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[PATCHv3 12/29] thp: support file pages in zap_huge_pmd()

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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.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 mm/huge_memory.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 79598ee8a3ff..15704484abf4 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1654,10 +1654,16 @@ 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));
-		atomic_long_dec(&tlb->mm->nr_ptes);
+		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(tlb, page);
 	}
-- 
2.7.0

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[PATCHv3 00/29] huge tmpfs implementation using compound pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-03-03 18:10 +0100
  [PATCHv3 25/29] truncate: handle file thp "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-03-03 18:10 +0100
  [PATCHv3 05/29] mm: do not pass mm_struct into handle_mm_fault "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-03-03 18:10 +0100
  [PATCHv3 12/29] thp: support file pages in zap_huge_pmd() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-03-03 18:10 +0100
  [PATCHv3 18/29] thp: run vma_adjust_trans_huge() outside i_mmap_rwsem "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-03-03 18:10 +0100
  [PATCHv3 29/29] shmem, thp: respect MADV_{NO,}HUGEPAGE for file mappings "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-03-03 18:10 +0100
  [PATCHv3 03/29] mm: make remove_migration_ptes() beyond mm/migration.c "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-03-03 18:10 +0100
  [PATCHv3 14/29] thp: handle file COW faults "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-03-03 18:10 +0100
  [PATCHv3 02/29] rmap: extend try_to_unmap() to be usable by split_huge_page() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-03-03 18:10 +0100
  [PATCHv3 01/29] rmap: introduce rmap_walk_locked() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-03-03 18:10 +0100
  [PATCHv3 07/29] mm: postpone page table allocation until we have page to map "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-03-03 18:10 +0100
  [PATCHv3 13/29] thp: handle file pages in split_huge_pmd() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-03-03 18:10 +0100
  [PATCHv3 15/29] thp: handle file pages in mremap() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-03-03 18:10 +0100
  [PATCHv3 20/29] thp, mlock: do not mlock PTE-mapped file huge pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-03-03 18:10 +0100
  [PATCHv3 08/29] rmap: support file thp "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-03-03 18:10 +0100
  [PATCHv3 16/29] thp: skip file huge pmd on copy_huge_pmd() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-03-03 18:10 +0100
  [PATCHv3 22/29] page-flags: relax policy for PG_mappedtodisk and PG_reclaim "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-03-03 18:10 +0100
  Re: [PATCHv3 00/29] huge tmpfs implementation using compound pages Sasha Levin <sasha.levin@oracle.com> - 2016-03-04 05:30 +0100

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