Date: Wed, 25 Apr 2007 12:14:20 +0400 (MSD) From: Oleg Derevenetz <oleg@vsi.ru> To: Kris Kennaway <kris@obsecurity.org> Cc: freebsd-stable@freebsd.org, LI Xin <delphij@delphij.net>, Oleg Derevenetz <oleg@vsi.ru> Subject: Re: How to report bugs (Re: 6.2-STABLE deadlock?) Message-ID: <1177488860.462f0ddc6ce8c@webmail.vsi.ru> In-Reply-To: <20070425035316.GB44054@xor.obsecurity.org> References: <20070313140848.GA89182@steerpike.hanley.stade.co.uk> <20070423025631.GA33256@steerpike.hanley.stade.co.uk> <20070423113912.GE2052@deviant.kiev.zoral.com.ua> <462DDB4D.8080507@delphij.net> <1177442585.462e5919c71f0@webmail.vsi.ru> <462EC294.3040001@delphij.net> <20070425035316.GB44054@xor.obsecurity.org>
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Цитирую Kris Kennaway <kris@obsecurity.org>: > > Oleg Derevenetz wrote: > > > ??????? LI Xin <delphij@delphij.net>: > > [...] > > >> 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. Not all people can do deadlock debugging, though. In my case turning on INVARIANTS and WITNESS leads to unacceptable performance penalty due to heavily loaded server. So I can only describe my case, actions and result without providing any debug information.
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