From: Baolin Wang Date: Fri, 5 Jun 2026 16:14:20 +0000 (-0600) Subject: mm/khugepaged: run khugepaged for all orders X-Git-Tag: v7.2-rc1~59^2~100 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b7f16963efe73502dc3e27c4ca15c8e687fd37bc;p=thirdparty%2Fkernel%2Flinux.git mm/khugepaged: run khugepaged for all orders If any order (m)THP is enabled we should allow running khugepaged to attempt scanning and collapsing mTHPs. In order for khugepaged to operate when only mTHP sizes are specified in sysfs, we must modify the predicate function that determines whether it ought to run to do so. This function is currently called hugepage_pmd_enabled(), this patch renames it to hugepage_enabled() and updates the logic to check to determine whether any valid orders may exist which would justify khugepaged running. We must also update collapse_possible_orders() to check all orders if the vma is anonymous and the collapse is khugepaged. After this patch khugepaged mTHP collapse is fully enabled. Link: https://lore.kernel.org/20260605161422.213817-14-npache@redhat.com Signed-off-by: Baolin Wang Signed-off-by: Nico Pache Reviewed-by: Lorenzo Stoakes Reviewed-by: Lance Yang Acked-by: Usama Arif Acked-by: David Hildenbrand (Arm) Cc: Alistair Popple Cc: Andrea Arcangeli Cc: Anshuman Khandual Cc: Bagas Sanjaya Cc: Barry Song Cc: Brendan Jackman Cc: Byungchul Park Cc: Catalin Marinas Cc: David Rientjes Cc: Dev Jain 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 R. 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 Signed-off-by: Andrew Morton --- diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 5a2adbdbd0557..6de1a148222a0 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -503,23 +503,23 @@ static inline int collapse_test_exit_or_disable(struct mm_struct *mm) mm_flags_test(MMF_DISABLE_THP_COMPLETELY, mm); } -static bool hugepage_pmd_enabled(void) +static bool hugepage_enabled(void) { /* * We cover the anon, shmem and the file-backed case here; file-backed * hugepages, when configured in, are determined by the global control. - * Anon pmd-sized hugepages are determined by the pmd-size control. + * Anon hugepages are determined by its per-size mTHP control. * Shmem pmd-sized hugepages are also determined by its pmd-size control, * except when the global shmem_huge is set to SHMEM_HUGE_DENY. */ if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && hugepage_global_enabled()) return true; - if (test_bit(PMD_ORDER, &huge_anon_orders_always)) + if (READ_ONCE(huge_anon_orders_always)) return true; - if (test_bit(PMD_ORDER, &huge_anon_orders_madvise)) + if (READ_ONCE(huge_anon_orders_madvise)) return true; - if (test_bit(PMD_ORDER, &huge_anon_orders_inherit) && + if (READ_ONCE(huge_anon_orders_inherit) && hugepage_global_enabled()) return true; if (IS_ENABLED(CONFIG_SHMEM) && shmem_hpage_pmd_enabled()) @@ -566,7 +566,13 @@ void __khugepaged_enter(struct mm_struct *mm) static unsigned long collapse_possible_orders(struct vm_area_struct *vma, vm_flags_t vm_flags, enum tva_type tva_flags) { - const unsigned long orders = BIT(HPAGE_PMD_ORDER); + unsigned long orders; + + /* If khugepaged is scanning an anonymous vma, allow mTHP collapse */ + if ((tva_flags == TVA_KHUGEPAGED) && vma_is_anonymous(vma)) + orders = THP_ORDERS_ALL_ANON; + else + orders = BIT(HPAGE_PMD_ORDER); return thp_vma_allowable_orders(vma, vm_flags, tva_flags, orders); } @@ -580,11 +586,9 @@ static bool collapse_possible(struct vm_area_struct *vma, void khugepaged_enter_vma(struct vm_area_struct *vma, vm_flags_t vm_flags) { - if (!mm_flags_test(MMF_VM_HUGEPAGE, vma->vm_mm) && - hugepage_pmd_enabled()) { - if (collapse_possible(vma, vm_flags, TVA_KHUGEPAGED)) - __khugepaged_enter(vma->vm_mm); - } + if (!mm_flags_test(MMF_VM_HUGEPAGE, vma->vm_mm) && hugepage_enabled() + && collapse_possible(vma, vm_flags, TVA_KHUGEPAGED)) + __khugepaged_enter(vma->vm_mm); } void __khugepaged_exit(struct mm_struct *mm) @@ -2941,7 +2945,7 @@ breakouterloop_mmap_lock: static int khugepaged_has_work(void) { - return !list_empty(&khugepaged_scan.mm_head) && hugepage_pmd_enabled(); + return !list_empty(&khugepaged_scan.mm_head) && hugepage_enabled(); } static int khugepaged_wait_event(void) @@ -3014,7 +3018,7 @@ static void khugepaged_wait_work(void) return; } - if (hugepage_pmd_enabled()) + if (hugepage_enabled()) wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); } @@ -3045,7 +3049,7 @@ void set_recommended_min_free_kbytes(void) int nr_zones = 0; unsigned long recommended_min; - if (!hugepage_pmd_enabled()) { + if (!hugepage_enabled()) { calculate_min_free_kbytes(); goto update_wmarks; } @@ -3095,7 +3099,7 @@ int start_stop_khugepaged(void) int err = 0; mutex_lock(&khugepaged_mutex); - if (hugepage_pmd_enabled()) { + if (hugepage_enabled()) { if (!khugepaged_thread) khugepaged_thread = kthread_run(khugepaged, NULL, "khugepaged"); @@ -3121,7 +3125,7 @@ fail: void khugepaged_min_free_kbytes_update(void) { mutex_lock(&khugepaged_mutex); - if (hugepage_pmd_enabled() && khugepaged_thread) + if (hugepage_enabled() && khugepaged_thread) set_recommended_min_free_kbytes(); mutex_unlock(&khugepaged_mutex); }