[josef-btrfs:blk-iolatency 6/13] common.c:undefined reference to `blkcg_maybe_throttle_current'

[kbuild test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/josef/btrfs-next.git 
blk-iolatency
head:   6bbc4451bcc7359b14e190615ff671fd63e34d62
commit: 605adede5ce998f9e834c1783e74dc0660b346db [6/13] blkcg: add generic 
throttling mechanism
config: i386-tinyconfig (attached as .config)
compiler: gcc-7 (Debian 7.3.0-16) 7.3.0
reproduce:
        git checkout 605adede5ce998f9e834c1783e74dc0660b346db
        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

   arch/x86/entry/common.o: In function `prepare_exit_to_usermode':
>> common.c:(.text+0x139): undefined reference to `blkcg_maybe_throttle_current'

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.config.gz
Description: application/gzip