Re: REL_11_STABLE: dsm.c - cannot unpin a segment that is not pinned

On Mon, Feb 18, 2019 at 9:35 AM Justin Pryzby <pryzby(at)telsasoft(dot)com> wrote:
> On Mon, Feb 18, 2019 at 09:26:53AM +1300, Thomas Munro wrote:
> > Huh. What exactly do you mean by "killing the postmaster"? If you
> > mean SIGKILL or something, one problem with 11 is that
>
> I mean unqualified /bin/kill which is kill -TERM (-15 in linux).
>
> I gather (pun acknowledged but not intended) you mean "one problem with PG v11"
> and not "one problem with kill -11" (which is what I first thought, although I
> was somehow confusing kill -9, and since I don't know why anyone would ever
> want to manually send SIGSEGV).
>
> I think you're suggesting that's a known issue with v11, so nothing to do.

Yeah. I suppose we should probably consider back-patching a fix for that.

I've pushed the second DSM fix. Here is a summary of the errors you
(and others) have reported, for the benefit of people searching the
archives. I will give the master commit IDs, but the fixes should be
in 11.3 and 10.8.

1. "dsa_allocate could not find %zu free pages": freepage.c, fixed in 7215efdc.
2. "dsa_area could not attach to segment": dsm.c, fixed in 6c0fb941.
3. "cannot unpin a segment that is not pinned": dsm.c, fixed in 0b55aaac.

That resolves all the bugs I'm currently aware of in this area.
(There is still the question of whether we should change the way DSA
cleans up to avoid a self-deadlock on recursive error, but that needs
some more thought.)

--
Thomas Munro
http://www.enterprisedb.com