no errors, and userspace read/write access to the PUD-sized mapping is verified correct. Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com> --- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/pgtable.h | 52 ++++++++++++++++++++++++++++++++ 2 files changed, 53 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index cfef22aee709..4f988f23acfb 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -173,6 +173,7 @@ config ARM64 select HAVE_ARCH_THREAD_STRUCT_WHITELIST select HAVE_ARCH_TRACEHOOK select HAVE_ARCH_TRANSPARENT_HUGEPAGE + select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if PAGE_SIZE_4KB select HAVE_ARCH_VMAP_STACK select HAVE_ARM_SMCCC select HAVE_ASM_MODVERSIONS diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 7de2487e4d35..feca481b2079 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -569,6 +569,11 @@ static inline pmd_t pmd_mkhuge(pmd_t pmd) #define pmd_mkspecial(pmd) pte_pmd(pte_mkspecial(pmd_pte(pmd))) #endif +#ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP +#define pud_special(pud) pte_special(pud_pte(pud)) +#define pud_mkspecial(pud) pte_pud(pte_mkspecial(pud_pte(pud))) +#endif + #define __pmd_to_phys(pmd) __pte_to_phys(pmd_pte(pmd)) #define __phys_to_pmd_val(phys) __phys_to_pte_val(phys) #define pmd_pfn(pmd) ((__pmd_to_phys(pmd) & PMD_MASK) >> PAGE_SHIFT) @@ -577,8 +582,15 @@ static inline pmd_t pmd_mkhuge(pmd_t pmd) #define pud_young(pud) pte_young(pud_pte(pud)) #define pud_mkyoung(pud) pte_pud(pte_mkyoung(pud_pte(pud))) #define pud_mkwrite_novma(pud) pte_pud(pte_mkwrite_novma(pud_pte(pud))) +#define pud_mkwrite(pud) pud_mkwrite_novma(pud) #define pud_mkvalid_k(pud) pte_pud(pte_mkvalid_k(pud_pte(pud))) #define pud_write(pud) pte_write(pud_pte(pud)) +#define pud_dirty(pud) pte_dirty(pud_pte(pud)) +#define pud_wrprotect(pud) pte_pud(pte_wrprotect(pud_pte(pud))) +#define pud_mkdirty(pud) pte_pud(pte_mkdirty(pud_pte(pud))) +#define pud_mkold(pud) pte_pud(pte_mkold(pud_pte(pud))) +#define pud_mkinvalid(pud) pte_pud(pte_mkinvalid(pud_pte(pud))) +#define pud_mkclean(pud) pte_pud(pte_mkclean(pud_pte(pud))) static inline pud_t pud_mkhuge(pud_t pud) { @@ -826,6 +838,13 @@ static inline bool pud_leaf(pud_t pud) #define pud_user(pud) pte_user(pud_pte(pud)) #define pud_user_exec(pud) pte_user_exec(pud_pte(pud)) +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD +static inline int pud_trans_huge(pud_t pud) +{ + return pud_present(pud) && !pud_table(__pud(pud_val(pud) | PTE_VALID)); +} +#endif + static inline bool pgtable_l4_enabled(void); static inline void set_pud(pud_t *pudp, pud_t pud) @@ -1183,6 +1202,11 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot) return pte_pmd(pte_modify(pmd_pte(pmd), newprot)); } +static inline pud_t pud_modify(pud_t pud, pgprot_t newprot) +{ + return pte_pud(pte_modify(pud_pte(pud), newprot)); +} + extern int __ptep_set_access_flags_anysz(struct vm_area_struct *vma, unsigned long address, pte_t *ptep, pte_t entry, int dirty, @@ -1207,6 +1231,16 @@ static inline int pmdp_set_access_flags(struct vm_area_struct *vma, } #endif +#ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP +static inline int pudp_set_access_flags(struct vm_area_struct *vma, + unsigned long address, pud_t *pudp, + pud_t entry, int dirty) +{ + return __ptep_set_access_flags_anysz(vma, address, (pte_t *)pudp, + pud_pte(entry), dirty, PUD_SIZE); +} +#endif + #ifdef CONFIG_PAGE_TABLE_CHECK static inline bool pte_user_accessible_page(struct mm_struct *mm, unsigned long addr, pte_t pte) { @@ -1281,6 +1315,14 @@ static inline bool pmdp_test_and_clear_young(struct vm_area_struct *vma, } #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG */ +#ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP +static inline bool pudp_test_and_clear_young(struct vm_area_struct *vma, + unsigned long address, pud_t *pudp) +{ + return __ptep_test_and_clear_young(vma, address, (pte_t *)pudp); +} +#endif + static inline pte_t __ptep_get_and_clear_anysz(struct mm_struct *mm, unsigned long address, pte_t *ptep, @@ -1443,6 +1485,15 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma, } #endif +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD +static inline pud_t pudp_establish(struct vm_area_struct *vma, + unsigned long address, pud_t *pudp, pud_t pud) +{ + page_table_check_pud_set(vma->vm_mm, address, pudp, pud); + return __pud(xchg_relaxed(&pud_val(*pudp), pud_val(pud))); +} +#endif + /* * Encode and decode a swap entry: * bits 0-1: present (must be zero) @@ -1517,6 +1568,7 @@ static inline void update_mmu_cache_range(struct vm_fault *vmf, #define update_mmu_cache(vma, addr, ptep) \ update_mmu_cache_range(NULL, vma, addr, ptep, 1) #define update_mmu_cache_pmd(vma, address, pmd) do { } while (0) +#define update_mmu_cache_pud(vma, address, pud) do { } while (0) #ifdef CONFIG_ARM64_PA_BITS_52 #define phys_to_ttbr(addr) (((addr) | ((addr) >> 46)) & TTBR_BADDR_MASK_52) -- 2.43.0 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap 2026-10-28 12:14 ` [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu @ 2026-10-29 3:39 ` kernel test robot 2026-10-29 12:14 ` sashiko-bot 1 sibling, 0 replies; 6+ messages in thread From: kernel test robot @ 2026-10-29 3:39 UTC (permalink / raw) To: Jinjiang Tu, akpm, david, ljs, catalin.marinas, will, mark.rutland, ryan.roberts, peterx, dave.jiang, linux-arm-kernel, linux-mm Cc: oe-kbuild-all, wangkefeng.wang, sunnanyong, tujinjiang Hi Jinjiang, kernel test robot noticed the following build errors: [auto build test ERROR on akpm-mm/mm-everything] [also build test ERROR on arm64/for-next/core powerpc/next powerpc/fixes tip/x86/core tip/x86/mm linus/master v7.3 next-20261027] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/Jinjiang-Tu/mm-define-generic-pudp_invalidate-implementation/20261028-201402 base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything patch link: https://lore.kernel.org/r/20261028121404.853944-4-tujinjiang%40huawei.com patch subject: [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap config: arm64-allnoconfig (https://download.01.org/0day-ci/archive/20261029/202610291125.dNGHD2Vr-lkp@intel.com/config) compiler: aarch64-linux-gcc (GCC) 16.2.0 reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20261029/202610291125.dNGHD2Vr-lkp@intel.com/reproduce) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot <lkp@intel.com> | Closes: https://lore.kernel.org/oe-kbuild-all/202610291125.dNGHD2Vr-lkp@intel.com/ All errors (new ones prefixed by >>): In file included from arch/arm64/include/asm/io.h:13, from include/linux/io.h:12, from include/linux/irq.h:20, from include/asm-generic/hardirq.h:17, from arch/arm64/include/asm/hardirq.h:17, from include/linux/hardirq.h:11, from include/linux/interrupt.h:11, from include/linux/trace_recursion.h:5, from include/linux/ftrace.h:10, from arch/arm64/kernel/asm-offsets.c:13: >> include/linux/pgtable.h:2098:19: error: redefinition of 'pud_trans_huge' 2098 | static inline int pud_trans_huge(pud_t pud) | ^~~~~~~~~~~~~~ In file included from include/linux/pgtable.h:6: arch/arm64/include/asm/pgtable.h:842:19: note: previous definition of 'pud_trans_huge' with type 'int(pud_t)' 842 | static inline int pud_trans_huge(pud_t pud) | ^~~~~~~~~~~~~~ make[3]: *** [scripts/Makefile.build:185: arch/arm64/kernel/asm-offsets.s] Error 1 make[3]: Target 'prepare' not remade because of errors. make[2]: *** [Makefile:1416: prepare0] Error 2 