Re: [PATCH v3 01/17] mm: support madvise(MADV_FREE)
From: Kirill A. Shutemov <hidden>
Date: 2015-11-12 11:26:26
Also in:
linux-mm, lkml
On Thu, Nov 12, 2015 at 01:32:57PM +0900, Minchan Kim wrote:
quoted hunk ↗ jump to hunk
@@ -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