Messages in this thread | | | From | HORIGUCHI NAOYA(堀口 直也) <> | Subject | Re: [PATCH v1 5/5] mm, hwpoison: enable memory error handling on 1GB hugepage | Date | Wed, 8 Jun 2022 06:16:36 +0000 |
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On Tue, Jun 07, 2022 at 10:11:24PM +0800, Miaohe Lin wrote: > On 2022/6/2 13:06, Naoya Horiguchi wrote: > > From: Naoya Horiguchi <naoya.horiguchi@nec.com> > > > > Now error handling code is prepared, so remove the blocking code and > > enable memory error handling on 1GB hugepage. > > > > I'm nervous about this change. It seems there are many code paths not awared of pud swap entry. > I browsed some of them: > apply_to_pud_range called from apply_to_page_range: > > apply_to_pud_range: > next = pud_addr_end(addr, end); > if (pud_none(*pud) && !create) > continue; > if (WARN_ON_ONCE(pud_leaf(*pud))) > return -EINVAL; > if (!pud_none(*pud) && WARN_ON_ONCE(pud_bad(*pud))) { > if (!create) > continue; > pud_clear_bad(pud); > } > err = apply_to_pmd_range(mm, pud, addr, next, > fn, data, create, mask); > > For !pud_present case, it will mostly reach apply_to_pmd_range and call pmd_offset on it. And invalid > pointer will be de-referenced.
apply_to_pmd_range() has BUG_ON(pud_huge(*pud)) and apply_to_pte_range() has BUG_ON(pmd_huge(*pmd)), so this page table walking code seems to not expect to handle pmd/pud level mapping.
> > Another example might be copy_pud_range and so on. So I think it might not be prepared to enable the > 1GB hugepage or all of these places should be fixed?
I think that most of page table walker for user address space should first check is_vm_hugetlb_page() and call hugetlb specific walking code for vma with VM_HUGETLB. copy_page_range() is a good example. It calls copy_hugetlb_page_range() for vma with VM_HUGETLB and the function should support hwpoison entry. But I feel that I need testing for confirmation.
And I'm not sure that all other are prepared for non-present pud-mapping, so I'll need somehow code inspection and testing for each.
Thanks, Naoya Horiguchi | |