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Fri, 30 Aug 2024 01:42:05 -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 1/2] mm: Abstract THP allocation Date: Fri, 30 Aug 2024 14:11:16 +0530 Message-Id: <20240830084117.4079805-2-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-Rspam-User: X-Rspamd-Queue-Id: 671DAA0002 X-Rspamd-Server: rspam01 X-Stat-Signature: maebsqj1fuihhwdnhektfx5ztwtkanpe X-HE-Tag: 1725007335-116124 X-HE-Meta: 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 z+yXMJ9f 1tXkIGjwVuia3YMwnvAINcfwQ6Dp7RtDfJ6R8MMrzThdkV6n/SLJSOzD+VhAtqFD5OQYqfz+pIn3SHwG2u/O6TcLAA8zDqL7g/QrH8tHn2VMaSlussn3Sr5Q0fiQUlXxCLQBenZ56jGpudUsxAzMXeUIULA== 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: In preparation for the second patch, abstract away the THP allocation logic present in the create_huge_pmd() path, which corresponds to the faulting case when no page is present. There should be no functional change as a result of applying this patch. Signed-off-by: Dev Jain --- mm/huge_memory.c | 113 +++++++++++++++++++++++++++++------------------ 1 file changed, 69 insertions(+), 44 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 67c86a5d64a6..e5b568e2bb34 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -943,47 +943,92 @@ unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, } EXPORT_SYMBOL_GPL(thp_get_unmapped_area); -static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, - struct page *page, gfp_t gfp) +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) { - struct vm_area_struct *vma = vmf->vma; - struct folio *folio = page_folio(page); - pgtable_t pgtable; - unsigned long haddr = vmf->address & HPAGE_PMD_MASK; - vm_fault_t ret = 0; + struct folio *folio = vma_alloc_folio(gfp, order, vma, haddr, true); - VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); + *foliop = folio; + if (unlikely(!folio)) { + count_vm_event(THP_FAULT_FALLBACK); + count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK); + return VM_FAULT_FALLBACK; + } + VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); if (mem_cgroup_charge(folio, vma->vm_mm, gfp)) { folio_put(folio); count_vm_event(THP_FAULT_FALLBACK); count_vm_event(THP_FAULT_FALLBACK_CHARGE); - count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_FALLBACK); - count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE); + count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK); + count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE); return VM_FAULT_FALLBACK; } folio_throttle_swaprate(folio, gfp); - pgtable = pte_alloc_one(vma->vm_mm); - if (unlikely(!pgtable)) { - ret = VM_FAULT_OOM; - goto release; - } - - folio_zero_user(folio, vmf->address); + folio_zero_user(folio, addr); /* * The memory barrier inside __folio_mark_uptodate makes sure that * folio_zero_user writes become visible before the set_pmd_at() * write. */ __folio_mark_uptodate(folio); + return 0; +} + +static void __thp_fault_success_stats(struct vm_area_struct *vma, int order) +{ + count_vm_event(THP_FAULT_ALLOC); + count_mthp_stat(order, MTHP_STAT_ANON_FAULT_ALLOC); + 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) + __releases(vmf->ptl) +{ + pmd_t entry; + + 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); + 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); + spin_unlock(vmf->ptl); + __thp_fault_success_stats(vma, HPAGE_PMD_ORDER); +} + +static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf) +{ + struct vm_area_struct *vma = vmf->vma; + struct folio *folio = NULL; + pgtable_t pgtable; + unsigned long haddr = vmf->address & HPAGE_PMD_MASK; + vm_fault_t ret = 0; + gfp_t gfp = vma_thp_gfp_mask(vma); + + pgtable = pte_alloc_one(vma->vm_mm); + if (unlikely(!pgtable)) { + ret = VM_FAULT_OOM; + goto release; + } + + ret = thp_fault_alloc(gfp, HPAGE_PMD_ORDER, vma, haddr, &folio, + vmf->address); + if (ret) + goto release; vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); + if (unlikely(!pmd_none(*vmf->pmd))) { goto unlock_release; } else { - pmd_t entry; - ret = check_stable_address_space(vma->vm_mm); if (ret) goto unlock_release; @@ -997,20 +1042,7 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, VM_BUG_ON(ret & VM_FAULT_FALLBACK); return ret; } - - entry = mk_huge_pmd(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); - 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); - spin_unlock(vmf->ptl); - count_vm_event(THP_FAULT_ALLOC); - count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC); - count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC); + map_pmd_thp(folio, vmf, vma, haddr, pgtable); } return 0; @@ -1019,7 +1051,8 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, release: if (pgtable) pte_free(vma->vm_mm, pgtable); - folio_put(folio); + if (folio) + folio_put(folio); return ret; } @@ -1077,8 +1110,6 @@ static void set_huge_zero_folio(pgtable_t pgtable, struct mm_struct *mm, vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) { struct vm_area_struct *vma = vmf->vma; - gfp_t gfp; - struct folio *folio; unsigned long haddr = vmf->address & HPAGE_PMD_MASK; vm_fault_t ret; @@ -1129,14 +1160,8 @@ vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) } return ret; } - gfp = vma_thp_gfp_mask(vma); - folio = vma_alloc_folio(gfp, HPAGE_PMD_ORDER, vma, haddr, true); - if (unlikely(!folio)) { - count_vm_event(THP_FAULT_FALLBACK); - count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_FALLBACK); - return VM_FAULT_FALLBACK; - } - return __do_huge_pmd_anonymous_page(vmf, &folio->page, gfp); + + return __do_huge_pmd_anonymous_page(vmf); } static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, From patchwork Fri Aug 30 08:41:17 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dev Jain X-Patchwork-Id: 13784561 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id E83BBCA0EF5 for ; Fri, 30 Aug 2024 08:42:26 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 585CE6B00D8; Fri, 30 Aug 2024 04:42:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 532EA6B00D9; 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Fri, 30 Aug 2024 01:42:49 -0700 (PDT) Received: from e116581.blr.arm.com (e116581.arm.com [10.162.40.24]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 0DE073F762; 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); }