On Fri, Oct 30, 2015 at 04:01:37PM +0900, Minchan Kim wrote: > +static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, > + unsigned long end, struct mm_walk *walk) > + > +{ > + struct mmu_gather *tlb = walk->private; > + struct mm_struct *mm = tlb->mm; > + struct vm_area_struct *vma = walk->vma; > + spinlock_t *ptl; > + pte_t *pte, ptent; > + struct page *page; > + > + split_huge_page_pmd(vma, addr, pmd); > + if (pmd_trans_unstable(pmd)) > + return 0; > + > + pte = pte_offset_map_lock(mm, pmd, addr, &ptl); > + arch_enter_lazy_mmu_mode(); > + for (; addr != end; pte++, addr += PAGE_SIZE) { > + ptent = *pte; > + > + if (!pte_present(ptent)) > + continue; > + > + page = vm_normal_page(vma, addr, ptent); > + if (!page) > + continue; > + > + if (PageSwapCache(page)) { > + if (!trylock_page(page)) > + continue; > + > + if (!try_to_free_swap(page)) { > + unlock_page(page); > + continue; > + } > + > + ClearPageDirty(page); > + unlock_page(page); > + } > + > + /* > + * Some of architecture(ex, PPC) don't update TLB > + * with set_pte_at and tlb_remove_tlb_entry so for > + * the portability, remap the pte with old|clean > + * after pte clearing. > + */ > + ptent = ptep_get_and_clear_full(mm, addr, pte, > + tlb->fullmm); > + ptent = pte_mkold(ptent); > + ptent = pte_mkclean(ptent); > + set_pte_at(mm, addr, pte, ptent); > + tlb_remove_tlb_entry(tlb, pte, addr); The orginal ptent might not be dirty. In that case, the tlb_remove_tlb_entry is unnecessary, so please add a check. In practice, I saw more TLB flush with FREE compared to DONTNEED because of this issue. Thanks, Shaohua -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>