diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index b314cf7..e984b2c 100644
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -144,6 +144,7 @@ extern int os_write_file(int fd, const void *buf, int count);
 extern int os_file_size(const char *file, unsigned long long *size_out);
 extern int os_file_modtime(const char *file, unsigned long *modtime);
 extern int os_pipe(int *fd, int stream, int close_on_exec);
+extern int os_fsync(int fd);
 extern int os_set_fd_async(int fd);
 extern int os_clear_fd_async(int fd);
 extern int os_set_fd_block(int fd, int blocking);
diff --git a/arch/um/kernel/physmem.c b/arch/um/kernel/physmem.c
index f116db1..ea606ee 100644
--- a/arch/um/kernel/physmem.c
+++ b/arch/um/kernel/physmem.c
@@ -87,6 +87,14 @@ void __init setup_physmem(unsigned long start, unsigned long reserve_end,
 
 	physmem_fd = create_mem_file(len + highmem);
 
+	/*
+	 * Special kludge - This page will be mapped in to userspace processes
+	 * from physmem_fd, so it needs to be written out there.
+	 */
+	os_seek_file(physmem_fd, __pa(&__syscall_stub_start));
+	os_write_file(physmem_fd, &__syscall_stub_start, PAGE_SIZE);
+        os_fsync(physmem_fd);
+
 	offset = uml_reserved - uml_physmem;
 	err = os_map_memory((void *) uml_reserved, physmem_fd, offset,
 			    len - offset, 1, 1, 1);
@@ -97,12 +105,6 @@ void __init setup_physmem(unsigned long start, unsigned long reserve_end,
 		exit(1);
 	}
 
-	/*
-	 * Special kludge - This page will be mapped in to userspace processes
-	 * from physmem_fd, so it needs to be written out there.
-	 */
-	os_seek_file(physmem_fd, __pa(&__syscall_stub_start));
-	os_write_file(physmem_fd, &__syscall_stub_start, PAGE_SIZE);
 
 	bootmap_size = init_bootmem(pfn, pfn + delta);
 	free_bootmem(__pa(reserve_end) + bootmap_size,
diff --git a/arch/um/os-Linux/file.c b/arch/um/os-Linux/file.c
index b049a63..d4985be99 100644
--- a/arch/um/os-Linux/file.c
+++ b/arch/um/os-Linux/file.c
@@ -33,6 +33,10 @@ static void copy_stat(struct uml_stat *dst, const struct stat64 *src)
 	});
 }
 
+int os_fsync(int fd) {
+   fsync(fd);
+}
+
 int os_stat_fd(const int fd, struct uml_stat *ubuf)
 {
 	struct stat64 sbuf;