make[2]: Target 'prepare' not remade because of errors. make[1]: *** [Makefile:248: __sub-make] Error 2 make[1]: Target 'prepare' not remade because of errors. make: *** [Makefile:248: __sub-make] Error 2 make: Target 'prepare' not remade because of errors. vim +/pud_trans_huge +2098 include/linux/pgtable.h 1501899a898dfb5 include/asm-generic/pgtable.h Dan Williams 2017-11-29 2095 a00cc7d9dd93d66 include/asm-generic/pgtable.h Matthew Wilcox 2017-02-24 2096 #if !defined(CONFIG_TRANSPARENT_HUGEPAGE) || \ bcd0dea5f4fb3d0 include/linux/pgtable.h Liu Shixin 2022-08-29 2097 !defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) a00cc7d9dd93d66 include/asm-generic/pgtable.h Matthew Wilcox 2017-02-24 @2098 static inline int pud_trans_huge(pud_t pud) a00cc7d9dd93d66 include/asm-generic/pgtable.h Matthew Wilcox 2017-02-24 2099 { a00cc7d9dd93d66 include/asm-generic/pgtable.h Matthew Wilcox 2017-02-24 2100 return 0; a00cc7d9dd93d66 include/asm-generic/pgtable.h Matthew Wilcox 2017-02-24 2101 } a00cc7d9dd93d66 include/asm-generic/pgtable.h Matthew Wilcox 2017-02-24 2102 #endif a00cc7d9dd93d66 include/asm-generic/pgtable.h Matthew Wilcox 2017-02-24 2103 -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap 2026-10-28 12:14 ` [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu 2026-10-29 3:39 ` kernel test robot @ 2026-10-29 12:14 ` sashiko-bot 1 sibling, 0 replies; 6+ messages in thread From: sashiko-bot @ 2026-10-29 12:14 UTC (permalink / raw) To: Jinjiang Tu, akpm, david, ljs, catalin.marinas, will, mark.rutland, ryan.roberts, peterx, dave.jiang, linux-mm Cc: wangkefeng.wang, sunnanyong Thank you for your contribution! Sashiko AI review found 4 potential issue(s) to consider: - [High] arm64: mm: local-only TLB flush in pudp_set_access_flags() causes fault livelock - [High] arm64: mm: missing pudp_set_wrprotect() loses HAFDBS dirty bits and triggers warning - [High] arm64: mm: missing pudp_huge_get_and_clear() loses concurrent HAFDBS A/D updates - [Low] arm64: mm: redefinition of pud_trans_huge() when CONFIG_TRANSPARENT_HUGEPAGE=n -- commit 7dc812ccee714c3818da8b998f785b9073deeacd Author: Jinjiang Tu <tujinjiang@huawei.com> arm64: Add PUD THP support for DAX and pfnmap This patch adds PUD transparent hugepage page table helpers on arm64 and enables HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD for 4KB page size configurations to support PUD THP for DAX and pfnmap mappings. > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > index 7de2487e4d353..feca481b20795 100644 > --- a/arch/arm64/include/asm/pgtable.h > +++ b/arch/arm64/include/asm/pgtable.h [ ... ] > @@ -826,6 +838,13 @@ static inline bool pud_leaf(pud_t pud) > #define pud_user(pud) pte_user(pud_pte(pud)) > #define pud_user_exec(pud) pte_user_exec(pud_pte(pud)) > > +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD > +static inline int pud_trans_huge(pud_t pud) > +{ > + return pud_present(pud) && !pud_table(__pud(pud_val(pud) | PTE_VALID)); > +} > +#endif [Severity: Low] Will this cause a redefinition error for pud_trans_huge() when building with CONFIG_PAGE_SIZE_4KB=y and CONFIG_TRANSPARENT_HUGEPAGE=n (for example, allnoconfig or tinyconfig)? In arch/arm64/Kconfig, config ARM64 selects HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD whenever PAGE_SIZE_4KB is enabled, even when CONFIG_TRANSPARENT_HUGEPAGE is disabled: select HAVE_ARCH_TRANSPARENT_HUGEPAGE select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if PAGE_SIZE_4KB However, include/linux/pgtable.h includes asm/pgtable.h and then provides a fallback definition of pud_trans_huge() whenever CONFIG_TRANSPARENT_HUGEPAGE is not defined: #if !defined(CONFIG_TRANSPARENT_HUGEPAGE) || \ !defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) static inline int pud_trans_huge(pud_t pud) { return 0; } #endif Should pud_trans_huge() in arch/arm64/include/asm/pgtable.h also be guarded by CONFIG_TRANSPARENT_HUGEPAGE (matching pmd_trans_huge() in the same file)? [ ... ] > @@ -1207,6 +1231,16 @@ static inline int pmdp_set_access_flags(struct vm_area_struct *vma, > } > #endif > > +#ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP > +static inline int pudp_set_access_flags(struct vm_area_struct *vma, > + unsigned long address, pud_t *pudp, > + pud_t entry, int dirty) > +{ > + return __ptep_set_access_flags_anysz(vma, address, (pte_t *)pudp, > + pud_pte(entry), dirty, PUD_SIZE); > +} > +#endif [Severity: High] Can delegating pudp_set_access_flags() to __ptep_set_access_flags_anysz() lead to an infinite spurious write page-fault livelock on remote CPUs? In arch/arm64/mm/fault.c, __ptep_set_access_flags_anysz() only invalidates the local CPU's TLB via TLBF_NOBROADCAST when upgrading a read-only entry to writable/dirty, relying on remote CPUs to invalidate their stale read-only TLB entries on a subsequent permission fault: if (pte_same(pte, entry)) return 0; ... /* * Invalidate the local stale read-only entry. Remote stale entries * may still cause page faults and be invalidated via * flush_tlb_fix_spurious_fault(). */ if (dirty) { ... __flush_tlb_range(vma, address, address + pgsize, pgsize, level, TLBF_NOWALKCACHE | TLBF_NOBROADCAST); } Suppose two CPUs fault in a shared PUD mapping as hardware read-only (PTE_RDONLY=1, such as on an initial read fault for fsdax, a PFNMAP/devdax mapping on a CPU without hardware DBM, or after copy_huge_pud() write-protects the PUD), and CPU A then writes to the mapping. CPU A updates *pudp via wp_huge_pud() -> insert_pud() -> pudp_set_access_flags() or huge_pud_set_accessed() -> touch_pud() -> pudp_set_access_flags(), flushing only CPU A's local TLB. When CPU B subsequently writes to the same PUD range, it takes a permission fault from its stale read-only local TLB entry and enters: __handle_mm_fault() huge_pud_set_accessed() touch_pud() pudp_set_access_flags() __ptep_set_access_flags_anysz() Because *pudp in memory already matches entry (with PTE_AF, PTE_DIRTY, and PTE_WRITE set and PTE_RDONLY cleared), pte_same(pte, entry) is true and __ptep_set_access_flags_anysz() returns 0 without flushing CPU B's TLB. Unlike the PTE and PMD paths, which call flush_tlb_fix_spurious_fault() and flush_tlb_fix_spurious_fault_pmd() when ptep_set_access_flags() or pmdp_set_access_flags() returns 0, neither touch_pud(), huge_pud_set_accessed(), __handle_mm_fault(), nor insert_pud() performs a local TLB flush on a spurious PUD fault. Wouldn't CPU B return to userspace with the stale read-only PUD TLB entry still in place and fault in an infinite loop? [ ... ] > @@ -1281,6 +1315,14 @@ static inline bool pmdp_test_and_clear_young(struct vm_area_struct *vma, > } > #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG */ > > +#ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP > +static inline bool pudp_test_and_clear_young(struct vm_area_struct *vma, > + unsigned long address, pud_t *pudp) > +{ > + return __ptep_test_and_clear_young(vma, address, (pte_t *)pudp); > +} > +#endif > + > static inline pte_t __ptep_get_and_clear_anysz(struct mm_struct *mm, > unsigned long address, > pte_t *ptep, [Severity: High] Should arm64 also define __HAVE_ARCH_PUDP_HUGE_GET_AND_CLEAR and implement pudp_huge_get_and_clear() via __ptep_get_and_clear_anysz(..., PUD_SIZE)? __ptep_get_and_clear_anysz() in arch/arm64/include/asm/pgtable.h already uses an atomic xchg_relaxed() and has a PUD_SIZE case for page_table_check_pud_clear(). Without