Hello,

syzbot has tested the proposed patch but the reproducer still triggered  
crash:
no output from test machine



Tested on  
git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu.git/master commit
7928b2cbe55b2a410a0f5c1f154610059c57b1b2 (Sun Feb 11 23:04:29 2018 +0000)
Linux 4.16-rc1

compiler: gcc (GCC) 7.1.1 20170620
Patch is attached.
Kernel config is attached.
Raw console output is attached.