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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.

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>
This commit is contained in:
Kirill A. Shutemov 2016-07-26 15:25:34 -07:00 committed by Linus Torvalds
parent 95ecedcd6a
commit b5072380eb
1 changed files with 9 additions and 3 deletions
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12
mm/huge_memory.c
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@ -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));
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_size(tlb, page, HPAGE_PMD_SIZE);
}