Messages in this thread | | | Date | Thu, 12 Nov 2015 13:26:20 +0200 | From | "Kirill A. Shutemov" <> | Subject | Re: [PATCH v3 01/17] mm: support madvise(MADV_FREE) |
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On Thu, Nov 12, 2015 at 01:32:57PM +0900, Minchan Kim wrote: > @@ -256,6 +260,125 @@ static long madvise_willneed(struct vm_area_struct *vma, > return 0; > } > > +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)) {
Could you put VM_BUG_ON_PAGE(PageTransCompound(page), page) here? Just in case.
> + if (!trylock_page(page)) > + continue; > + > + if (!try_to_free_swap(page)) { > + unlock_page(page); > + continue; > + } > + > + ClearPageDirty(page); > + unlock_page(page);
Hm. Do we handle pages shared over fork() here? Souldn't we ignore pages with mapcount > 0?
> + } > + > + if (pte_young(ptent) || pte_dirty(ptent)) { > + /* > + * 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); > + } > + } > + > + arch_leave_lazy_mmu_mode(); > + pte_unmap_unlock(pte - 1, ptl); > + cond_resched(); > + return 0; > +} >
-- Kirill A. Shutemov
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