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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: 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 X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: cbcbde85-6452-49a8-2193-08dd57a88a20 X-MS-Exchange-CrossTenant-AuthSource: DS0PR12MB7726.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Feb 2025 03:32:34.3010 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: esEgplQ1/Wgu+5NrSWpyLtAOpKalIwvL5aLhxdXFBdlrdoVMYb/MKs6zaNI1hsrxZ7zd915Ds+NIfpuOYt7Zgg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR12MB7991 Currently DAX folio/page reference counts are managed differently to normal pages. To allow these to be managed the same as normal pages introduce vmf_insert_folio_pud. This will map the entire PUD-sized folio and take references as it would for a normally mapped page. This is distinct from the current mechanism, vmf_insert_pfn_pud, which simply inserts a special devmap PUD entry into the page table without holding a reference to the page for the mapping. Signed-off-by: Alistair Popple Reviewed-by: Dan Williams Acked-by: David Hildenbrand --- Changes for v7: - Added a comment clarifying why we can insert without a reference. Changes for v5: - Removed is_huge_zero_pud() as it's unlikely to ever be implemented. - Minor code clean-up suggested by David. --- include/linux/huge_mm.h | 2 +- mm/huge_memory.c | 99 ++++++++++++++++++++++++++++++++++++----- 2 files changed, 89 insertions(+), 12 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 2bd1811..b60e2d4 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -39,6 +39,8 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write); vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write); +vm_fault_t vmf_insert_folio_pud(struct vm_fault *vmf, struct folio *folio, + bool write); enum transparent_hugepage_flag { TRANSPARENT_HUGEPAGE_UNSUPPORTED, diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 3159ae0..1da6047 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1482,19 +1482,17 @@ static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, struct mm_struct *mm = vma->vm_mm; pgprot_t prot = vma->vm_page_prot; pud_t entry; - spinlock_t *ptl; - ptl = pud_lock(mm, pud); if (!pud_none(*pud)) { if (write) { if (WARN_ON_ONCE(pud_pfn(*pud) != pfn_t_to_pfn(pfn))) - goto out_unlock; + return; entry = pud_mkyoung(*pud); entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); if (pudp_set_access_flags(vma, addr, pud, entry, 1)) update_mmu_cache_pud(vma, addr, pud); } - goto out_unlock; + return; } entry = pud_mkhuge(pfn_t_pud(pfn, prot)); @@ -1508,9 +1506,6 @@ static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, } set_pud_at(mm, addr, pud, entry); update_mmu_cache_pud(vma, addr, pud); - -out_unlock: - spin_unlock(ptl); } /** @@ -1528,6 +1523,7 @@ vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write) unsigned long addr = vmf->address & PUD_MASK; struct vm_area_struct *vma = vmf->vma; pgprot_t pgprot = vma->vm_page_prot; + spinlock_t *ptl; /* * If we had pud_special, we could avoid all these restrictions, @@ -1545,10 +1541,57 @@ vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write) track_pfn_insert(vma, &pgprot, pfn); + ptl = pud_lock(vma->vm_mm, vmf->pud); insert_pfn_pud(vma, addr, vmf->pud, pfn, write); + spin_unlock(ptl); + return VM_FAULT_NOPAGE; } EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud); + +/** + * vmf_insert_folio_pud - insert a pud size folio mapped by a pud entry + * @vmf: Structure describing the fault + * @folio: folio to insert + * @write: whether it's a write fault + * + * Return: vm_fault_t value. + */ +vm_fault_t vmf_insert_folio_pud(struct vm_fault *vmf, struct folio *folio, + bool write) +{ + struct vm_area_struct *vma = vmf->vma; + unsigned long addr = vmf->address & PUD_MASK; + pud_t *pud = vmf->pud; + struct mm_struct *mm = vma->vm_mm; + spinlock_t *ptl; + + if (addr < vma->vm_start || addr >= vma->vm_end) + return VM_FAULT_SIGBUS; + + if (WARN_ON_ONCE(folio_order(folio) != PUD_ORDER)) + return VM_FAULT_SIGBUS; + + ptl = pud_lock(mm, pud); + + /* + * If there is already an entry present we assume the folio is + * already mapped, hence no need to take another reference. We + * still call insert_pfn_pud() though in case the mapping needs + * upgrading to writeable. + */ + if (pud_none(*vmf->pud)) { + folio_get(folio); + folio_add_file_rmap_pud(folio, &folio->page, vma); + add_mm_counter(mm, mm_counter_file(folio), HPAGE_PUD_NR); + } + insert_pfn_pud(vma, addr, vmf->pud, pfn_to_pfn_t(folio_pfn(folio)), + write); + spin_unlock(ptl); + + return VM_FAULT_NOPAGE; +} +EXPORT_SYMBOL_GPL(vmf_insert_folio_pud); #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ void touch_pmd(struct vm_area_struct *vma, unsigned long addr, @@ -2146,7 +2189,8 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, zap_deposited_table(tlb->mm, pmd); spin_unlock(ptl); } else if (is_huge_zero_pmd(orig_pmd)) { - zap_deposited_table(tlb->mm, pmd); + if (!vma_is_dax(vma) || arch_needs_pgtable_deposit()) + zap_deposited_table(tlb->mm, pmd); spin_unlock(ptl); } else { struct folio *folio = NULL; @@ -2646,12 +2690,24 @@ int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, orig_pud = pudp_huge_get_and_clear_full(vma, addr, pud, tlb->fullmm); arch_check_zapped_pud(vma, orig_pud); tlb_remove_pud_tlb_entry(tlb, pud, addr); - if (vma_is_special_huge(vma)) { + if (!vma_is_dax(vma) && vma_is_special_huge(vma)) { spin_unlock(ptl); /* No zero page support yet */ } else { - /* No support for anonymous PUD pages yet */ - BUG(); + struct page *page = NULL; + struct folio *folio; + + /* No support for anonymous PUD pages or migration yet */ + VM_WARN_ON_ONCE(vma_is_anonymous(vma) || + !pud_present(orig_pud)); + + page = pud_page(orig_pud); + folio = page_folio(page); + folio_remove_rmap_pud(folio, page, vma); + add_mm_counter(tlb->mm, mm_counter_file(folio), -HPAGE_PUD_NR); + + spin_unlock(ptl); + tlb_remove_page_size(tlb, page, HPAGE_PUD_SIZE); } return 1; } @@ -2659,6 +2715,10 @@ int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, unsigned long haddr) { + struct folio *folio; + struct page *page; + pud_t old_pud; + VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); VM_BUG_ON_VMA(vma->vm_start > haddr, vma); VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); @@ -2666,7 +2726,22 @@ static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, count_vm_event(THP_SPLIT_PUD); - pudp_huge_clear_flush(vma, haddr, pud); + 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); + folio_remove_rmap_pud(folio, page, vma); + folio_put(folio); + add_mm_counter(vma->vm_mm, mm_counter_file(folio), + -HPAGE_PUD_NR); } void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,