1 files changed, 37 insertions, 0 deletions
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 27978f249016..68f978beefac 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -596,6 +596,43 @@ void dup_userfaultfd_complete(struct list_head *fcs)
 	}
 }
 
+void mremap_userfaultfd_prep(struct vm_area_struct *vma,
+			     struct vm_userfaultfd_ctx *vm_ctx)
+{
+	struct userfaultfd_ctx *ctx;
+
+	ctx = vma->vm_userfaultfd_ctx.ctx;
+	if (ctx && (ctx->features & UFFD_FEATURE_EVENT_REMAP)) {
+		vm_ctx->ctx = ctx;
+		userfaultfd_ctx_get(ctx);
+	}
+}
+
+void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx vm_ctx,
+				 unsigned long from, unsigned long to,
+				 unsigned long len)
+{
+	struct userfaultfd_ctx *ctx = vm_ctx.ctx;
+	struct userfaultfd_wait_queue ewq;
+
+	if (!ctx)
+		return;
+
+	if (to & ~PAGE_MASK) {
+		userfaultfd_ctx_put(ctx);
+		return;
+	}
+
+	msg_init(&ewq.msg);
+
+	ewq.msg.event = UFFD_EVENT_REMAP;
+	ewq.msg.arg.remap.from = from;
+	ewq.msg.arg.remap.to = to;
+	ewq.msg.arg.remap.len = len;
+
+	userfaultfd_event_wait_completion(ctx, &ewq);
+}
+
 static int userfaultfd_release(struct inode *inode, struct file *file)
 {
 	struct userfaultfd_ctx *ctx = file->private_data;