I have another application that consumes all of the huge pages; they aren't for pgsql. :) I've modified the configuration file from "try" to "off" and munmap is no more. Mischief managed.
Thanks for your help.
On Tue, Oct 11, 2016 at 6:15 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
No problem. I'm starting to think that this isn't actually a Postgres bug, but rather something funny with your kernel. The code in sysv_shmem is certainly as fragile as can be, but I'm darned if I can find an existing code path that would actually break it --- and the lack of other complaints is pointing towards something funny with your system, too.
First off, does changing "huge_pages" in postgresql.conf alter the behavior? (It defaults to "try", see what happens with "on" or "off".)
Second, I notice that you've got
> Hugepagesize: 1048576 kB
which is just enormous. PG is only going to request circa 140MB given the settings you mentioned. We've seen reports of kernel bugs that cause mmap() to fail for requests that aren't a multiple of the hugepage size, but I've not heard that mmap() might succeed and then munmap() fail. That seems like what's happening to you though.