Messages in this thread | | | Subject | Re: [PATCH v2 2/9] mm/hugetlb: separate path for hwpoison entry in copy_hugetlb_page_range() | From | Miaohe Lin <> | Date | Fri, 24 Jun 2022 17:23:41 +0800 |
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On 2022/6/24 7:51, Naoya Horiguchi wrote: > From: Naoya Horiguchi <naoya.horiguchi@nec.com> > > Originally copy_hugetlb_page_range() handles migration entries and hwpoisone
s/hwpoisone/hwpoisoned/
> entries in similar manner. But recently the related code path has more code > for migration entries, and when is_writable_migration_entry() was converted > to !is_readable_migration_entry(), hwpoison entries on source processes got > to be unexpectedly updated (which is legitimate for migration entries, but > not for hwpoison entries). This results in unexpected serious issues like > kernel panic when foking processes with hwpoison entries in pmd.
s/foking/forking/
> > Separate the if branch into one for hwpoison entries and one for migration > entries. > > Fixes: 6c287605fd56 ("mm: remember exclusively mapped anonymous pages with PG_anon_exclusive") > Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> > Cc: <stable@vger.kernel.org> # 5.18
This makes sense to me. Thanks for fixing this.
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
> --- > mm/hugetlb.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index c538278170a2..f59f43c06601 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -4784,8 +4784,13 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, > * sharing with another vma. > */ > ; > - } else if (unlikely(is_hugetlb_entry_migration(entry) || > - is_hugetlb_entry_hwpoisoned(entry))) { > + } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry))) { > + bool uffd_wp = huge_pte_uffd_wp(entry); > + > + if (!userfaultfd_wp(dst_vma) && uffd_wp) > + entry = huge_pte_clear_uffd_wp(entry); > + set_huge_swap_pte_at(dst, addr, dst_pte, entry, sz); > + } else if (unlikely(is_hugetlb_entry_migration(entry))) { > swp_entry_t swp_entry = pte_to_swp_entry(entry); > bool uffd_wp = huge_pte_uffd_wp(entry); > >
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