Page fault, GEOM problem??

[Johan Ström]

Hi!

On 18 nov 2005, at 18.43, Xin LI wrote:

> Hi, Johan,
>
> On 11/18/05, Johan Ström <johan at stromnet.org> wrote:
>> On 18 nov 2005, at 10.17, Xin LI wrote:
> [snip]
>> Doesnt look like I got any "usable" dump devices..
>> When booting i get
> [...]
>> Loading configuration files.
>> No suitable dump device was found.
>> Entropy harvesting:
>> interrupts
>> ethernet
>> point_to_point
>> kickstart
>> .
>> swapon: adding /dev/mirror/gm0s1b as swap device
>
> I see, so your both SATA disks are in the same mirror group...
>
>> Then naturally:
>> /etc/rc: WARNING: Dump device does not exist.  Savecore not run.
>>
>> Looked around in the rc-scripts and tried to figure out what it did,
>> the dumpon script
>> tries to autolookup a good dump device but finds none..
>
> Unfortunately, kernel dumps currently does not support every device,
> for some technical reasons (probably to simplify the crash code so
> they do not make more mistakes^Wdamages)
>
>> According to the page you linked to, the dumpon command has to be
>> executed AFTER swapon.. Why is the rc scripts trying to run it before
>> swapon then?
>
> I guess this is because that dumpon now can detect dump device
> automatically, but I'm not quite sure about this.  Will look for the
> reason.  I think either Handbook should be updated, or the code should
> be corrected.
>
> What I am very curious is that why dumpon is "BEFORE" savecore.  Maybe
> I have some misunderstanding...

Sorry, partly my misstake.. I think i missunderstod how save savecore  
works below (when i tried it manually in last mail)..
But the messages from above are directly from boot, seems it tries  
dumpon before savecore? Relevant bootlog from last boot:


ad0: 2441MB <WDC AC22500L 32.41N35> at ata0-master UDMA33
acd0: CDROM <CD-ROM CDU701-F/1.0q> at ata1-master PIO4
ad6: 286188MB <Maxtor 7L300S0 BANC1G10> at ata3-master SATA150
ad10: 286188MB <Maxtor 7L300S0 BANC1G10> at ata5-master SATA150
GEOM_MIRROR: Device gm0s1 created (id=4118114647).
GEOM_MIRROR: Device gm0s1: provider ad6s1 detected.
GEOM_MIRROR: Device gm0s1: provider ad10s1 detected.
GEOM_MIRROR: Device gm0s1: provider ad10s1 activated.
GEOM_MIRROR: Device gm0s1: provider ad6s1 activated.
GEOM_MIRROR: Device gm0s1: provider mirror/gm0s1 launched.
Trying to mount root from ufs:/dev/mirror/gm0s1a
Loading configuration files.
dumpon: (this DIOCSKERNELDUMP message is probably since i specified  
dumpdev in rc.conf so it forced useage of gm0s1b instead of letting  
the scripts autodetect.. )
ioctl(DIOCSKERNELDUMP)
:
Operation not supported
Entropy harvesting:
interrupts
ethernet
point_to_point
kickstart
.
swapon: adding /dev/mirror/gm0s1b as swap device
Starting file system checks:
/dev/mirror/gm0s1a: FILE SYSTEM CLEAN; SKIPPING CHECKS
/dev/mirror/gm0s1a: clean, 213811 free (771 frags, 26630 blocks, 0.3%  
fragmentation)
/dev/mirror/gm0s1e: FILE SYSTEM CLEAN; SKIPPING CHECKS
/dev/mirror/gm0s1e: clean, 1012917 free (85 frags, 126604 blocks,  
0.0% fragmentation)
/dev/mirror/gm0s1f: FILE SYSTEM CLEAN; SKIPPING CHECKS
/dev/mirror/gm0s1f: clean, 115955787 free (40747 frags, 14489380  
blocks, 0.0% fragmentation)
/dev/mirror/gm0s1d: FILE SYSTEM CLEAN; SKIPPING CHECKS
/dev/mirror/gm0s1d: clean, 1983354 free (4834 frags, 247315 blocks,  
0.2% fragmentation)
<ifconfig stuff>
Starting devd.
Mounting NFS file systems:
.
Creating and/or trimming log files:
.
Starting syslogd.
Checking for core dump on /dev/mirror/gm0s1b...
savecore: no dumps found
Starting named.
<rest of boot>

So, it seems it does run savecore after running dumpon and mounting  
disks etc... Is that wrong?

>
>> Anyway, tried to do dumpon manually on my swap drive:
>>
>> $ dumpon -v /dev/mirror/gm0s1b
>> dumpon: ioctl(DIOCSKERNELDUMP): Operation not supported
>>
>> Didn't work too good..
>> Also tried savecore manually:
>>
>> $ savecore /var/crash/ /dev/mirror/gm0s1b
>> savecore: no dumps found

(This was my misstake, of course there are no dumps when I didnt have  
a dump when it crashed..)

>>
>> Didnt work very good either (but probably expected since there was no
>> working dumps..)
>> Google showed me some other thread in this list about gmirror swap
>> dump, just a question (if it was supported) w/o any answers tho. Same
>> error as I got.
>
> It seems that this could not be workaround'ed easily.  If possible, my
> suggestion is that you attach a third disk and create a swap partition
> on it for the crash dump.  If this is not feasible, then adding DDB
> and KDB may give us a chance to catch the panic and you can use
> "trace" command at the ddb> prompt to obtain a simplified backtrace,
> and there is good chance that it would reveal what is happening.
>
> I have cc'ed to Pawel who is very knowledgeable in this area, and
> let's see whether he has some better suggestions :-)

Okay, just added an old but working 2 gig disk to the system, made it  
a swap and swapon'ed and:

root at elfi:~$ dumpon -v /dev/ad0s1b
kernel dumps on /dev/ad0s1b

Great! :) So, let's see when/if it dies next time... Before I took it  
down for the dump-disk, it had been running fine
for 1d 1h (since boot after crasch), however probably not as loaded  
as the day it crashed.. I'll try to load it some now and see if it  
crashes.

Thanks

Johan

>
> Cheers,
> --
> Xin LI <delphij at delphij.net> http://www.delphij.net