[PATCH v5 02/11] thp: zap_huge_pmd(): zap huge zero pmd

Kirill A. Shutemov
2012-11-07T15:00:15Z

From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>

We don't have a real page to zap in huge zero page case. Let's just
clear pmd and remove it from tlb.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
mm/huge_memory.c | 21 +++++++++++++--------
1 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index e5ce979..ff834ea 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1058,15 +1058,20 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
pmd_t orig_pmd;
pgtable = pgtable_trans_huge_withdraw(tlb->mm);
orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd);
- page = pmd_page(orig_pmd);
tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
- page_remove_rmap(page);
- VM_BUG_ON(page_mapcount(page) < 0);
- add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
- VM_BUG_ON(!PageHead(page));
- tlb->mm->nr_ptes--;
- spin_unlock(&tlb->mm->page_table_lock);
- tlb_remove_page(tlb, page);
+ if (is_huge_zero_pmd(orig_pmd)) {
+ tlb->mm->nr_ptes--;
+ spin_unlock(&tlb->mm->page_table_lock);
+ } else {
+ page = pmd_page(orig_pmd);
+ page_remove_rmap(page);
+ VM_BUG_ON(page_mapcount(page) < 0);
+ add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
+ VM_BUG_ON(!PageHead(page));
+ tlb->mm->nr_ptes--;
+ spin_unlock(&tlb->mm->page_table_lock);
+ tlb_remove_page(tlb, page);
+ }
pte_free(tlb->mm, pgtable);
ret = 1;
}
--
1.7.7.6