thp: support file pages in zap_huge_pmd() (b5072380) · Commits · 戴 / test

split_huge_pmd() for file mappings (and DAX too) is implemented by just clearing pmd entry as we can re-fill this area from page cache on pte level later. This means we don't need deposit page tables when file THP is mapped. Therefore we shouldn't try to withdraw a page table on zap_huge_pmd() file THP PMD. Link: http://lkml.kernel.org/r/1466021202-61880-14-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by:

Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

mm/huge_memory.c

+9 −3

Original line number	Diff line number	Diff line
		@@ -1689,10 +1689,16 @@ int zap_huge_pmd(struct mmu_gather tlb, struct vm_area_struct vma,
		struct page *page = pmd_page(orig_pmd);
		page_remove_rmap(page, true);
		VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
		add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
		VM_BUG_ON_PAGE(!PageHead(page), page);
		pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd));
		if (PageAnon(page)) {
		pgtable_t pgtable;
		pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd);
		pte_free(tlb->mm, pgtable);
		atomic_long_dec(&tlb->mm->nr_ptes);
		add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
		} else {
		add_mm_counter(tlb->mm, MM_FILEPAGES, -HPAGE_PMD_NR);
		}
		spin_unlock(ptl);
		tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
		}

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