Re: 9.4 beta1 crash on Debian sid/i386

Christoph Berg <cb(at)df7cb(dot)de> writes:
> Re: Andres Freund 2014-05-18 <20140518091445(dot)GU23662(at)alap3(dot)anarazel(dot)de>
>> Did you measure how large the stack actually was when you got the
>> SIGBUS? Should be possible to determine that by computing the offset
>> using some local stack variable in one of the depeest stack frames.

> Looking at /proc/*/maps, the stack is ffb38000-ffd1e000 = 1944kB for a
> process that just got SIGBUS. This seems to be in line with
> stack_base_ptr = 0xffd1c317 and the fcinfo address in

OK, so the problem is that getrlimit(RLIMIT_STACK) is lying to us about
the available stack depth. I'd classify that as a kernel bug. I wonder
if it's a different manifestation of this issue:
https://bugzilla.redhat.com/show_bug.cgi?id=952946

A different line of thought is that if ulimit -s is 8192, why are we
not getting 8MB of stack? But in any case, if we're only going to
get 1944kB, getrlimit ought to tell us that.

regards, tom lane