| Date | Tue, 19 May 2015 15:55:12 +0200 | From | Vlastimil Babka <> | Subject | Re: [PATCHv5 23/28] thp: add option to setup migration entiries during PMD split |
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On 04/23/2015 11:03 PM, Kirill A. Shutemov wrote: > We are going to use migration PTE entires to stabilize page counts. > If the page is mapped with PMDs we need to split the PMD and setup > migration enties. It's reasonable to combine these operations to avoid > double-scanning over the page table. > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > Tested-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
> --- > mm/huge_memory.c | 23 +++++++++++++++-------- > 1 file changed, 15 insertions(+), 8 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 5885ef8f0fad..2f9e2e882bab 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -23,6 +23,7 @@ > #include <linux/pagemap.h> > #include <linux/migrate.h> > #include <linux/hashtable.h> > +#include <linux/swapops.h> > > #include <asm/tlb.h> > #include <asm/pgalloc.h> > @@ -2551,7 +2552,7 @@ 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; > @@ -2593,12 +2594,18 @@ 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); > @@ -2625,7 +2632,7 @@ 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); > } >
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