Hi Xin,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v4.19-rc3 next-20180913]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/My-Name/kernel-prevent-submission-of-creds-with-higher-privileges-inside-container/20180915-051650
config: i386-tinyconfig (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

   kernel/cred.o: In function `commit_creds':
>> cred.c:(.text+0x1ae): undefined reference to `get_net_ns_by_pid'

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0-DAY kernel test infrastructure                Open Source Technology Center
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