Re: tmpfs race conditions

[christos%zoulas.com@localhost (Christos Zoulas)]

On Dec 22,  4:45pm, dholland-tech%netbsd.org@localhost (David Holland) wrote:
-- Subject: Re: tmpfs race conditions

| On Tue, Dec 22, 2015 at 04:15:47PM +0000, Christos Zoulas wrote:
|  > 1. Do we have a PR for the MFS umount hang?
| 
| Don't think so.
| 
|  > 2. Do we have a PR for the TEMPFS race?
| 
| No. Unless it turns out to be the same as some old existing problem;
| but it seems to have appeared only within the last few months.

That sounds really nasty.

| If it's not actually tmpfs-specific, I wonder if there's some uvm op
| missing from some vnode recycling path.

Any ideas how to reproduce it? I am thinking of something like: have a
producer thread create files with sequential names and a consumer thread
that gets notified when each file (or n files) have been created, tests
if they exist and remove them. Any better ideas?

christos