因为内核里有很多编译参数，所以需要配置下。

可以参考 http://ybin.cc/tools/clion-for-linux-driver-developer/

我的最终配置是：

...
include_directories(../kernel-3.10.0-327.36.1.el7/linux-3.10.0-327.36.1.el7/include)
include_directories(../kernel-3.10.0-327.36.1.el7/linux-3.10.0-327.36.1.el7/include/linux)
include_directories(../kernel-3.10.0-327.36.1.el7/linux-3.10.0-327.36.1.el7/mm)
include_directories(../kernel-3.10.0-327.36.1.el7/linux-3.10.0-327.36.1.el7/arch/x86/include)
include_directories(../kernel-3.10.0-327.36.1.el7/linux-3.10.0-327.36.1.el7/include/uapi)
include_directories(../kernel-3.10.0-327.36.1.el7/linux-3.10.0-327.36.1.el7/arch/x86/include/uapi)
include_directories(.)
include_directories(drbd)
include_directories(drbd/compat)
include_directories(drbd/linux)

add_definitions(-imacros ../kernel-3.10.0-327.36.1.el7/linux-3.10.0-327.36.1.el7/include/linux/kconfig.h)
add_definitions(-D__KERNEL__)
add_definitions(-DKBUILD_MODNAME)
add_definitions(-DCONFIG_BLOCK)
add_definitions(-DCONFIG_HZ)
add_definitions(-DMODULE)
add_definitions(-std=gnu89)
...