Re: RCU idle CPU detection is broken in linux-next

2012-09-26 Thread Paul E. McKenney
On Wed, Sep 26, 2012 at 05:46:13PM +0200, Frederic Weisbecker wrote: > On Tue, Sep 25, 2012 at 11:36:54AM -0700, Paul E. McKenney wrote: > > On Tue, Sep 25, 2012 at 08:28:23PM +0200, Sasha Levin wrote: > > > On 09/25/2012 02:06 PM, Frederic Weisbecker wrote: > > > > Sasha, sorry to burden you with

Re: RCU idle CPU detection is broken in linux-next

2012-09-26 Thread Paul E. McKenney
On Wed, Sep 26, 2012 at 04:56:55PM +0200, Frederic Weisbecker wrote: > 2012/9/25 Paul E. McKenney : > > On Tue, Sep 25, 2012 at 01:59:26PM +0200, Frederic Weisbecker wrote: > >> Given that we have: > >> > >> rcu_irq_enter() > >> rcu_user_exit() > >> rcu_user_enter() > >> rcu_irq_exit()

Re: RCU idle CPU detection is broken in linux-next

2012-09-26 Thread Frederic Weisbecker
On Tue, Sep 25, 2012 at 11:36:54AM -0700, Paul E. McKenney wrote: > On Tue, Sep 25, 2012 at 08:28:23PM +0200, Sasha Levin wrote: > > On 09/25/2012 02:06 PM, Frederic Weisbecker wrote: > > > Sasha, sorry to burden you with more testing request. > > > Could you please try out this new branch? It incl

Re: RCU idle CPU detection is broken in linux-next

2012-09-26 Thread Frederic Weisbecker
2012/9/25 Sasha Levin : > On 09/25/2012 02:06 PM, Frederic Weisbecker wrote: >> Sasha, sorry to burden you with more testing request. >> Could you please try out this new branch? It includes some fixes after Wu >> Fenguang and >> Dan Carpenter reports (not related to your warnings though) and a pa

Re: RCU idle CPU detection is broken in linux-next

2012-09-26 Thread Frederic Weisbecker
2012/9/25 Paul E. McKenney : > On Tue, Sep 25, 2012 at 01:59:26PM +0200, Frederic Weisbecker wrote: >> Given that we have: >> >> rcu_irq_enter() >> rcu_user_exit() >> rcu_user_enter() >> rcu_irq_exit() > > Indeed, the code to deal with irq misnestings won't like that at all. > And we ar

Re: RCU idle CPU detection is broken in linux-next

2012-09-25 Thread Paul E. McKenney
On Tue, Sep 25, 2012 at 08:28:23PM +0200, Sasha Levin wrote: > On 09/25/2012 02:06 PM, Frederic Weisbecker wrote: > > Sasha, sorry to burden you with more testing request. > > Could you please try out this new branch? It includes some fixes after Wu > > Fenguang and > > Dan Carpenter reports (not

Re: RCU idle CPU detection is broken in linux-next

2012-09-25 Thread Sasha Levin
On 09/25/2012 02:06 PM, Frederic Weisbecker wrote: > Sasha, sorry to burden you with more testing request. > Could you please try out this new branch? It includes some fixes after Wu > Fenguang and > Dan Carpenter reports (not related to your warnings though) and a patch on > the top > of the pil

Re: RCU idle CPU detection is broken in linux-next

2012-09-25 Thread Paul E. McKenney
On Tue, Sep 25, 2012 at 01:59:26PM +0200, Frederic Weisbecker wrote: > On Mon, Sep 24, 2012 at 09:04:20PM -0700, Paul E. McKenney wrote: > > On Tue, Sep 25, 2012 at 01:41:18AM +0200, Frederic Weisbecker wrote: > > > > > > > > [ 168.703017] [ cut here ] > > > > [ 168.708117

Re: RCU idle CPU detection is broken in linux-next

2012-09-25 Thread Frederic Weisbecker
On Tue, Sep 25, 2012 at 01:10:27AM +0200, Sasha Levin wrote: > On 09/25/2012 01:06 AM, Frederic Weisbecker wrote: > > 2012/9/25 Sasha Levin : > >> On 09/25/2012 12:47 AM, Sasha Levin wrote: > >>> - While I no longer see the warnings I've originally noticed, if I run > >>> with Paul's last debug p

Re: RCU idle CPU detection is broken in linux-next

2012-09-25 Thread Frederic Weisbecker
On Mon, Sep 24, 2012 at 09:04:20PM -0700, Paul E. McKenney wrote: > On Tue, Sep 25, 2012 at 01:41:18AM +0200, Frederic Weisbecker wrote: > > > > > > [ 168.703017] [ cut here ] > > > [ 168.708117] WARNING: at kernel/rcutree.c:502 > > > rcu_eqs_exit_common+0x4a/0x3a0() > >

