[bug report] OOM caused by mlock() during exiting blktrace

[Ming Lei <tom.leiming@xxxxxxxxx>]

Hello Guys,

It is observed that nr_cpu * mlock(128M) is called when exiting
'blktrace -b 8192 -d $DEV'. And OOM is easily triggered when the
machine has lots of CPU cores.

So can we figure out one way to not lock big buffer for avoiding
OOM?

-- 
Ming Lei