Messages in this thread | | | Subject | Strange freeze on 2.6.22 (deadlock?) | From | Brice Figureau <> | Date | Mon, 07 Jan 2008 16:48:54 +0100 |
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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
Anyway, I will soon reboot to a 2.6.23.x to see if that symptom persists. More information (config, server specs) are available on request.
I'm not subscribed to the list, so please CC: me for any anwser. Many thanks, -- Brice Figureau <brice+lklm@daysofwonder.com>
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