Re: [vserver] [resend] vs2.2.0.x and scheduler getting stuck

From: Grzegorz Nosek <grzegorz.nosek_at_gmail.com>
Date: Sat 17 May 2008 - 16:57:59 BST
Message-ID: <121a28810805170857k73ea8er46b73b40fd228243@mail.gmail.com>

2008/5/17 Daniel Hokka Zakrisson <daniel@hozac.com>:
> Grzegorz Nosek wrote:
>> Hi all,
>>
>> (sorry if you receive this message twice)
>>
>> I've been experiencing some weird hangs (boom and it's dead, no panic,
>> not even a softlockup or lockdep warning). It happens about once a month
>> (of course, in production only), usually under some load (I suspected
>> I/O but it might be simple CPU usage too). It happened on several very
>> different machines (2-way pentium3, 4-way opteron 270).
>>
>> After enabling the nmi watchdog I could trace it back to schedule(), or
>> at least the nmi watchdog felt the need to kill the machine right in the
>> middle of a schedule() call.
>
> So I guess it can happen on vanilla kernels as well... This was noticed
> and fixed on PlanetLab, and the patches are already fed upstream (see
> http://vserver.13thfloor.at/Experimental/delta-sched-fix0{4,5,6}.diff), to
> be included in the next release.

The fix06.diff patch looks like a proper fix, although (guessing) it
could still lock the scheduler when all contexts are paused (is this
even possible? probably not).

I'm not really sure how it can happen on vanilla kernels, as it's a
loop added by the vserver patch (both the label and the goto). Care to
enlighten me? :)

Best regards,
 Grzegorz Nosek
Received on Sat May 17 16:58:15 2008

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