From a91fd9f710490a89713823be3e7790ac59a085f8 Mon Sep 17 00:00:00 2001 From: Nico Pache Date: Wed, 25 Mar 2026 05:40:18 -0600 Subject: mm: consolidate anonymous folio PTE mapping into helpers MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Patch series "mm: khugepaged cleanups and mTHP prerequisites", v4. The following series contains cleanups and prerequisites for my work on khugepaged mTHP support [1]. These have been separated out to ease review. The first patch in the series refactors the page fault folio to pte mapping and follows a similar convention as defined by map_anon_folio_pmd_(no)pf(). This not only cleans up the current implementation of do_anonymous_page(), but will allow for reuse later in the khugepaged mTHP implementation. The second patch adds a small is_pmd_order() helper to check if an order is the PMD order. This check is open-coded in a number of places. This patch aims to clean this up and will be used more in the khugepaged mTHP work. The third patch also adds a small DEFINE for (HPAGE_PMD_NR - 1) which is used often across the khugepaged code. The fourth and fifth patch come from the khugepaged mTHP patchset [1]. These two patches include the rename of function prefixes, and the unification of khugepaged and madvise_collapse via a new collapse_single_pmd function. Patch 1: refactor do_anonymous_page into map_anon_folio_pte_(no)pf Patch 2: add is_pmd_order helper Patch 3: Add define for (HPAGE_PMD_NR - 1) Patch 4: Refactor/rename hpage_collapse Patch 5: Refactoring to combine madvise_collapse and khugepaged A big thanks to everyone that has reviewed, tested, and participated in the development process. This patch (of 5): 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 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. The future khugepaged mTHP code calls this to handle mapping the new collapsed mTHP to its folio. 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. We can now leave nr_pages undeclared at the function intialization, and use the single page update_mmu_cache function to handle the zero page update. 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 (like khugpeaged mTHP support) Link: https://lkml.kernel.org/r/20260325114022.444081-1-npache@redhat.com Link: https://lkml.kernel.org/r/20260325114022.444081-2-npache@redhat.com Link: https://lore.kernel.org/all/20260122192841.128719-1-npache@redhat.com Signed-off-by: Nico Pache Suggested-by: Lorenzo Stoakes (Oracle) Reviewed-by: Lorenzo Stoakes (Oracle) Reviewed-by: Dev Jain Reviewed-by: Lance Yang Acked-by: David Hildenbrand (Arm) Cc: Alistair Popple Cc: Andrea Arcangeli Cc: Anshuman Khandual Cc: Baolin Wang Cc: Barry Song Cc: Brendan Jackman Cc: Byungchul Park Cc: Catalin Marinas Cc: David Rientjes Cc: Gregory Price Cc: "Huang, Ying" Cc: Hugh Dickins Cc: Jan Kara Cc: Jann Horn Cc: Johannes Weiner Cc: Jonathan Corbet Cc: Joshua Hahn Cc: Kefeng Wang Cc: Liam Howlett Cc: "Masami Hiramatsu (Google)" Cc: Mathieu Desnoyers Cc: Matthew Brost Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Mike Rapoport Cc: Nanyong Sun Cc: Pedro Falcato Cc: Peter Xu Cc: Rafael Aquini Cc: Rakie Kim Cc: Randy Dunlap Cc: Ryan Roberts Cc: Shivank Garg Cc: Steven Rostedt Cc: Suren Baghdasaryan Cc: Takashi Iwai (SUSE) Cc: Thomas Hellström Cc: Usama Arif Cc: Vishal Moola (Oracle) Cc: Vlastimil Babka Cc: Wei Yang Cc: Will Deacon Cc: Yang Shi Cc: Zach O'Keefe Cc: Zi Yan Cc: Lorenzo Stoakes Signed-off-by: Andrew Morton --- include/linux/mm.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include') diff --git a/include/linux/mm.h b/include/linux/mm.h index 25ba5816e02b..16a1ad9a3397 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4916,4 +4916,8 @@ 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 */ -- cgit v1.2.3