[PATCH v3 02/10] thp: zap_huge_pmd(): zap huge zero pmd

From: Kirill A. Shutemov
Date: Tue Oct 02 2012 - 11:18:50 EST


From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxx>
Reviewed-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
---
mm/huge_memory.c | 27 +++++++++++++++++----------
1 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 50c44e9..140d858 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1072,16 +1072,23 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
struct page *page;
pgtable_t pgtable;
pgtable = get_pmd_huge_pte(tlb->mm);
- page = pmd_page(*pmd);
- pmd_clear(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(*pmd)) {
+ pmd_clear(pmd);
+ tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
+ tlb->mm->nr_ptes--;
+ spin_unlock(&tlb->mm->page_table_lock);
+ } else {
+ page = pmd_page(*pmd);
+ pmd_clear(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);
+ }
pte_free(tlb->mm, pgtable);
ret = 1;
}
--
1.7.7.6

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/