linux-kernel - Re: kernel panic - not syncing: out of memory and no killable processes

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Message-Id: <1253285923.30531.17.camel@dhcp231-106.rdu.redhat.com>
Date:	Fri, 18 Sep 2009 10:58:43 -0400
From:	Eric Paris <eparis@...hat.com>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Greg KH <greg@...ah.com>, linux-hotplug@...r.kernel.org
Subject: Re: kernel panic - not syncing: out of memory and no killable
 processes

On Thu, 2009-09-17 at 14:59 -0700, David Rientjes wrote:
> On Thu, 17 Sep 2009, Eric Paris wrote:
> 
> > Absolutely 100% udevd related.  It always pops right when udev starts.
> > Every time.  I don't know how to get that to come out on the serial
> > port, you only get to see the kernel messages (although there is nothing
> > on the screen other than "Starting udev"
> > 
> > Reverting 3f2aa307c4d26b4ed6509d0a79e8254c9e07e921 causes the problem to
> > go away.  I now am running a 79b520e87e kernel + your patch (adding
> > console_verbose()) + reverting 3f2aa307c4d2 and it seems to be working.
> > 
> 
> Isolating udevd down to an interactivity scheduling change isn't _that_ 
> bizarre.  I think the setting of UDEVD_PRIORITY is already mostly 
> arbitrary anyway and it'll allow 192 children on your 512M machine by 
> default unless you changed UDEVD_MAX_CHILDS for uid 0.
> 
> The default timeout for idle workers is 3 seconds, which may just happen 
> to be long enough to panic your machine because of low memory.  If that's 
> the case, I don't believe that it's a scheduler issue but rather a root 
> abuse of setting all udevd threads to be OOM_DISABLE.
> 
> What is your udevd --version?  The latest is udev-146 released last month.

145

Let me try and clone the vm some I don't break my reproducer.  I'll see
if adding more memory fixes it.  Doesn't look like Fedora has built a
-146 yet, I'll see if I can get one of those as well.

udev bug, configuration issue, whatever, or not, it's a regression that
I used to be able to boot and updating my kernel leaves me unable to
boot.  I think we all agree when 512M of memory isn't enough to boot to
runlevel 3 we've got a problem   :)

-Eric


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