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 vEzEL63/ 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 04/13/23 19:11, Peter Xu wrote: > When we try to unshare a pinned page for a private hugetlb, uffd-wp bit can > get lost during unsharing. Fix it by carrying it over. > > This should be very rare, only if an unsharing happened on a private > hugetlb page with uffd-wp protected (e.g. in a child which shares the same > page with parent with UFFD_FEATURE_EVENT_FORK enabled). > > Cc: linux-stable > Fixes: 166f3ecc0daf ("mm/hugetlb: hook page faults for uffd write protection") > Reported-by: Mike Kravetz > Signed-off-by: Peter Xu > --- > mm/hugetlb.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 7320e64aacc6..083aae35bff8 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -5637,13 +5637,16 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma, > spin_lock(ptl); > ptep = hugetlb_walk(vma, haddr, huge_page_size(h)); > if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) { > + pte_t newpte = make_huge_pte(vma, &new_folio->page, !unshare); > + > /* Break COW or unshare */ > huge_ptep_clear_flush(vma, haddr, ptep); > mmu_notifier_invalidate_range(mm, range.start, range.end); > page_remove_rmap(old_page, vma, true); > hugepage_add_new_anon_rmap(new_folio, vma, haddr); > - set_huge_pte_at(mm, haddr, ptep, > - make_huge_pte(vma, &new_folio->page, !unshare)); > + if (huge_pte_uffd_wp(pte)) > + newpte = huge_pte_mkuffd_wp(newpte); > + set_huge_pte_at(mm, haddr, ptep, newpte); > folio_set_hugetlb_migratable(new_folio); > /* Make the old page be freed below */ > new_folio = page_folio(old_page); > -- > 2.39.1 > Thanks! Looks good, Reviewed-by: Mike Kravetz -- Mike Kravetz