Re: RCU idle CPU detection is broken in linux-next

2012-09-24 Thread Paul E. McKenney
On Tue, Sep 25, 2012 at 01:41:18AM +0200, Frederic Weisbecker wrote: > 2012/9/25 Frederic Weisbecker : > > 2012/9/25 Sasha Levin : > >> On 09/25/2012 01:06 AM, Frederic Weisbecker wrote: > >>> 2012/9/25 Sasha Levin : > On 09/25/2012 12:47 AM, Sasha Levin wrote: > > - While I no longer see

Re: RCU idle CPU detection is broken in linux-next

2012-09-24 Thread Frederic Weisbecker
2012/9/25 Frederic Weisbecker : > 2012/9/25 Sasha Levin : >> On 09/25/2012 01:06 AM, Frederic Weisbecker wrote: >>> 2012/9/25 Sasha Levin : On 09/25/2012 12:47 AM, Sasha Levin wrote: > - While I no longer see the warnings I've originally noticed, if I run > with Paul's last debug pat

Re: RCU idle CPU detection is broken in linux-next

2012-09-24 Thread Frederic Weisbecker
2012/9/25 Sasha Levin : > On 09/25/2012 01:06 AM, Frederic Weisbecker wrote: >> 2012/9/25 Sasha Levin : >>> On 09/25/2012 12:47 AM, Sasha Levin wrote: - While I no longer see the warnings I've originally noticed, if I run with Paul's last debug patch I see the following warning: >>> >>>

Re: RCU idle CPU detection is broken in linux-next

2012-09-24 Thread Frederic Weisbecker
2012/9/25 Sasha Levin : > On 09/25/2012 12:47 AM, Sasha Levin wrote: >> - While I no longer see the warnings I've originally noticed, if I run with >> Paul's last debug patch I see the following warning: > > Correction: Original warnings are still there, they just got buried in the > huge spew t

Re: RCU idle CPU detection is broken in linux-next

2012-09-24 Thread Sasha Levin
On 09/25/2012 12:47 AM, Sasha Levin wrote: > - While I no longer see the warnings I've originally noticed, if I run with > Paul's last debug patch I see the following warning: Correction: Original warnings are still there, they just got buried in the huge spew that was caused by additional debu

Re: RCU idle CPU detection is broken in linux-next

2012-09-24 Thread Sasha Levin
Hi Frederic, On 09/24/2012 11:29 PM, Frederic Weisbecker wrote: > Sasha, > > Can you please test the following branch: > > git://github.com/fweisbec/linux-dynticks.git rcu/idle-for-v3.7-take3 > > with CONFIG_RCU_USER_QS and CONFIG_RCU_USER_QS_FORCE enabled. > > I hope this fixes the warning.

Re: RCU idle CPU detection is broken in linux-next

2012-09-24 Thread Frederic Weisbecker
2012/9/23 Sasha Levin : > On 09/23/2012 02:21 AM, Paul E. McKenney wrote: >> On Sat, Sep 22, 2012 at 02:27:35PM -0700, Paul E. McKenney wrote: >>> On Sat, Sep 22, 2012 at 07:50:29PM +0200, Sasha Levin wrote: On 09/22/2012 05:56 PM, Paul E. McKenney wrote: > And now the prime suspect is the

Re: RCU idle CPU detection is broken in linux-next

2012-09-22 Thread Sasha Levin
On 09/23/2012 02:21 AM, Paul E. McKenney wrote: > On Sat, Sep 22, 2012 at 02:27:35PM -0700, Paul E. McKenney wrote: >> On Sat, Sep 22, 2012 at 07:50:29PM +0200, Sasha Levin wrote: >>> On 09/22/2012 05:56 PM, Paul E. McKenney wrote: And now the prime suspect is the new CONFIG_RCU_USER_QS=y. Do

Re: RCU idle CPU detection is broken in linux-next

2012-09-22 Thread Paul E. McKenney
On Sat, Sep 22, 2012 at 02:27:35PM -0700, Paul E. McKenney wrote: > On Sat, Sep 22, 2012 at 07:50:29PM +0200, Sasha Levin wrote: > > On 09/22/2012 05:56 PM, Paul E. McKenney wrote: > > > And now the prime suspect is the new CONFIG_RCU_USER_QS=y. Do these > > > warnings ever show up with CONFIG_RCU

