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-rw-r--r--mm/userfaultfd.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 650ab6cfd..992a0a168 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -327,6 +327,7 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
unsigned long dst_start,
unsigned long src_start,
unsigned long len,
+ atomic_t *mmap_changing,
enum mcopy_atomic_mode mode,
bool wp_copy)
{
@@ -445,6 +446,15 @@ 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;
@@ -480,6 +490,7 @@ extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
unsigned long dst_start,
unsigned long src_start,
unsigned long len,
+ atomic_t *mmap_changing,
enum mcopy_atomic_mode mode,
bool wp_copy);
#endif /* CONFIG_HUGETLB_PAGE */
@@ -601,8 +612,8 @@ retry:
*/
if (is_vm_hugetlb_page(dst_vma))
return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start,
- src_start, len, mcopy_mode,
- wp_copy);
+ src_start, len, mmap_changing,
+ mcopy_mode, wp_copy);
if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma))
goto out_unlock;