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Commit b5072380 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
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thp: support file pages in zap_huge_pmd() 

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: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 95ecedcd

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);

	}