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Message-ID: <b1c1e92f29094d6d5b78c6f87dc8ac81a9cbd7aa.1734407924.git-series.apopple@nvidia.com> Date: Tue, 17 Dec 2024 16:12:59 +1100 From: Alistair Popple <apopple@...dia.com> To: akpm@...ux-foundation.org, dan.j.williams@...el.com, linux-mm@...ck.org Cc: Alistair Popple <apopple@...dia.com>, lina@...hilina.net, zhang.lyra@...il.com, gerald.schaefer@...ux.ibm.com, vishal.l.verma@...el.com, dave.jiang@...el.com, logang@...tatee.com, bhelgaas@...gle.com, jack@...e.cz, jgg@...pe.ca, catalin.marinas@....com, will@...nel.org, mpe@...erman.id.au, npiggin@...il.com, dave.hansen@...ux.intel.com, ira.weiny@...el.com, willy@...radead.org, djwong@...nel.org, tytso@....edu, linmiaohe@...wei.com, david@...hat.com, peterx@...hat.com, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org, nvdimm@...ts.linux.dev, linux-cxl@...r.kernel.org, linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org, jhubbard@...dia.com, hch@....de, david@...morbit.com Subject: [PATCH v4 16/25] huge_memory: Add vmf_insert_folio_pmd() 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_pmd. This will map the entire PMD-sized folio and take references as it would for a normally mapped page. This is distinct from the current mechanism, vmf_insert_pfn_pmd, which simply inserts a special devmap PMD entry into the page table without holding a reference to the page for the mapping. Signed-off-by: Alistair Popple <apopple@...dia.com> --- include/linux/huge_mm.h | 1 +- mm/huge_memory.c | 60 +++++++++++++++++++++++++++++++++++------- 2 files changed, 51 insertions(+), 10 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 012137b..4ad9aa7 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -39,6 +39,7 @@ 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_pmd(struct vm_fault *vmf, struct folio *folio, bool write); vm_fault_t vmf_insert_folio_pud(struct vm_fault *vmf, struct folio *folio, bool write); enum transparent_hugepage_flag { diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 5081808..55293b0 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1381,14 +1381,12 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, { struct mm_struct *mm = vma->vm_mm; pmd_t entry; - spinlock_t *ptl; - ptl = pmd_lock(mm, pmd); if (!pmd_none(*pmd)) { if (write) { if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) { WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); - goto out_unlock; + return; } entry = pmd_mkyoung(*pmd); entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); @@ -1396,7 +1394,7 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, update_mmu_cache_pmd(vma, addr, pmd); } - goto out_unlock; + return; } entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); @@ -1417,11 +1415,6 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, set_pmd_at(mm, addr, pmd, entry); update_mmu_cache_pmd(vma, addr, pmd); - -out_unlock: - spin_unlock(ptl); - if (pgtable) - pte_free(mm, pgtable); } /** @@ -1440,6 +1433,7 @@ vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write) struct vm_area_struct *vma = vmf->vma; pgprot_t pgprot = vma->vm_page_prot; pgtable_t pgtable = NULL; + spinlock_t *ptl; /* * If we had pmd_special, we could avoid all these restrictions, @@ -1462,12 +1456,58 @@ vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write) } track_pfn_insert(vma, &pgprot, pfn); - + ptl = pmd_lock(vma->vm_mm, vmf->pmd); insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable); + spin_unlock(ptl); + if (pgtable) + pte_free(vma->vm_mm, pgtable); + return VM_FAULT_NOPAGE; } EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); +vm_fault_t vmf_insert_folio_pmd(struct vm_fault *vmf, struct folio *folio, bool write) +{ + struct vm_area_struct *vma = vmf->vma; + unsigned long addr = vmf->address & PMD_MASK; + pfn_t pfn = pfn_to_pfn_t(folio_pfn(folio)); + struct mm_struct *mm = vma->vm_mm; + spinlock_t *ptl; + pgtable_t pgtable = NULL; + struct page *page; + + if (addr < vma->vm_start || addr >= vma->vm_end) + return VM_FAULT_SIGBUS; + + if (WARN_ON_ONCE(folio_order(folio) != PMD_ORDER)) + return VM_FAULT_SIGBUS; + + if (arch_needs_pgtable_deposit()) { + pgtable = pte_alloc_one(vma->vm_mm); + if (!pgtable) + return VM_FAULT_OOM; + } + + track_pfn_insert(vma, &vma->vm_page_prot, pfn); + + ptl = pmd_lock(mm, vmf->pmd); + if (pmd_none(*vmf->pmd)) { + page = pfn_t_to_page(pfn); + folio = page_folio(page); + folio_get(folio); + folio_add_file_rmap_pmd(folio, page, vma); + add_mm_counter(mm, mm_counter_file(folio), HPAGE_PMD_NR); + } + insert_pfn_pmd(vma, addr, vmf->pmd, pfn, vma->vm_page_prot, + write, pgtable); + spin_unlock(ptl); + if (pgtable) + pte_free(mm, pgtable); + + return VM_FAULT_NOPAGE; +} +EXPORT_SYMBOL_GPL(vmf_insert_folio_pmd); + #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) { -- git-series 0.9.1
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