The behavior here is the same as it is for anon/shmem. This is done
separately because hugetlb pte marker handling is a bit different.
Signed-off-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
---
mm/hugetlb.c | 33 +++++++++++++++++++++++++++++++--
mm/userfaultfd.c | 6 +-----
2 files changed, 32 insertions(+), 7 deletions(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 38711d49e4db..05abe88986b6 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6090,14 +6090,24 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
}
entry = huge_ptep_get(ptep);
- /* PTE markers should be handled the same way as none pte */
- if (huge_pte_none_mostly(entry))
+ if (huge_pte_none_mostly(entry)) {
+ if (is_pte_marker(entry)) {
+ unsigned long marker = pte_marker_get(pte_to_swp_entry(entry));
+
+ if (marker & PTE_MARKER_UFFD_POISON) {
+ ret = VM_FAULT_HWPOISON_LARGE;
+ goto out_mutex;
+ }
+ }
/*
+ * Other PTE markers should be handled the same way as none PTE.
+ *
* hugetlb_no_page will drop vma lock and hugetlb fault
* mutex internally, which make us return immediately.
*/
return hugetlb_no_page(mm, vma, mapping, idx, address, ptep,
entry, flags);
+ }
ret = 0;
@@ -6253,6 +6263,25 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_pte,
int writable;
bool folio_in_pagecache = false;
+ if (uffd_flags_mode_is(flags, MFILL_ATOMIC_POISON)) {
+ ptl = huge_pte_lock(h, dst_mm, dst_pte);
+
+ /* Don't overwrite any existing PTEs (even markers) */
+ if (!huge_pte_none(huge_ptep_get(dst_pte))) {
+ spin_unlock(ptl);
+ return -EEXIST;
+ }
+
+ _dst_pte = make_pte_marker(PTE_MARKER_UFFD_POISON);
+ set_huge_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
+
+ /* No need to invalidate - it was non-present before */
+ update_mmu_cache(dst_vma, dst_addr, dst_pte);
+
+ spin_unlock(ptl);
+ return 0;
+ }
+
if (is_continue) {
ret = -EFAULT;
folio = filemap_lock_folio(mapping, idx);
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 87b62ca1e09e..4436cae1c7a8 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -381,12 +381,8 @@ static __always_inline ssize_t mfill_atomic_hugetlb(
* supported by hugetlb. A PMD_SIZE huge pages may exist as used
* by THP. Since we can not reliably insert a zero page, this
* feature is not supported.
- *
- * PTE marker handling for hugetlb is a bit special, so for now
- * UFFDIO_POISON is not supported.
*/
- if (uffd_flags_mode_is(flags, MFILL_ATOMIC_ZEROPAGE) ||
- uffd_flags_mode_is(flags, MFILL_ATOMIC_POISON)) {
+ if (uffd_flags_mode_is(flags, MFILL_ATOMIC_ZEROPAGE)) {
mmap_read_unlock(dst_mm);
return -EINVAL;
}
--
2.41.0.255.g8b1d071c50-goog
