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

2014-09-13 Thread 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

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

2014-09-13 Thread 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.

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

2014-09-04 Thread Paul E. McKenney
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

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

2014-09-04 Thread Fengguang Wu
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

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

2014-09-04 Thread Fengguang Wu
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

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

2014-09-04 Thread Paul E. McKenney
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

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

2014-09-02 Thread Paul E. McKenney
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,

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

2014-09-02 Thread Christoph Lameter
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

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

2014-09-02 Thread Paul E. McKenney
On Tue, Sep 02, 2014 at 11:00:12AM -0500, Christoph Lameter wrote: > On Tue, 2 Sep 2014, Paul E. McKenney wrote: > > > Before this commit, raw_cpu_add_return() didn't build. The commit > > didn't affect anything else. > > > > So I don't understand how anything could work before this commit and >

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

2014-09-02 Thread Christoph Lameter
On Tue, 2 Sep 2014, Paul E. McKenney wrote: > Before this commit, raw_cpu_add_return() didn't build. The commit > didn't affect anything else. > > So I don't understand how anything could work before this commit and > be broken after it. Enlightenment? Where is that raw_cpu_add_return

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

2014-09-02 Thread Christoph Lameter
On Tue, 2 Sep 2014, Paul E. McKenney wrote: Before this commit, raw_cpu_add_return() didn't build. The commit didn't affect anything else. So I don't understand how anything could work before this commit and be broken after it. Enlightenment? Where is that raw_cpu_add_return statement?

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

2014-09-02 Thread Paul E. McKenney
On Tue, Sep 02, 2014 at 11:00:12AM -0500, Christoph Lameter wrote: On Tue, 2 Sep 2014, Paul E. McKenney wrote: Before this commit, raw_cpu_add_return() didn't build. The commit didn't affect anything else. So I don't understand how anything could work before this commit and be broken

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

2014-09-02 Thread Christoph Lameter
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

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

2014-09-02 Thread Paul E. McKenney
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