Re: [percpu] BUG: unable to handle kernel NULL pointer dereference at (null)

[Fengguang Wu]

On Thu, Sep 04, 2014 at 09:04:28AM -0700, Paul E. McKenney wrote:
> On Thu, Sep 04, 2014 at 08:38:45PM +0800, Fengguang Wu wrote:
> > On Tue, Sep 02, 2014 at 10:16:57AM -0700, Paul E. McKenney wrote:
> > > On Tue, Sep 02, 2014 at 11:55:58AM -0500, Christoph Lameter wrote:
> > > > On Tue, 2 Sep 2014, Paul E. McKenney wrote:
> > > > 
> > > > > Added by ac1bea85781e (sched,rcu: Make cond_resched() report RCU quiescent
> > > > > states), removed by 4a81e8328d379 (rcu: Reduce overhead of cond_resched()
> > > > > checks for RCU).  So, as you say, no effect on contemporary kernels.
> > > > 
> > > > Well not sure what to make out of all of this....
> > > 
> > > Yep, still confused as to how the patch adding the definition could have
> > > caused a failure.  Fengguang, any thoughts?
> > 
> > Yeah this is confusing.. I checked carefully and find that commit
> > 0e98023 and afea227 are built on 2 quite different servers -- which
> > might generate slightly different code. I'll fix this issue and make
> > the build server selection more consistent.
> 
> Looking forward to seeing what shows up!

The new bisect catches commit 945fa9c631b04febe295a3a2a00c7e4a3cfb97db
("torture: Dump ftrace buffer when the RCU grace period stalls"). I
just reported it in another email.

Thanks,
Fengguang
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/