Possible bug in or around posix_fadvise after r292326

[Benno Rice]

> On Jan 4, 2016, at 22:05, Benno Rice <benno at freebsd.org> wrote:
> 
> Hi Konstantin,
> 
> I recently updated my dev box to r292962. After doing this I attempted to set up PostgreSQL 9.4. When I ran initdb the last phase hung. Using procstat -kk I found it appeared to be stuck in a loop inside a posix_fadvise syscall. I could not ^C or ^Z the initdb process. I could kill it but a subsequent attempt to rm -rf the /usr/local/pgsql/data directory also got stuck and was unkillable by any means. Rebooting allowed me to remove the directory but the initdb process still hung when I re-ran it.

[snip]

> 
> I haven’t managed to dig any deeper than that yet.
> 
> Is there any other information I could give you to help narrow this down?

Rebooted with a WITNESS kernel and got the following LOR after initdb started:

https://gist.github.com/jeamland/69a07c4523f0dea4c26c <https://gist.github.com/jeamland/69a07c4523f0dea4c26c>