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Since the skip condition is based on the folio and not the PTEs, we can skip a PTE batch. Additionally refactor all of this into a new function to clean up the existing code. Signed-off-by: Dev Jain --- mm/mprotect.c | 134 ++++++++++++++++++++++++++++++++------------------ 1 file changed, 87 insertions(+), 47 deletions(-) diff --git a/mm/mprotect.c b/mm/mprotect.c index 88709c01177b..af10a7fbe6b8 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -83,6 +83,83 @@ bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr, return pte_dirty(pte); } +static int mprotect_folio_pte_batch(struct folio *folio, unsigned long addr, + pte_t *ptep, pte_t pte, int max_nr_ptes) +{ + const fpb_t flags = FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY; + + if (!folio || !folio_test_large(folio) || (max_nr_ptes == 1)) + return 1; + + return folio_pte_batch(folio, addr, ptep, pte, max_nr_ptes, flags, + NULL, NULL, NULL); +} + +static int prot_numa_skip_ptes(struct folio **foliop, struct vm_area_struct *vma, + unsigned long addr, pte_t oldpte, pte_t *pte, int target_node, + int max_nr_ptes) +{ + struct folio *folio = NULL; + int nr_ptes = 1; + bool toptier; + int nid; + + /* Avoid TLB flush if possible */ + if (pte_protnone(oldpte)) + goto skip_batch; + + folio = vm_normal_folio(vma, addr, oldpte); + if (!folio) + goto skip_batch; + + if (folio_is_zone_device(folio) || folio_test_ksm(folio)) + goto skip_batch; + + /* Also skip shared copy-on-write pages */ + if (is_cow_mapping(vma->vm_flags) && + (folio_maybe_dma_pinned(folio) || folio_maybe_mapped_shared(folio))) + goto skip_batch; + + /* + * While migration can move some dirty pages, + * it cannot move them all from MIGRATE_ASYNC + * context. + */ + if (folio_is_file_lru(folio) && folio_test_dirty(folio)) + goto skip_batch; + + /* + * Don't mess with PTEs if page is already on the node + * a single-threaded process is running on. + */ + nid = folio_nid(folio); + if (target_node == nid) + goto skip_batch; + + toptier = node_is_toptier(nid); + + /* + * Skip scanning top tier node if normal numa + * balancing is disabled + */ + if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && toptier) + goto skip_batch; + + if (folio_use_access_time(folio)) { + folio_xchg_access_time(folio, jiffies_to_msecs(jiffies)); + + /* Do not skip in this case */ + nr_ptes = 0; + goto out; + } + +skip_batch: + nr_ptes = mprotect_folio_pte_batch(folio, addr, pte, oldpte, max_nr_ptes); +out: + *foliop = folio; + return nr_ptes; +} + static long change_pte_range(struct mmu_gather *tlb, struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, unsigned long end, pgprot_t newprot, unsigned long cp_flags) @@ -94,6 +171,7 @@ static long change_pte_range(struct mmu_gather *tlb, bool prot_numa = cp_flags & MM_CP_PROT_NUMA; bool uffd_wp = cp_flags & MM_CP_UFFD_WP; bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; + int nr_ptes; tlb_change_page_size(tlb, PAGE_SIZE); pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); @@ -108,8 +186,11 @@ static long change_pte_range(struct mmu_gather *tlb, flush_tlb_batched_pending(vma->vm_mm); arch_enter_lazy_mmu_mode(); do { + nr_ptes = 1; oldpte = ptep_get(pte); if (pte_present(oldpte)) { + int max_nr_ptes = (end - addr) >> PAGE_SHIFT; + struct folio *folio = NULL; pte_t ptent; /* @@ -117,53 +198,12 @@ static long change_pte_range(struct mmu_gather *tlb, * pages. See similar comment in change_huge_pmd. */ if (prot_numa) { - struct folio *folio; - int nid; - bool toptier; - - /* Avoid TLB flush if possible */ - if (pte_protnone(oldpte)) - continue; - - folio = vm_normal_folio(vma, addr, oldpte); - if (!folio || folio_is_zone_device(folio) || - folio_test_ksm(folio)) - continue; - - /* Also skip shared copy-on-write pages */ - if (is_cow_mapping(vma->vm_flags) && - (folio_maybe_dma_pinned(folio) || - folio_maybe_mapped_shared(folio))) - continue; - - /* - * While migration can move some dirty pages, - * it cannot move them all from MIGRATE_ASYNC - * context. - */ - if (folio_is_file_lru(folio) && - folio_test_dirty(folio)) - continue; - - /* - * Don't mess with PTEs if page is already on the node - * a single-threaded process is running on. - */ - nid = folio_nid(folio); - if (target_node == nid) - continue; - toptier = node_is_toptier(nid); - - /* - * Skip scanning top tier node if normal numa - * balancing is disabled - */ - if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && - toptier) + nr_ptes = prot_numa_skip_ptes(&folio, vma, + addr, oldpte, pte, + target_node, + max_nr_ptes); + if (nr_ptes) continue; - if (folio_use_access_time(folio)) - folio_xchg_access_time(folio, - jiffies_to_msecs(jiffies)); } oldpte = ptep_modify_prot_start(vma, addr, pte); @@ -280,7 +320,7 @@ static long change_pte_range(struct mmu_gather *tlb, pages++; } } - } while (pte++, addr += PAGE_SIZE, addr != end); + } while (pte += nr_ptes, addr += nr_ptes * PAGE_SIZE, addr != end); arch_leave_lazy_mmu_mode(); pte_unmap_unlock(pte - 1, ptl); -- 2.30.2