Re: [PATCH v3 07/10] thp: implement splitting pmd for huge zero page

From: Kirill A. Shutemov
Date: Fri Oct 12 2012 - 00:12:07 EST


On Fri, Oct 12, 2012 at 11:23:37AM +0800, Ni zhan Chen wrote:
> On 10/02/2012 11:19 PM, Kirill A. Shutemov wrote:
> >From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
> >
> >We can't split huge zero page itself, but we can split the pmd which
> >points to it.
> >
> >On splitting the pmd we create a table with all ptes set to normal zero
> >page.
> >
> >Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> >Reviewed-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> >---
> > mm/huge_memory.c | 32 ++++++++++++++++++++++++++++++++
> > 1 files changed, 32 insertions(+), 0 deletions(-)
> >
> >diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> >index 95032d3..3f1c59c 100644
> >--- a/mm/huge_memory.c
> >+++ b/mm/huge_memory.c
> >@@ -1600,6 +1600,7 @@ int split_huge_page(struct page *page)
> > struct anon_vma *anon_vma;
> > int ret = 1;
> >+ BUG_ON(is_huge_zero_pfn(page_to_pfn(page)));
> > BUG_ON(!PageAnon(page));
> > anon_vma = page_lock_anon_vma(page);
> > if (!anon_vma)
> >@@ -2503,6 +2504,32 @@ static int khugepaged(void *none)
> > return 0;
> > }
> >+static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
> >+ unsigned long haddr, pmd_t *pmd)
> >+{
> >+ pgtable_t pgtable;
> >+ pmd_t _pmd;
> >+ int i;
> >+
> >+ pmdp_clear_flush_notify(vma, haddr, pmd);
>
> why I can't find function pmdp_clear_flush_notify in kernel source
> code? Do you mean pmdp_clear_flush_young_notify or something like
> that?

It was changed recently. See commit
2ec74c3 mm: move all mmu notifier invocations to be done outside the PT lock

--
Kirill A. Shutemov
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