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Date: Mon, 7 Jan 2008 22:14:26 +0100 (CET) From: "Brice Figureau" <brice+lklm@...sofwonder.com> To: "Randy Dunlap" <randy.dunlap@...cle.com> Cc: linux-kernel@...r.kernel.org Subject: Re: Strange freeze on 2.6.22 (deadlock?) On Mon, January 7, 2008 20:06, Brice Figureau wrote: > > On Mon, January 7, 2008 18:20, Randy Dunlap wrote: >> On Mon, 07 Jan 2008 16:48:54 +0100 Brice Figureau wrote: >> >>> Hi, >>> >>> I'm seeing a strange complete server freeze/lock-up on an bi-Xeon HT >>> amd64 server running standard debian 2.6.22 (and before that vanilla >>> 2.6.19.x and 2.6.20.x which exhibited the same issue). >>> >>> I'm only reporting it now, since I could get a full sysrq-t only this >>> morning. >>> >>> The symptoms are that every 5 to 7 days, the server (which acts as a MX >>> along with a few low traffic websites) locks-up. The ipmi watchdog is >>> unable to reboot the server (and doesn't even trigger, since there is >>> no >>> evidence in the esmlog), the machine is still pingable. I can't ssh to >>> it, but I can enter my login & password on a serial console, but no >>> shell is started. >>> >>> Pressing sysrq-t produced the trace hosted here: >>> http://www.daysofwonder.com/bug/crash-server1.txt.gz >>> >>> It happened one time when I was connected to the server through ssh and >>> I could see that the load started to increase well above 100. It was >>> then impossible to launch new process from the command-line (and I had >>> to reboot manually). >>> It happened also last week, and the server was stuck for about 6 hours. >>> When I started investigating what was wrong, it slowly came back to >>> life >>> (with an avg 1-min load of more than 1500, and tons of cron processes >>> running in parallel). >>> >>> I'm not really familiar with kernel development so I can't really find >>> the issue in the aforementioned trace output. >>> What I think is that for some reason there is a race/deadlock that >>> finally prevents new processes to really start (which in turns produces >>> the high load). >>> >>> What seems suspect in the aforementioned trace is: >>> *) lot of processes stacktrace ends in __mod_timer+0xc3/0xd3 >>> which seems to be this line from kernel/timer.c >>> >>> 415 timer->expires = expires; >>> 416 internal_add_timer(base, timer); >>> --> spin_unlock_irqrestore(&base->lock, flags); >>> >>> 419 return ret; >>> 420 } >>> >>> *) lot of processes stacktrace ends in __mutex_lock_slowpath and/or >>> zone_statistics >> >> There are also lots of processes in D state (usually waiting >> for I/O to complete). And jbd is in their stack traces. >> >> How is/are the ext3 filesystems mounted? I mean what data=xyz >> mode? data=journal (the heaviest duty mode) has at least one >> known deadlock. If you are using data=journal, you could try >> switching to data=ordered... > > Thanks for the answer. > I'm using whatever is the default mount option (which I think is > data=ordered). The only other mount option I use is nodiratime,noatime. I'm sorry, I stand corrected, there is a data=journal option but not on a mount point, as an attribute of a bunch of directories (postfix queues): # lsattr /var/spool/postfix/ -------A-----j---- /var/spool/postfix/active -------A-----j---- /var/spool/postfix/bounce -------A-----j---- /var/spool/postfix/corrupt -------A-----j---- /var/spool/postfix/defer -------A-----j---- /var/spool/postfix/deferred -------A-----j---- /var/spool/postfix/flush -------A-----j---- /var/spool/postfix/hold -------A-----j---- /var/spool/postfix/incoming -------A-----j---- /var/spool/postfix/private -------A-----j---- /var/spool/postfix/maildrop -------A-----j---- /var/spool/postfix/public -------A-----j---- /var/spool/postfix/pid -------A-----j---- /var/spool/postfix/saved -------A-----j---- /var/spool/postfix/trace The idea was that queue file are short-lived files and thus they could only be stored in the journal and never hit the regular data area. So I might have hit the deadlock you were talking about. I just disabled this setup, we'll see if that changes anything. Note that I was using this setup since 2.4 time, the problem appeared only a few kernel revisions ago (around 2.6.18 I think). Thanks -- Brice Figureau -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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