@@ -1838,10 +1838,10 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
if (is_swap_pmd(*pmd)) {
swp_entry_t entry = pmd_to_swp_entry(*pmd);
struct page *page = pfn_swap_entry_to_page(entry);
+ pmd_t newpmd;
VM_BUG_ON(!is_pmd_migration_entry(*pmd));
if (is_writable_migration_entry(entry)) {
- pmd_t newpmd;
/*
* A protection check is difficult so
* just be safe and disable write
@@ -1855,8 +1855,16 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
newpmd = pmd_swp_mksoft_dirty(newpmd);
if (pmd_swp_uffd_wp(*pmd))
newpmd = pmd_swp_mkuffd_wp(newpmd);
- set_pmd_at(mm, addr, pmd, newpmd);
+ } else {
+ newpmd = *pmd;
}
+
+ if (uffd_wp)
+ newpmd = pmd_swp_mkuffd_wp(newpmd);
+ else if (uffd_wp_resolve)
+ newpmd = pmd_swp_clear_uffd_wp(newpmd);
+ if (!pmd_same(*pmd, newpmd))
+ set_pmd_at(mm, addr, pmd, newpmd);
goto unlock;
}
#endif
@@ -3251,6 +3259,8 @@ int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
pmdswp = swp_entry_to_pmd(entry);
if (pmd_soft_dirty(pmdval))
pmdswp = pmd_swp_mksoft_dirty(pmdswp);
+ if (pmd_uffd_wp(pmdval))
+ pmdswp = pmd_swp_mkuffd_wp(pmdswp);
set_pmd_at(mm, address, pvmw->pmd, pmdswp);
page_remove_rmap(page, vma, true);
put_page(page);
Looks like what we fixed for hugetlb in commit 44f86392bdd1 ("mm/hugetlb: fix uffd-wp handling for migration entries in hugetlb_change_protection()") similarly applies to THP. Setting/clearing uffd-wp on THP migration entries is not implemented properly. Further, while removing migration PMDs considers the uffd-wp bit, inserting migration PMDs does not consider the uffd-wp bit. We have to set/clear independently of the migration entry type in change_huge_pmd() and properly copy the uffd-wp bit in set_pmd_migration_entry(). Verified using a simple reproducer that triggers migration of a THP, that the set_pmd_migration_entry() no longer loses the uffd-wp bit. Fixes: f45ec5ff16a7 ("userfaultfd: wp: support swap and page migration") Reviewed-by: Peter Xu <peterx@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: David Hildenbrand <david@redhat.com> --- mm/huge_memory.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)