Subject: Re: 7GB memtest causes hard system hang.
To: None <firstname.lastname@example.org>
From: Greg Oster <email@example.com>
Date: 01/16/2006 11:33:08
Thor Lancelot Simon writes:
> The message you quoted _most of_ described exactly how to reproduce the
> problem. Boot a 3.0 GENERIC.MP kernel on a dual-Opteron system with 8GB
> of RAM. Next, unlimit datasize, memoryuse, and memorylocked.
> run "memtester" from pkgsrc -- I see I accidentally called it "memtest",
> but since that's the only memory tester we have that runs under NetBSD
> and it's also the one everyone uses, I hardly think that's too hard to
> figure out -- specifying a 7GB test size;
So running 'memtester 7500' gave me:
memtester version 4.0.5 (64-bit)
Copyright (C) 2005 Charles Cazabon.
Licensed under the GNU General Public License version 2 (only).
pagesize is 4096
pagesizemask is 0xfffffffffffff000
want 7500MB (7864320000 bytes)
got 7500MB (7864320000 bytes), trying mlock ...failed for unknown reason.
Continuing with unlocked memory; testing will be slower and less reliable.
Stuck Address : testing 0
and seemed to be working:
661 root -5 0 7500M 7176M biowai/3 0:30 4.25% 4.25% memtester
at least for the kernel I was running at the time (more below)...
> it's the only command line option
> memtester takes, and it's mandatory. Next, watch your system hang so hard
> that you can't get it to drop to DDB.
I initially ran this with a kernel where I've tweaked
in the kernel config, and couldn't reproduce the problem at all.
When I actually paid a bit more attention to the details, and ran
a GENERIC.MP kernel, here's the panic I get on the console:
panic: pmap_enter: no pv entries available
with no opportunity to drop to ddb or anything.
(Without the "options NKMEMPAGES=150000" tweak, the machine is basically
useless to me -- I can easily run "too much stuff" that gets me to the
"no pv entries available" panic :( )
The proper fix is to fix the pmap code. A short-term workaround is to
do the NKMEMPAGES bump above...