How to report bugs (Re: 6.2-STABLE deadlock?)

On Wed, Apr 25, 2007 at 10:53:08AM +0800, LI Xin wrote:
Hi, Oleg,

Oleg Derevenetz wrote:
??????? LI Xin <delphij@xxxxxxxxxxx>:
[...]
I'm not very sure if this is specific to one disk controller. Actually
I got some occasional reports about similar hangs on amd64 6.2-RELEASE
(slightly patched version) that most of processes stuck in the 'ufs'
state, under very light load, the box was equipped with amr(4) RAID.

I was not able to reproduce the problem at my lab, though, it's still
unknown that how to trigger the livelock :-( Still need some
investigate on their production system.

I reported simular issue for FreeBSD 6.2 in audit-trail for kern/104406:

http://www.freebsd.org/cgi/query-pr.cgi?pr=104406&cat=

and there should be a thread related to this. Briefly, I suspects that this is
related to nullfs filesystems on my server and when I cvsuped to FreeBSD 6.2-
STABLE with Daichi's unionfs-related patches and replaced nullfs-mounted fs
with unionfs-mounted (that was done 10.03.07) problem is gone (seems to be so,
at least).

Hmm... Seems to be different issues. The problem I have received was a
pgsql server (no nullfs/unionfs involved), and the hang always happen
when it is not being heavily loaded (usually in the morning, for
instance, and there is no special configuration, like scheduled tasks
which can generate disk load, etc., only the entropy harvesting), so
this is quite confusing.

Yes, a large part of the confusion is the unfortunate tendency of
people to do the following:

<user1> my system hangs/panics/etc
<user2> my system hangs/panics/etc too; it must be the same problem!

What we really need is for every FreeBSD user who encounters a
hang/panic/etc to avoid jumping to conclusions -- no matter how many
superficial similarities there may seem to you -- and instead go
through the relevant steps described here:

http://www.freebsd.org/doc/en_US.ISO8859-1/books/developers-handbook/kerneldebug.html

Until you (or a developer) have analyzed the resulting information,
you cannot definitively determine whether or not your problem is the
same as a given random other problem, and you may just confuse the
issue by making claims of similarity when you are really reporting a
completely separate problem.

Thanks,
Kris

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