diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index d859d8bd1f96..e7cc0d860499 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -792,6 +792,18 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 		if (cur->vm_ops)
 			goto out_unlock;
 
+		/*
+		 * UFFDIO_COPY will fill file holes even without
+		 * PROT_WRITE. This check enforces that if this is a
+		 * MAP_SHARED, the process has write permission to the backing
+		 * file. If VM_MAYWRITE is set it also enforces that on a
+		 * MAP_SHARED vma: there is no F_WRITE_SEAL and no further
+		 * F_WRITE_SEAL can be taken until the vma is destroyed.
+		 */
+		ret = -EPERM;
+		if (unlikely(!(cur->vm_flags & VM_MAYWRITE)))
+			goto out_unlock;
+
 		/*
 		 * Check that this vma isn't already owned by a
 		 * different userfaultfd. We can't allow more than one
@@ -817,6 +829,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 		BUG_ON(vma->vm_ops);
 		BUG_ON(vma->vm_userfaultfd_ctx.ctx &&
 		       vma->vm_userfaultfd_ctx.ctx != ctx);
+		WARN_ON(!(vma->vm_flags & VM_MAYWRITE));
 
 		/*
 		 * Nothing to do: this vma is already registered into this
@@ -953,6 +966,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 		cond_resched();
 
 		BUG_ON(vma->vm_ops);
+		WARN_ON(!(vma->vm_flags & VM_MAYWRITE));
 
 		/*
 		 * Nothing to do: this vma is already registered into this
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 77fee9325a57..497248b93a4c 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -182,13 +182,9 @@ retry:
 		goto out_unlock;
 
 	/*
-	 * Be strict and only allow __mcopy_atomic on userfaultfd
-	 * registered ranges to prevent userland errors going
-	 * unnoticed. As far as the VM consistency is concerned, it
-	 * would be perfectly safe to remove this check, but there's
-	 * no useful usage for __mcopy_atomic ouside of userfaultfd
-	 * registered ranges. This is after all why these are ioctls
-	 * belonging to the userfaultfd and not syscalls.
+	 * Check the vma is registered in uffd, this is required to
+	 * enforce the VM_MAYWRITE check done at uffd registration
+	 * time.
 	 */
 	if (!dst_vma->vm_userfaultfd_ctx.ctx)
 		goto out_unlock;