Stress-ng test lockf hangs with Graphene

[jinengandhi-intel]

Description of the problem

Description of lockf test

start  N workers that randomly lock and unlock regions of a file
#   using the POSIX lockf(3) locking mechanism. Each worker  creates
#   a  64  KB file and attempts to hold a maximum of 1024 concurrent
#   locks with a child process that also tries to hold 1024  concur‐
#   rent  locks.  Old  locks  are  unlocked in a first-in, first-out
#   basis.

Link to the lockf stress-ng test source code: https://github.com/ColinIanKing/stress-ng/blob/master/stress-lockf.c

This test when run under Graphene hangs for any number of stressors. I have attached the logs for lockf running with 8 stressors as well as 1 stressor.
lockf_8stressor.log
lockf_1stressor.log

Steps to reproduce

Commands to run the lockf stressor

graphene-direct stress-ng --lockf 1 --timeout 60s 
graphene-direct stress-ng --lockf 8 --timeout 60s 

Expected results

Actual results

[dimakuv]

@pwmarcz This will be interesting for you. That's a cool stress test for your F_SETLK implementation in Graphene.

[pwmarcz]

I will take a look. One big limitation of the current locks is that they're uninterruptible, that might be it.