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Fri, 30 Aug 2024 01:42:14 -0700 (PDT) From: Dev Jain To: akpm@linux-foundation.org, david@redhat.com, willy@infradead.org, kirill.shutemov@linux.intel.com Cc: ryan.roberts@arm.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, cl@gentwo.org, vbabka@suse.cz, mhocko@suse.com, apopple@nvidia.com, dave.hansen@linux.intel.com, will@kernel.org, baohua@kernel.org, jack@suse.cz, mark.rutland@arm.com, hughd@google.com, aneesh.kumar@kernel.org, yang@os.amperecomputing.com, peterx@redhat.com, ioworker0@gmail.com, jglisse@google.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Dev Jain Subject: [PATCH 2/2] mm: Allocate THP on hugezeropage wp-fault Date: Fri, 30 Aug 2024 14:11:17 +0530 Message-Id: <20240830084117.4079805-3-dev.jain@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240830084117.4079805-1-dev.jain@arm.com> References: <20240830084117.4079805-1-dev.jain@arm.com> MIME-Version: 1.0 X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: 342B3C0016 X-Stat-Signature: 5eb7nxmpqm5q9qegrnu4b15t4thh3oc1 X-HE-Tag: 1725007343-358606 X-HE-Meta: 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 8iF3WtqV tcpyTMV6UgALM4ALsxaS3E1b00ZwmSFoprlx2BI2RRiKkL6BKJ/5LvZh42ku150y9PvuKxosdYogkcqlz1ZLXCnOpQuBAw8ZVWfeVqH3ayfhH5aD3hx4wKUmlbi5gncMXSZ67LGEoo3tVK2jikMQy3KmElw== 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: List-Subscribe: List-Unsubscribe: Introduce do_huge_zero_wp_pmd() to handle wp-fault on a hugezeropage and replace it with a PMD-mapped THP. Change the helpers introduced in the previous patch to flush TLB entry corresponding to the hugezeropage, and preserve PMD uffd-wp marker. In case of failure, fallback to splitting the PMD. Signed-off-by: Dev Jain --- include/linux/huge_mm.h | 7 ++++ mm/huge_memory.c | 76 +++++++++++++++++++++++++++++++++++------ mm/memory.c | 5 +-- 3 files changed, 76 insertions(+), 12 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index e25d9ebfdf89..375dba4fb130 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -9,6 +9,13 @@ #include vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf); +vm_fault_t thp_fault_alloc(gfp_t gfp, int order, struct vm_area_struct *vma, + unsigned long haddr, struct folio **foliop, + unsigned long addr); +void map_pmd_thp(struct folio *folio, struct vm_fault *vmf, + struct vm_area_struct *vma, unsigned long haddr, + pgtable_t pgtable) + __releases(vmf->ptl); int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma); diff --git a/mm/huge_memory.c b/mm/huge_memory.c index e5b568e2bb34..0f8b2e224795 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -943,9 +943,9 @@ unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, } EXPORT_SYMBOL_GPL(thp_get_unmapped_area); -static vm_fault_t thp_fault_alloc(gfp_t gfp, int order, struct vm_area_struct *vma, - unsigned long haddr, struct folio **foliop, - unsigned long addr) +vm_fault_t thp_fault_alloc(gfp_t gfp, int order, struct vm_area_struct *vma, + unsigned long haddr, struct folio **foliop, + unsigned long addr) { struct folio *folio = vma_alloc_folio(gfp, order, vma, haddr, true); @@ -984,22 +984,30 @@ static void __thp_fault_success_stats(struct vm_area_struct *vma, int order) count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC); } -static void map_pmd_thp(struct folio *folio, struct vm_fault *vmf, - struct vm_area_struct *vma, unsigned long haddr, - pgtable_t pgtable) +void map_pmd_thp(struct folio *folio, struct vm_fault *vmf, + struct vm_area_struct *vma, unsigned long haddr, + pgtable_t pgtable) __releases(vmf->ptl) { - pmd_t entry; + pmd_t entry, old_pmd; + bool is_pmd_none = pmd_none(*vmf->pmd); entry = mk_huge_pmd(&folio->page, vma->vm_page_prot); entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); folio_add_new_anon_rmap(folio, vma, haddr, RMAP_EXCLUSIVE); folio_add_lru_vma(folio, vma); - pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); + if (!is_pmd_none) { + old_pmd = pmdp_huge_clear_flush(vma, haddr, vmf->pmd); + if (pmd_uffd_wp(old_pmd)) + entry = pmd_mkuffd_wp(entry); + } + if (pgtable) + pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); - mm_inc_nr_ptes(vma->vm_mm); + if (is_pmd_none) + mm_inc_nr_ptes(vma->vm_mm); spin_unlock(vmf->ptl); __thp_fault_success_stats(vma, HPAGE_PMD_ORDER); } @@ -1577,6 +1585,47 @@ void huge_pmd_set_accessed(struct vm_fault *vmf) spin_unlock(vmf->ptl); } +static vm_fault_t do_huge_zero_wp_pmd_locked(struct vm_fault *vmf, + unsigned long haddr) +{ + struct vm_area_struct *vma = vmf->vma; + gfp_t gfp = vma_thp_gfp_mask(vma); + struct folio *folio = NULL; + vm_fault_t ret; + + ret = thp_fault_alloc(gfp, HPAGE_PMD_ORDER, vma, haddr, &folio, + vmf->address); + if (ret) + goto unlock; + ret = check_stable_address_space(vma->vm_mm); + if (ret) + goto unlock; + map_pmd_thp(folio, vmf, vma, haddr, NULL); + return 0; + +unlock: + spin_unlock(vmf->ptl); + return ret; +} + +static vm_fault_t do_huge_zero_wp_pmd(struct vm_fault *vmf, unsigned long haddr) +{ + struct vm_area_struct *vma = vmf->vma; + struct mmu_notifier_range range; + vm_fault_t ret = 0; + + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, haddr, + haddr + HPAGE_PMD_SIZE); + mmu_notifier_invalidate_range_start(&range); + vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); + if (likely(pmd_same(pmdp_get(vmf->pmd), vmf->orig_pmd))) + ret = do_huge_zero_wp_pmd_locked(vmf, haddr); + else + spin_unlock(vmf->ptl); + mmu_notifier_invalidate_range_end(&range); + return ret; +} + vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) { const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; @@ -1589,8 +1638,15 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); VM_BUG_ON_VMA(!vma->anon_vma, vma); - if (is_huge_zero_pmd(orig_pmd)) + if (is_huge_zero_pmd(orig_pmd)) { + vm_fault_t ret = do_huge_zero_wp_pmd(vmf, haddr); + + if (!(ret & VM_FAULT_FALLBACK)) + return ret; + + /* Fallback to splitting PMD if THP cannot be allocated */ goto fallback; + } spin_lock(vmf->ptl); diff --git a/mm/memory.c b/mm/memory.c index 3c01d68065be..c081a25f5173 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5409,9 +5409,10 @@ static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf) if (vma_is_anonymous(vma)) { if (likely(!unshare) && userfaultfd_huge_pmd_wp(vma, vmf->orig_pmd)) { - if (userfaultfd_wp_async(vmf->vma)) + if (!userfaultfd_wp_async(vmf->vma)) + return handle_userfault(vmf, VM_UFFD_WP); + if (!is_huge_zero_pmd(vmf->orig_pmd)) goto split; - return handle_userfault(vmf, VM_UFFD_WP); } return do_huge_pmd_wp_page(vmf); }