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

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Date:	Thu, 17 Sep 2009 14:59:02 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Eric Paris <eparis@...hat.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, 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.

Maybe linux-hotplug (added to cc) already knows about this issue?
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