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Elide the overhead of vm_normal_folio() for the small folio case, by making an approximation: for arm64, pte_batch_hint() is conclusive. For other arches, if the pfns pointed to by the current and the next PTE are contiguous, check whether a large folio is actually mapped, and only then make the batch optimization. Reuse the folio from prot_numa case if possible. Since modify_prot_start_ptes() gathers access/dirty bits, it lets us batch around pte_needs_flush() (for parisc, the definition includes the access bit). Signed-off-by: Dev Jain --- mm/mprotect.c | 49 +++++++++++++++++++++++++++++++++++-------------- 1 file changed, 35 insertions(+), 14 deletions(-) diff --git a/mm/mprotect.c b/mm/mprotect.c index 362fd7e5457d..d382d57bc796 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -131,7 +131,7 @@ static bool prot_numa_skip(struct vm_area_struct *vma, struct folio *folio, return false; } -static bool prot_numa_avoid_fault(struct vm_area_struct *vma, +static struct folio *prot_numa_avoid_fault(struct vm_area_struct *vma, unsigned long addr, pte_t *pte, pte_t oldpte, int target_node, int max_nr, int *nr) { @@ -141,25 +141,37 @@ static bool prot_numa_avoid_fault(struct vm_area_struct *vma, /* Avoid TLB flush if possible */ if (pte_protnone(oldpte)) - return true; + return NULL; folio = vm_normal_folio(vma, addr, oldpte); if (!folio) - return true; + return NULL; ret = prot_numa_skip(vma, folio, target_node); if (ret) { if (folio_test_large(folio) && max_nr != 1) *nr = folio_pte_batch(folio, addr, pte, oldpte, max_nr, flags, NULL, NULL, NULL); - return ret; + return NULL; } if (folio_use_access_time(folio)) folio_xchg_access_time(folio, jiffies_to_msecs(jiffies)); - return false; + return folio; } +static bool maybe_contiguous_pte_pfns(pte_t *ptep, pte_t pte) +{ + pte_t *next_ptep, next_pte; + + if (pte_batch_hint(ptep, pte) != 1) + return true; + + next_ptep = ptep + 1; + next_pte = ptep_get(next_ptep); + + return unlikely(pte_pfn(next_pte) - pte_pfn(pte) == PAGE_SIZE); +} 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) @@ -190,19 +202,28 @@ static long change_pte_range(struct mmu_gather *tlb, oldpte = ptep_get(pte); if (pte_present(oldpte)) { int max_nr = (end - addr) >> PAGE_SHIFT; + const fpb_t flags = FPB_IGNORE_DIRTY; + struct folio *folio = NULL; pte_t ptent; /* * Avoid trapping faults against the zero or KSM * pages. See similar comment in change_huge_pmd. */ - if (prot_numa && - prot_numa_avoid_fault(vma, addr, pte, - oldpte, target_node, - max_nr, &nr)) + if (prot_numa) { + folio = prot_numa_avoid_fault(vma, addr, pte, + oldpte, target_node, max_nr, &nr); + if (!folio) continue; + } - oldpte = ptep_modify_prot_start(vma, addr, pte); + if (!folio && (max_nr != 1) && maybe_contiguous_pte_pfns(pte, oldpte)) { + folio = vm_normal_folio(vma, addr, oldpte); + if (folio_test_large(folio)) + nr = folio_pte_batch(folio, addr, pte, + oldpte, max_nr, flags, NULL, NULL, NULL); + } + oldpte = modify_prot_start_ptes(vma, addr, pte, nr); ptent = pte_modify(oldpte, newprot); if (uffd_wp) @@ -225,13 +246,13 @@ static long change_pte_range(struct mmu_gather *tlb, */ if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && !pte_write(ptent) && - can_change_ptes_writable(vma, addr, ptent, folio, 1)) + can_change_ptes_writable(vma, addr, ptent, folio, nr)) ptent = pte_mkwrite(ptent, vma); - ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent); + modify_prot_commit_ptes(vma, addr, pte, oldpte, ptent, nr); if (pte_needs_flush(oldpte, ptent)) - tlb_flush_pte_range(tlb, addr, PAGE_SIZE); - pages++; + tlb_flush_pte_range(tlb, addr, nr * PAGE_SIZE); + pages += nr; } else if (is_swap_pte(oldpte)) { swp_entry_t entry = pte_to_swp_entry(oldpte); pte_t newpte; -- 2.30.2