Re: RCU idle CPU detection is broken in linux-next

2012-09-22 Thread Paul E. McKenney
On Sat, Sep 22, 2012 at 07:50:29PM +0200, Sasha Levin wrote: > On 09/22/2012 05:56 PM, Paul E. McKenney wrote: > > And now the prime suspect is the new CONFIG_RCU_USER_QS=y. Do these > > warnings ever show up with CONFIG_RCU_USER_QS=n? > > It seems that disabling that does make the warnings go aw

Re: RCU idle CPU detection is broken in linux-next

2012-09-22 Thread Sasha Levin
On 09/22/2012 05:56 PM, Paul E. McKenney wrote: > And now the prime suspect is the new CONFIG_RCU_USER_QS=y. Do these > warnings ever show up with CONFIG_RCU_USER_QS=n? It seems that disabling that does make the warnings go away. I'll keep the tests running in case it just reduces the chances or

Re: RCU idle CPU detection is broken in linux-next

2012-09-22 Thread Paul E. McKenney
On Sat, Sep 22, 2012 at 08:09:13AM -0700, Paul E. McKenney wrote: > On Sat, Sep 22, 2012 at 10:26:09AM +0200, Sasha Levin wrote: > > On 09/21/2012 05:18 PM, Sasha Levin wrote: > > > On 09/21/2012 05:12 PM, Paul E. McKenney wrote: > > >> On Fri, Sep 21, 2012 at 03:26:27PM +0200, Sasha Levin wrote: >

Re: RCU idle CPU detection is broken in linux-next

2012-09-22 Thread Paul E. McKenney
On Sat, Sep 22, 2012 at 10:26:09AM +0200, Sasha Levin wrote: > On 09/21/2012 05:18 PM, Sasha Levin wrote: > > On 09/21/2012 05:12 PM, Paul E. McKenney wrote: > >> On Fri, Sep 21, 2012 at 03:26:27PM +0200, Sasha Levin wrote: > >>> On 09/21/2012 02:13 PM, Paul E. McKenney wrote: > > This might be

Re: RCU idle CPU detection is broken in linux-next

2012-09-22 Thread Sasha Levin
On 09/21/2012 05:18 PM, Sasha Levin wrote: > On 09/21/2012 05:12 PM, Paul E. McKenney wrote: >> On Fri, Sep 21, 2012 at 03:26:27PM +0200, Sasha Levin wrote: >>> On 09/21/2012 02:13 PM, Paul E. McKenney wrote: > This might be unrelated, but I got the following dump as well when trinity >> de

Re: RCU idle CPU detection is broken in linux-next

2012-09-21 Thread Sasha Levin
On 09/21/2012 05:12 PM, Paul E. McKenney wrote: > On Fri, Sep 21, 2012 at 03:26:27PM +0200, Sasha Levin wrote: >> On 09/21/2012 02:13 PM, Paul E. McKenney wrote: This might be unrelated, but I got the following dump as well when trinity > decided it's time to reboot my guest: >>> OK, sound

Re: RCU idle CPU detection is broken in linux-next

2012-09-21 Thread Paul E. McKenney
On Fri, Sep 21, 2012 at 03:26:27PM +0200, Sasha Levin wrote: > On 09/21/2012 02:13 PM, Paul E. McKenney wrote: > >> This might be unrelated, but I got the following dump as well when trinity > >> > decided it's time to reboot my guest: > > OK, sounds like we should hold off until you reproduce, the

Re: RCU idle CPU detection is broken in linux-next

2012-09-21 Thread Sasha Levin
On 09/21/2012 02:13 PM, Paul E. McKenney wrote: >> This might be unrelated, but I got the following dump as well when trinity >> > decided it's time to reboot my guest: > OK, sounds like we should hold off until you reproduce, then. I'm not sure what you mean. There are basically two issues I'm s

Re: RCU idle CPU detection is broken in linux-next

2012-09-21 Thread Paul E. McKenney
On Fri, Sep 21, 2012 at 11:30:33AM +0200, Sasha Levin wrote: > On 09/20/2012 05:23 PM, Paul E. McKenney wrote: > > On Thu, Sep 20, 2012 at 09:44:57AM +0200, Sasha Levin wrote: > >> On 09/20/2012 09:33 AM, Michael Wang wrote: > >>> On 09/20/2012 01:06 AM, Paul E. McKenney wrote: > On Wed, Sep 1

Re: RCU idle CPU detection is broken in linux-next

2012-09-21 Thread Sasha Levin
On 09/20/2012 05:23 PM, Paul E. McKenney wrote: > On Thu, Sep 20, 2012 at 09:44:57AM +0200, Sasha Levin wrote: >> On 09/20/2012 09:33 AM, Michael Wang wrote: >>> On 09/20/2012 01:06 AM, Paul E. McKenney wrote: On Wed, Sep 19, 2012 at 06:35:36PM +0200, Sasha Levin wrote: > On 09/19/2012 05:

