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Diffstat (limited to 'mm/userfaultfd.c')
-rw-r--r--mm/userfaultfd.c29
1 files changed, 20 insertions, 9 deletions
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 20e3b0d9cf7e..7cf7d4384259 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -357,6 +357,7 @@ static __always_inline ssize_t mfill_atomic_hugetlb(
unsigned long dst_start,
unsigned long src_start,
unsigned long len,
+ atomic_t *mmap_changing,
uffd_flags_t flags)
{
struct mm_struct *dst_mm = dst_vma->vm_mm;
@@ -472,6 +473,15 @@ retry:
goto out;
}
mmap_read_lock(dst_mm);
+ /*
+ * If memory mappings are changing because of non-cooperative
+ * operation (e.g. mremap) running in parallel, bail out and
+ * request the user to retry later
+ */
+ if (mmap_changing && atomic_read(mmap_changing)) {
+ err = -EAGAIN;
+ break;
+ }
dst_vma = NULL;
goto retry;
@@ -506,6 +516,7 @@ extern ssize_t mfill_atomic_hugetlb(struct vm_area_struct *dst_vma,
unsigned long dst_start,
unsigned long src_start,
unsigned long len,
+ atomic_t *mmap_changing,
uffd_flags_t flags);
#endif /* CONFIG_HUGETLB_PAGE */
@@ -622,8 +633,8 @@ retry:
* If this is a HUGETLB vma, pass off to appropriate routine
*/
if (is_vm_hugetlb_page(dst_vma))
- return mfill_atomic_hugetlb(dst_vma, dst_start,
- src_start, len, flags);
+ return mfill_atomic_hugetlb(dst_vma, dst_start, src_start,
+ len, mmap_changing, flags);
if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma))
goto out_unlock;
@@ -891,8 +902,8 @@ static int move_present_pte(struct mm_struct *mm,
double_pt_lock(dst_ptl, src_ptl);
- if (!pte_same(*src_pte, orig_src_pte) ||
- !pte_same(*dst_pte, orig_dst_pte)) {
+ if (!pte_same(ptep_get(src_pte), orig_src_pte) ||
+ !pte_same(ptep_get(dst_pte), orig_dst_pte)) {
err = -EAGAIN;
goto out;
}
@@ -935,8 +946,8 @@ static int move_swap_pte(struct mm_struct *mm,
double_pt_lock(dst_ptl, src_ptl);
- if (!pte_same(*src_pte, orig_src_pte) ||
- !pte_same(*dst_pte, orig_dst_pte)) {
+ if (!pte_same(ptep_get(src_pte), orig_src_pte) ||
+ !pte_same(ptep_get(dst_pte), orig_dst_pte)) {
double_pt_unlock(dst_ptl, src_ptl);
return -EAGAIN;
}
@@ -1005,7 +1016,7 @@ retry:
}
spin_lock(dst_ptl);
- orig_dst_pte = *dst_pte;
+ orig_dst_pte = ptep_get(dst_pte);
spin_unlock(dst_ptl);
if (!pte_none(orig_dst_pte)) {
err = -EEXIST;
@@ -1013,7 +1024,7 @@ retry:
}
spin_lock(src_ptl);
- orig_src_pte = *src_pte;
+ orig_src_pte = ptep_get(src_pte);
spin_unlock(src_ptl);
if (pte_none(orig_src_pte)) {
if (!(mode & UFFDIO_MOVE_MODE_ALLOW_SRC_HOLES))
@@ -1043,7 +1054,7 @@ retry:
* page isn't freed under us
*/
spin_lock(src_ptl);
- if (!pte_same(orig_src_pte, *src_pte)) {
+ if (!pte_same(orig_src_pte, ptep_get(src_pte))) {
spin_unlock(src_ptl);
err = -EAGAIN;
goto out;