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

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!