Re: RCU idle CPU detection is broken in linux-next

2012-09-20 Thread Paul E. McKenney
On Thu, Sep 20, 2012 at 09:44:57AM +0200, Sasha Levin wrote: > On 09/20/2012 09:33 AM, Michael Wang wrote: > > On 09/20/2012 01:06 AM, Paul E. McKenney wrote: > >> On Wed, Sep 19, 2012 at 06:35:36PM +0200, Sasha Levin wrote: > >>> On 09/19/2012 05:39 PM, Paul E. McKenney wrote: > On Wed, Sep 1

Re: RCU idle CPU detection is broken in linux-next

2012-09-20 Thread Michael Wang
On 09/20/2012 03:44 PM, Sasha Levin wrote: > On 09/20/2012 09:33 AM, Michael Wang wrote: >> On 09/20/2012 01:06 AM, Paul E. McKenney wrote: >>> On Wed, Sep 19, 2012 at 06:35:36PM +0200, Sasha Levin wrote: On 09/19/2012 05:39 PM, Paul E. McKenney wrote: > On Wed, Sep 12, 2012 at 07:56:48PM

Re: RCU idle CPU detection is broken in linux-next

2012-09-20 Thread Sasha Levin
On 09/20/2012 09:33 AM, Michael Wang wrote: > On 09/20/2012 01:06 AM, Paul E. McKenney wrote: >> On Wed, Sep 19, 2012 at 06:35:36PM +0200, Sasha Levin wrote: >>> On 09/19/2012 05:39 PM, Paul E. McKenney wrote: On Wed, Sep 12, 2012 at 07:56:48PM +0200, Sasha Levin wrote: >> Hi Paul, >>

Re: RCU idle CPU detection is broken in linux-next

2012-09-20 Thread Michael Wang
On 09/20/2012 01:06 AM, Paul E. McKenney wrote: > On Wed, Sep 19, 2012 at 06:35:36PM +0200, Sasha Levin wrote: >> On 09/19/2012 05:39 PM, Paul E. McKenney wrote: >>> On Wed, Sep 12, 2012 at 07:56:48PM +0200, Sasha Levin wrote: > Hi Paul, > > While fuzzing using trinity inside a KVM tool

Re: RCU idle CPU detection is broken in linux-next

2012-09-19 Thread Sasha Levin
On 09/19/2012 07:06 PM, Paul E. McKenney wrote: > On Wed, Sep 19, 2012 at 06:35:36PM +0200, Sasha Levin wrote: >> On 09/19/2012 05:39 PM, Paul E. McKenney wrote: >>> On Wed, Sep 12, 2012 at 07:56:48PM +0200, Sasha Levin wrote: > Hi Paul, > > While fuzzing using trinity inside a KVM tool

Re: RCU idle CPU detection is broken in linux-next

2012-09-19 Thread Paul E. McKenney
On Wed, Sep 19, 2012 at 06:35:36PM +0200, Sasha Levin wrote: > On 09/19/2012 05:39 PM, Paul E. McKenney wrote: > > On Wed, Sep 12, 2012 at 07:56:48PM +0200, Sasha Levin wrote: > >> > Hi Paul, > >> > > >> > While fuzzing using trinity inside a KVM tools guest, I've managed to > >> > trigger > >> >

Re: RCU idle CPU detection is broken in linux-next

2012-09-19 Thread Sasha Levin
On 09/19/2012 05:39 PM, Paul E. McKenney wrote: > On Wed, Sep 12, 2012 at 07:56:48PM +0200, Sasha Levin wrote: >> > Hi Paul, >> > >> > While fuzzing using trinity inside a KVM tools guest, I've managed to >> > trigger >> > "RCU used illegally from idle CPU!" warnings several times. >> > >> > The

Re: RCU idle CPU detection is broken in linux-next

2012-09-19 Thread Paul E. McKenney
On Wed, Sep 12, 2012 at 07:56:48PM +0200, Sasha Levin wrote: > Hi Paul, > > While fuzzing using trinity inside a KVM tools guest, I've managed to trigger > "RCU used illegally from idle CPU!" warnings several times. > > There are a bunch of traces which seem to pop exactly at the same time and >

RCU idle CPU detection is broken in linux-next

2012-09-12 Thread Sasha Levin
Hi Paul, While fuzzing using trinity inside a KVM tools guest, I've managed to trigger "RCU used illegally from idle CPU!" warnings several times. There are a bunch of traces which seem to pop exactly at the same time and from different places around the kernel. Here are several of them: (1): [