diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index 75298d3358e7..08eec0b691b0 100644
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -136,6 +136,7 @@ extern int os_ioctl_generic(int fd, unsigned int cmd, unsigned long arg);
 extern int os_get_ifname(int fd, char *namebuf);
 extern int os_set_slip(int fd);
 extern int os_mode_fd(int fd, int mode);
+extern int os_fsync_file(int fd);
 
 extern int os_seek_file(int fd, unsigned long long offset);
 extern int os_open_file(const char *file, struct openflags flags, int mode);
diff --git a/arch/um/kernel/physmem.c b/arch/um/kernel/physmem.c
index f116db15d402..30fdd5d0067b 100644
--- a/arch/um/kernel/physmem.c
+++ b/arch/um/kernel/physmem.c
@@ -103,6 +103,7 @@ void __init setup_physmem(unsigned long start, unsigned long reserve_end,
 	 */
 	os_seek_file(physmem_fd, __pa(&__syscall_stub_start));
 	os_write_file(physmem_fd, &__syscall_stub_start, PAGE_SIZE);
+	os_fsync_file(physmem_fd);
 
 	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 07a750197bb0..08d90fba952c 100644
--- a/arch/um/os-Linux/file.c
+++ b/arch/um/os-Linux/file.c
@@ -237,6 +237,12 @@ void os_close_file(int fd)
 {
 	close(fd);
 }
+int os_fsync_file(int fd)
+{
+	if (fsync(fd) < 0)
+	    return -errno;
+	return 0;
+}
 
 int os_seek_file(int fd, unsigned long long offset)
 {