Re: [rcu] BUG: unable to handle kernel NULL pointer dereference at 000000da

2014-09-13 Thread Fengguang Wu
On Fri, Sep 12, 2014 at 05:38:37PM -0700, Paul E. McKenney wrote: > On Sat, Sep 13, 2014 at 08:20:05AM +0800, Fengguang Wu wrote: > > On Fri, Sep 12, 2014 at 12:26:59PM -0700, Paul E. McKenney wrote: > > > On Fri, Sep 12, 2014 at 02:19:57PM -0500, Christoph Lameter wrote: > > > > On Fri, 12 Sep 201

Re: [rcu] BUG: unable to handle kernel NULL pointer dereference at 000000da

2014-09-12 Thread Paul E. McKenney
On Sat, Sep 13, 2014 at 08:20:05AM +0800, Fengguang Wu wrote: > On Fri, Sep 12, 2014 at 12:26:59PM -0700, Paul E. McKenney wrote: > > On Fri, Sep 12, 2014 at 02:19:57PM -0500, Christoph Lameter wrote: > > > On Fri, 12 Sep 2014, Paul E. McKenney wrote: > > > > > > > So, I am not seeing this failure

Re: [rcu] BUG: unable to handle kernel NULL pointer dereference at 000000da

2014-09-12 Thread Fengguang Wu
On Fri, Sep 12, 2014 at 12:26:59PM -0700, Paul E. McKenney wrote: > On Fri, Sep 12, 2014 at 02:19:57PM -0500, Christoph Lameter wrote: > > On Fri, 12 Sep 2014, Paul E. McKenney wrote: > > > > > So, I am not seeing this failure in my testing, but my best guess is > > > that the problem is due to th

Re: [rcu] BUG: unable to handle kernel NULL pointer dereference at 000000da

2014-09-12 Thread Pranith Kumar
On Fri, Sep 12, 2014 at 3:02 PM, Paul E. McKenney wrote: > On Mon, Sep 01, 2014 at 04:44:04PM +0800, Fengguang Wu wrote: >> Greetings, >> >> 0day kernel testing robot got the below dmesg and the first bad commit is >> >> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master >> co

Re: [rcu] BUG: unable to handle kernel NULL pointer dereference at 000000da

2014-09-12 Thread Paul E. McKenney
On Fri, Sep 12, 2014 at 02:19:57PM -0500, Christoph Lameter wrote: > On Fri, 12 Sep 2014, Paul E. McKenney wrote: > > > So, I am not seeing this failure in my testing, but my best guess is > > that the problem is due to the fact that force_quiescent_state() is > > sometimes invoked with preemption

Re: [rcu] BUG: unable to handle kernel NULL pointer dereference at 000000da

2014-09-12 Thread Christoph Lameter
On Fri, 12 Sep 2014, Paul E. McKenney wrote: > So, I am not seeing this failure in my testing, but my best guess is > that the problem is due to the fact that force_quiescent_state() is > sometimes invoked with preemption enabled, which breaks __this_cpu_read() > though perhaps with very low proba

Re: [rcu] BUG: unable to handle kernel NULL pointer dereference at 000000da

2014-09-12 Thread Paul E. McKenney
On Mon, Sep 01, 2014 at 04:44:04PM +0800, Fengguang Wu wrote: > Greetings, > > 0day kernel testing robot got the below dmesg and the first bad commit is > > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master > commit d860d40327dde251d508a234fa00bd0d90fbb656 > Author: Shan