Hi Christian,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on net-next/master]

url:    https://github.com/0day-ci/linux/commits/Christian-Brauner/netns-uevent-performance-tweaks/20180420-013717
config: alpha-alldefconfig (attached as .config)
compiler: alpha-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=alpha 

All errors (new ones prefixed by >>):

   kernel/ksysfs.o: In function `uevent_seqnum_show':
>> (.text+0x18c): undefined reference to `get_ns_uevent_seqnum_by_vpid'
   (.text+0x19c): undefined reference to `get_ns_uevent_seqnum_by_vpid'

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