diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 9395515..96ea377 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -65,6 +65,8 @@
 	enum userfaultfd_state state;
 	/* released */
 	bool released;
+	/* memory mappings are changing because of non-cooperative event */
+	bool mmap_changing;
 	/* mm with one ore more vmas attached to this userfaultfd_ctx */
 	struct mm_struct *mm;
 };
@@ -653,6 +655,7 @@
 	 * already released.
 	 */
 out:
+	WRITE_ONCE(ctx->mmap_changing, false);
 	userfaultfd_ctx_put(ctx);
 }
 
@@ -698,10 +701,12 @@
 		ctx->state = UFFD_STATE_RUNNING;
 		ctx->features = octx->features;
 		ctx->released = false;
+		ctx->mmap_changing = false;
 		ctx->mm = vma->vm_mm;
 		atomic_inc(&ctx->mm->mm_count);
 
 		userfaultfd_ctx_get(octx);
+		WRITE_ONCE(octx->mmap_changing, true);
 		fctx->orig = octx;
 		fctx->new = ctx;
 		list_add_tail(&fctx->list, fcs);
@@ -744,6 +749,7 @@
 	if (ctx && (ctx->features & UFFD_FEATURE_EVENT_REMAP)) {
 		vm_ctx->ctx = ctx;
 		userfaultfd_ctx_get(ctx);
+		WRITE_ONCE(ctx->mmap_changing, true);
 	} else {
 		/* Drop uffd context if remap feature not enabled */
 		vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
@@ -788,6 +794,7 @@
 		return true;
 
 	userfaultfd_ctx_get(ctx);
+	WRITE_ONCE(ctx->mmap_changing, true);
 	up_read(&mm->mmap_sem);
 
 	msg_init(&ewq.msg);
@@ -831,6 +838,7 @@
 			return -ENOMEM;
 
 		userfaultfd_ctx_get(ctx);
+		WRITE_ONCE(ctx->mmap_changing, true);
 		unmap_ctx->ctx = ctx;
 		unmap_ctx->start = start;
 		unmap_ctx->end = end;
@@ -1723,6 +1731,10 @@
 
 	user_uffdio_copy = (struct uffdio_copy __user *) arg;
 
+	ret = -EAGAIN;
+	if (READ_ONCE(ctx->mmap_changing))
+		goto out;
+
 	ret = -EFAULT;
 	if (copy_from_user(&uffdio_copy, user_uffdio_copy,
 			   /* don't copy "copy" last field */
@@ -1744,7 +1756,7 @@
 		goto out;
 	if (mmget_not_zero(ctx->mm)) {
 		ret = mcopy_atomic(ctx->mm, uffdio_copy.dst, uffdio_copy.src,
-				   uffdio_copy.len);
+				   uffdio_copy.len, &ctx->mmap_changing);
 		mmput(ctx->mm);
 	} else {
 		return -ESRCH;
@@ -1775,6 +1787,10 @@
 
 	user_uffdio_zeropage = (struct uffdio_zeropage __user *) arg;
 
+	ret = -EAGAIN;
+	if (READ_ONCE(ctx->mmap_changing))
+		goto out;
+
 	ret = -EFAULT;
 	if (copy_from_user(&uffdio_zeropage, user_uffdio_zeropage,
 			   /* don't copy "zeropage" last field */
@@ -1791,7 +1807,8 @@
 
 	if (mmget_not_zero(ctx->mm)) {
 		ret = mfill_zeropage(ctx->mm, uffdio_zeropage.range.start,
-				     uffdio_zeropage.range.len);
+				     uffdio_zeropage.range.len,
+				     &ctx->mmap_changing);
 		mmput(ctx->mm);
 	} else {
 		return -ESRCH;
@@ -2004,6 +2021,7 @@
 	ctx->features = 0;
 	ctx->state = UFFD_STATE_WAIT_API;
 	ctx->released = false;
+	ctx->mmap_changing = false;
 	ctx->mm = current->mm;
 	/* prevent the mm struct to be freed */
 	mmgrab(ctx->mm);
diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index 50f7302..83325d3 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -36,10 +36,12 @@
 extern int handle_userfault(struct vm_fault *vmf, unsigned long reason);
 
 extern ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
-			    unsigned long src_start, unsigned long len);
+			    unsigned long src_start, unsigned long len,
+			    bool *mmap_changing);
 extern ssize_t mfill_zeropage(struct mm_struct *dst_mm,
 			      unsigned long dst_start,
-			      unsigned long len);
+			      unsigned long len,
+			      bool *mmap_changing);
 
 /* mm helpers */
 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 6c1a863..1367583 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -439,7 +439,8 @@
 					      unsigned long dst_start,
 					      unsigned long src_start,
 					      unsigned long len,
-					      bool zeropage)
+					      bool zeropage,
+					      bool *mmap_changing)
 {
 	struct vm_area_struct *dst_vma;
 	ssize_t err;
@@ -466,6 +467,15 @@
 	down_read(&dst_mm->mmap_sem);
 
 	/*
+	 * 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
+	 */
+	err = -EAGAIN;
+	if (mmap_changing && READ_ONCE(*mmap_changing))
+		goto out_unlock;
+
+	/*
 	 * Make sure the vma is not shared, that the dst range is
 	 * both valid and fully within a single existing vma.
 	 */
@@ -596,13 +606,15 @@
 }
 
 ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
-		     unsigned long src_start, unsigned long len)
+		     unsigned long src_start, unsigned long len,
+		     bool *mmap_changing)
 {
-	return __mcopy_atomic(dst_mm, dst_start, src_start, len, false);
+	return __mcopy_atomic(dst_mm, dst_start, src_start, len, false,
+			      mmap_changing);
 }
 
 ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start,
-		       unsigned long len)
+		       unsigned long len, bool *mmap_changing)
 {
-	return __mcopy_atomic(dst_mm, start, 0, len, true);
+	return __mcopy_atomic(dst_mm, start, 0, len, true, mmap_changing);
 }