From ba98828088ad3ffa7ee4d5b017c291934fcbaeb9 Mon Sep 17 00:00:00 2001 From: Kirill A. Shutemov Date: Fri, 15 Jan 2016 16:53:56 -0800 Subject: thp: add option to setup migration entries during PMD split We are going to use migration PTE entries to stabilize page counts. If the page is mapped with PMDs we need to split the PMD and setup migration entries. It's reasonable to combine these operations to avoid double-scanning over the page table. Signed-off-by: Kirill A. Shutemov Tested-by: Sasha Levin Tested-by: Aneesh Kumar K.V Acked-by: Vlastimil Babka Acked-by: Jerome Marchand Cc: Andrea Arcangeli Cc: Hugh Dickins Cc: Dave Hansen Cc: Mel Gorman Cc: Rik van Riel Cc: Naoya Horiguchi Cc: Steve Capper Cc: Johannes Weiner Cc: Michal Hocko Cc: Christoph Lameter Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/huge_memory.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) (limited to 'mm/huge_memory.c') diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 22ab365cce52..913559388fda 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2695,7 +2695,7 @@ static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, } static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, - unsigned long haddr) + unsigned long haddr, bool freeze) { struct mm_struct *mm = vma->vm_mm; struct page *page; @@ -2739,12 +2739,18 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, * transferred to avoid any possibility of altering * permissions across VMAs. */ - entry = mk_pte(page + i, vma->vm_page_prot); - entry = maybe_mkwrite(pte_mkdirty(entry), vma); - if (!write) - entry = pte_wrprotect(entry); - if (!young) - entry = pte_mkold(entry); + if (freeze) { + swp_entry_t swp_entry; + swp_entry = make_migration_entry(page + i, write); + entry = swp_entry_to_pte(swp_entry); + } else { + entry = mk_pte(page + i, vma->vm_page_prot); + entry = maybe_mkwrite(pte_mkdirty(entry), vma); + if (!write) + entry = pte_wrprotect(entry); + if (!young) + entry = pte_mkold(entry); + } pte = pte_offset_map(&_pmd, haddr); BUG_ON(!pte_none(*pte)); set_pte_at(mm, haddr, pte, entry); @@ -2785,7 +2791,7 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE); ptl = pmd_lock(mm, pmd); if (likely(pmd_trans_huge(*pmd))) - __split_huge_pmd_locked(vma, pmd, haddr); + __split_huge_pmd_locked(vma, pmd, haddr, false); spin_unlock(ptl); mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE); } -- cgit v1.2.3-55-g7522