Re: [PATCH v5 08/11] thp: setup huge zero page on non-write page fault

Kirill A. Shutemov
2012-11-15T09:31:05Z

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On Wed, Nov 14, 2012 at 03:33:16PM -0800, David Rientjes wrote:
> On Wed, 7 Nov 2012, Kirill A. Shutemov wrote:
>
> > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > index f36bc7d..41f05f1 100644
> > --- a/mm/huge_memory.c
> > +++ b/mm/huge_memory.c
> > @@ -726,6 +726,16 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
> > return VM_FAULT_OOM;
> > if (unlikely(khugepaged_enter(vma)))
> > return VM_FAULT_OOM;
> > + if (!(flags & FAULT_FLAG_WRITE)) {
> > + pgtable_t pgtable;
> > + pgtable = pte_alloc_one(mm, haddr);
> > + if (unlikely(!pgtable))
> > + goto out;
>
> No use in retrying, just return VM_FAULT_OOM.

Hm. It's consistent with non-hzp path: if pte_alloc_one() in
__do_huge_pmd_anonymous_page() fails __do_huge_pmd_anonymous_page()
returns VM_FAULT_OOM which leads to "goto out".

Should it be fixed too?

>
> > + spin_lock(&mm->page_table_lock);
> > + set_huge_zero_page(pgtable, mm, vma, haddr, pmd);
> > + spin_unlock(&mm->page_table_lock);
> > + return 0;
> > + }
> > page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
> > vma, haddr, numa_node_id(), 0);
> > if (unlikely(!page)) {

--
Kirill A. Shutemov

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