Messages in this thread | | | Date | Thu, 15 Nov 2012 13:52:44 -0800 (PST) | From | David Rientjes <> | Subject | Re: [PATCH v5 08/11] thp: setup huge zero page on non-write page fault |
| |
On Thu, 15 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". >
If the pte_alloc_one(), which wraps __pte_alloc(), you're adding fails, it's pointless to "goto out" to try __pte_alloc() which we know won't succeed.
> Should it be fixed too? >
It's done for maintainablility because although __do_huge_pmd_anonymous_page() will only return VM_FAULT_OOM today when pte_alloc_one() fails, if it were to ever fail in a different way then the caller is already has a graceful failure.
| |