| Message ID | 20230413231120.544685-3-peterx@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/hugetlb: More fixes around uffd-wp vs fork() / RO pins | expand |
On 14.04.23 01:11, 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 <stable@vger.kernel.org> > Fixes: 166f3ecc0daf ("mm/hugetlb: hook page faults for uffd write protection") > Reported-by: Mike Kravetz <mike.kravetz@oracle.com> > Signed-off-by: Peter Xu <peterx@redhat.com> > --- > 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); LGTM, thanks Reviewed-by: David Hildenbrand <david@redhat.com>
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 <stable@vger.kernel.org> > Fixes: 166f3ecc0daf ("mm/hugetlb: hook page faults for uffd write protection") > Reported-by: Mike Kravetz <mike.kravetz@oracle.com> > Signed-off-by: Peter Xu <peterx@redhat.com> > --- > 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@oracle.com>
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);
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 <stable@vger.kernel.org> Fixes: 166f3ecc0daf ("mm/hugetlb: hook page faults for uffd write protection") Reported-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Peter Xu <peterx@redhat.com> --- mm/hugetlb.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)