an arch definition of pudp_huge_get_and_clear(), arm64 falls back to the generic implementation in include/linux/pgtable.h: #ifndef __HAVE_ARCH_PUDP_HUGE_GET_AND_CLEAR static inline pud_t pudp_huge_get_and_clear(struct mm_struct *mm, unsigned long address, pud_t *pudp) { pud_t pud = *pudp; pud_clear(pudp); page_table_check_pud_clear(mm, address, pud); return pud; } #endif When splitting a DAX PUD via split_huge_pud() -> __split_huge_pud_locked() -> pudp_huge_clear_flush() -> pudp_huge_get_and_clear(), __split_huge_pud_locked() propagates the dirty and young bits from old_pud to the folio: old_pud = pudp_huge_clear_flush(vma, haddr, pud); if (!vma_is_dax(vma)) return; page = pud_page(old_pud); folio = page_folio(page); if (!folio_test_dirty(folio) && pud_dirty(old_pud)) folio_mark_dirty(folio); if (!folio_test_referenced(folio) && pud_young(old_pud)) folio_set_referenced(folio); On systems with FEAT_HAFDBS, couldn't a concurrent hardware access or dirty state update between the non-atomic read of *pudp and pud_clear(pudp) be lost? [ ... ] > @@ -1443,6 +1485,15 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma, > } > #endif > > +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD > +static inline pud_t pudp_establish(struct vm_area_struct *vma, > + unsigned long address, pud_t *pudp, pud_t pud) > +{ > + page_table_check_pud_set(vma->vm_mm, address, pudp, pud); > + return __pud(xchg_relaxed(&pud_val(*pudp), pud_val(pud))); > +} > +#endif [Severity: High] Is __HAVE_ARCH_PUDP_SET_WRPROTECT with pudp_set_wrprotect() also needed here, matching pmdp_set_wrprotect() right above pmdp_establish()? Without an architecture-specific pudp_set_wrprotect() wrapping __ptep_set_wrprotect(), arm64 uses the generic fallback in include/linux/pgtable.h: static inline void pudp_set_wrprotect(struct mm_struct *mm, unsigned long address, pud_t *pudp) { pud_t old_pud = *pudp; set_pud_at(mm, address, pudp, pud_wrprotect(old_pud)); } When fork() copies a COW PUD via copy_page_range() -> copy_p4d_range() -> copy_pud_range() -> copy_huge_pud() -> pudp_set_wrprotect(): 1. The non-atomic read of *pudp followed by set_pud_at() races with hardware AF/DBM updates (FEAT_HAFDBS), unlike __ptep_set_wrprotect() which uses a cmpxchg_relaxed() loop to atomically transfer hardware dirty state to PTE_DIRTY while setting PTE_RDONLY and clearing PTE_WRITE. 2. Updating a live valid PUD in place via set_pud_at() -> __set_ptes_anysz() calls __check_safe_pte_update() in arch/arm64/mm/mmu.c, which triggers VM_WARN_ONCE() when the entry is old or writable-clean on a live mm: VM_WARN_ONCE(!pte_young(pte), "%s: racy access flag clearing: %s -> %s", __func__, pte_str_old, pte_str); VM_WARN_ONCE(pte_write(old_pte) && !pte_dirty(pte), "%s: racy dirty state clearing: %s -> %s", __func__, pte_str_old, pte_str); 3. set_pud_at() also runs __sync_cache_and_tags() across PUD_SIZE >> PAGE_SHIFT (262,144) pages unnecessarily when only write-protecting an existing entry. -- Sashiko AI review · https://sashiko.dev/#/patchset/20261028121404.853944-1-tujinjiang@huawei.com?part=3 ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2026-10-29 12:14 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2026-10-28 12:14 [PATCH RESEND 0/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu 2026-10-28 12:14 ` [PATCH RESEND 1/3] mm: define generic pudp_invalidate() implementation Jinjiang Tu 2026-10-28 12:14 ` [PATCH RESEND 2/3] arm64: simplify pmd_special and pmd_mkspecial Jinjiang Tu 2026-10-28 12:14 ` [PATCH RESEND 3/3] arm64: Add PUD THP support for DAX and pfnmap Jinjiang Tu 2026-10-29 3:39 ` kernel test robot 2026-10-29 12:14 ` sashiko-bot
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