--- a/mm/mremap.c~mm-mremap-reset-unfaulted-vma-page-offset-for-mremap_dontunmap
+++ a/mm/mremap.c
@@ -1331,18 +1331,30 @@ static void dontunmap_complete(struct vm
 {
 	unsigned long start = vrm->addr;
 	unsigned long end = vrm->addr + vrm->old_len;
-	unsigned long old_start = vrm->vma->vm_start;
-	unsigned long old_end = vrm->vma->vm_end;
+	struct vm_area_struct *vma = vrm->vma;
+	unsigned long old_start = vma->vm_start;
+	unsigned long old_end = vma->vm_end;
 
 	/* We always clear VMA_LOCKED[ONFAULT]_BIT on the old VMA. */
-	vma_clear_flags_mask(vrm->vma, VMA_LOCKED_MASK);
+	vma_clear_flags_mask(vma, VMA_LOCKED_MASK);
 
 	/*
 	 * anon_vma links of the old vma is no longer needed after its page
 	 * table has been moved.
 	 */
-	if (new_vma != vrm->vma && start == old_start && end == old_end)
-		unlink_anon_vmas(vrm->vma);
+	if (new_vma != vma && start == old_start && end == old_end) {
+		const pgoff_t pgoff_unfaulted = vma->vm_start >> PAGE_SHIFT;
+
+		unlink_anon_vmas(vma);
+		/*
+		 * The VMA is now unfaulted and it is an invariant that
+		 * unfaulted anonymous VMAs have page offset equal to
+		 * vma->vm_start >> PAGE_SHIFT.
+		 */
+		vma_set_anon_pgoff(vma, pgoff_unfaulted);
+		if (vma_is_anonymous(vma) && !vma->vm_file)
+			vma_set_pgoff(vma, pgoff_unfaulted);
+	}
 
 	/* Because we won't unmap we don't need to touch locked_vm. */
 }