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Wed, 11 Mar 2026 21:15:36 +0000 (UTC) Received: from h1.redhat.com (unknown [10.22.89.69]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 2D71D3002D0E; Wed, 11 Mar 2026 21:15:23 +0000 (UTC) From: Nico Pache To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: aarcange@redhat.com, akpm@linux-foundation.org, anshuman.khandual@arm.com, apopple@nvidia.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, byungchul@sk.com, catalin.marinas@arm.com, cl@gentwo.org, corbet@lwn.net, dave.hansen@linux.intel.com, david@kernel.org, dev.jain@arm.com, gourry@gourry.net, hannes@cmpxchg.org, hughd@google.com, jackmanb@google.com, jack@suse.cz, jannh@google.com, jglisse@google.com, joshua.hahnjy@gmail.com, kas@kernel.org, lance.yang@linux.dev, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, mathieu.desnoyers@efficios.com, matthew.brost@intel.com, mhiramat@kernel.org, mhocko@suse.com, npache@redhat.com, peterx@redhat.com, pfalcato@suse.de, rakie.kim@sk.com, raquini@redhat.com, rdunlap@infradead.org, richard.weiyang@gmail.com, rientjes@google.com, rostedt@goodmis.org, rppt@kernel.org, ryan.roberts@arm.com, shivankg@amd.com, sunnanyong@huawei.com, surenb@google.com, thomas.hellstrom@linux.intel.com, tiwai@suse.de, usamaarif642@gmail.com, vbabka@suse.cz, vishal.moola@gmail.com, wangkefeng.wang@huawei.com, will@kernel.org, willy@infradead.org, yang@os.amperecomputing.com, ying.huang@linux.alibaba.com, ziy@nvidia.com, zokeefe@google.com Subject: [PATCH mm-unstable v3 1/5] mm: consolidate anonymous folio PTE mapping into helpers Date: Wed, 11 Mar 2026 15:13:11 -0600 Message-ID: <20260311211315.450947-2-npache@redhat.com> In-Reply-To: <20260311211315.450947-1-npache@redhat.com> References: <20260311211315.450947-1-npache@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 5sCbfVpNjRBGcbH0MO09hRGbCuKAEBGxRIUDQn6qilE_1773263738 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true X-Rspamd-Queue-Id: D5993A000C X-Stat-Signature: 8foqy8f4tkm4cw5a3d33jpa4d5t5f918 X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1773263748-878802 X-HE-Meta: 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 zId+R+lv 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The anonymous page fault handler in do_anonymous_page() open-codes the sequence to map a newly allocated anonymous folio at the PTE level: - construct the PTE entry - add rmap - add to LRU - set the PTEs - update the MMU cache. Introduce a two helpers to consolidate this duplicated logic, mirroring the existing map_anon_folio_pmd_nopf() pattern for PMD-level mappings: map_anon_folio_pte_nopf(): constructs the PTE entry, takes folio references, adds anon rmap and LRU. This function also handles the uffd_wp that can occur in the pf variant. map_anon_folio_pte_pf(): extends the nopf variant to handle MM_ANONPAGES counter updates, and mTHP fault allocation statistics for the page fault path. The zero-page read path in do_anonymous_page() is also untangled from the shared setpte label, since it does not allocate a folio and should not share the same mapping sequence as the write path. Make nr_pages = 1 rather than relying on the variable. This makes it more clear that we are operating on the zero page only. This refactoring will also help reduce code duplication between mm/memory.c and mm/khugepaged.c, and provides a clean API for PTE-level anonymous folio mapping that can be reused by future callers. Reviewed-by: Dev Jain Reviewed-by: Lance Yang Acked-by: David Hildenbrand (Arm) Signed-off-by: Nico Pache --- include/linux/mm.h | 4 ++++ mm/memory.c | 60 +++++++++++++++++++++++++++++++--------------- 2 files changed, 45 insertions(+), 19 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 4c4fd55fc823..9fea354bd17f 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4903,4 +4903,8 @@ static inline bool snapshot_page_is_faithful(const struct page_snapshot *ps) void snapshot_page(struct page_snapshot *ps, const struct page *page); +void map_anon_folio_pte_nopf(struct folio *folio, pte_t *pte, + struct vm_area_struct *vma, unsigned long addr, + bool uffd_wp); + #endif /* _LINUX_MM_H */ diff --git a/mm/memory.c b/mm/memory.c index 6aa0ea4af1fc..5c8bf1eb55f5 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5197,6 +5197,37 @@ static struct folio *alloc_anon_folio(struct vm_fault *vmf) return folio_prealloc(vma->vm_mm, vma, vmf->address, true); } +void map_anon_folio_pte_nopf(struct folio *folio, pte_t *pte, + struct vm_area_struct *vma, unsigned long addr, + bool uffd_wp) +{ + unsigned int nr_pages = folio_nr_pages(folio); + pte_t entry = folio_mk_pte(folio, vma->vm_page_prot); + + entry = pte_sw_mkyoung(entry); + + if (vma->vm_flags & VM_WRITE) + entry = pte_mkwrite(pte_mkdirty(entry), vma); + if (uffd_wp) + entry = pte_mkuffd_wp(entry); + + folio_ref_add(folio, nr_pages - 1); + folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE); + folio_add_lru_vma(folio, vma); + set_ptes(vma->vm_mm, addr, pte, entry, nr_pages); + update_mmu_cache_range(NULL, vma, addr, pte, nr_pages); +} + +static void map_anon_folio_pte_pf(struct folio *folio, pte_t *pte, + struct vm_area_struct *vma, unsigned long addr, bool uffd_wp) +{ + unsigned int order = folio_order(folio); + + map_anon_folio_pte_nopf(folio, pte, vma, addr, uffd_wp); + add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1 << order); + count_mthp_stat(order, MTHP_STAT_ANON_FAULT_ALLOC); +} + /* * We enter with non-exclusive mmap_lock (to exclude vma changes, * but allow concurrent faults), and pte mapped but not yet locked. @@ -5243,7 +5274,14 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf) pte_unmap_unlock(vmf->pte, vmf->ptl); return handle_userfault(vmf, VM_UFFD_MISSING); } - goto setpte; + if (vmf_orig_pte_uffd_wp(vmf)) + entry = pte_mkuffd_wp(entry); + set_pte_at(vma->vm_mm, addr, vmf->pte, entry); + + /* No need to invalidate - it was non-present before */ + update_mmu_cache_range(vmf, vma, addr, vmf->pte, + /*nr_pages=*/ 1); + goto unlock; } /* Allocate our own private page. */ @@ -5267,11 +5305,6 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf) */ __folio_mark_uptodate(folio); - entry = folio_mk_pte(folio, vma->vm_page_prot); - entry = pte_sw_mkyoung(entry); - if (vma->vm_flags & VM_WRITE) - entry = pte_mkwrite(pte_mkdirty(entry), vma); - vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, addr, &vmf->ptl); if (!vmf->pte) goto release; @@ -5293,19 +5326,8 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf) folio_put(folio); return handle_userfault(vmf, VM_UFFD_MISSING); } - - folio_ref_add(folio, nr_pages - 1); - add_mm_counter(vma->vm_mm, MM_ANONPAGES, nr_pages); - count_mthp_stat(folio_order(folio), MTHP_STAT_ANON_FAULT_ALLOC); - folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE); - folio_add_lru_vma(folio, vma); -setpte: - if (vmf_orig_pte_uffd_wp(vmf)) - entry = pte_mkuffd_wp(entry); - set_ptes(vma->vm_mm, addr, vmf->pte, entry, nr_pages); - - /* No need to invalidate - it was non-present before */ - update_mmu_cache_range(vmf, vma, addr, vmf->pte, nr_pages); + map_anon_folio_pte_pf(folio, vmf->pte, vma, addr, + vmf_orig_pte_uffd_wp(vmf)); unlock: if (vmf->pte) pte_unmap_unlock(vmf->pte, vmf->ptl); -- 2.53.0