Re: BUG: sleeping function called from invalid context atkernel/mutex.c:271

From: Paul E. McKenney
Date: Wed Apr 18 2012 - 09:52:42 EST


On Wed, Apr 18, 2012 at 08:08:46AM -0400, Steven Rostedt wrote:
> On Wed, 2012-04-18 at 10:51 +0600, Alexander E. Patrakov wrote:
>
> > > >
> > > > Hmm, this can also be reported if you have an rcu leak. Which would also
> > > > explain your memory leak. RCU is the kernel's "garbage collector" and if
> > > > it gets stuck, then you will definitely start seeing memory leaks, as
> > > > memory wont be freed.
> > >
> > > If RCU is stuck, you should see RCU CPU stall warnings, which can
> > > give clues as to what is causing RCU to get stuck.
> >
> > Yes, there were such warnings, but all of them said that the stall ended
> > before dump start. So nothing reportable here, but I have just found
> > that https://bugzilla.novell.com/show_bug.cgi?id=754186 looks quite
> > similar in the sense that it (and duplicates) also has undumpable stalls
> > of increasing length, and IPv6 is in use both at home and at work.
> >
>
> Do you see the RT throttling message too? That's a bug with an RT task
> going haywire. If that is happening, an RT task may be preventing an RCU
> grace period to finish, and causing the RCU stalls.

Hmmm... Maybe I should revisit running the RCU core processing in
real-time kernel threads... Though it was quite painful the last time
I tried that.

Thanx, Paul

> Just because they ended, doesn't mean that the problem went a way. If
> RCU is being blocked, you will start to see memory leaks. As I said, RCU
> works as the kernels garbage collector. If it stops or just slows down
> significantly, memory does not get freed.
>
> -- Steve
>
>
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