Re: [RCU] kernel hangs in wait_rcu_gp during suspend path

2014-12-19 Thread Paul E. McKenney
On Sat, Dec 20, 2014 at 12:25:57AM +0530, Arun KS wrote: > Hi Paul, > > On Fri, Dec 19, 2014 at 1:35 AM, Paul E. McKenney > wrote: > > On Thu, Dec 18, 2014 at 09:52:28PM +0530, Arun KS wrote: > >> Hi Paul, > >> > >> On Thu, Dec 18, 2014 at 12:54 AM, Paul E. McKenney > >> wrote: > >> > On Tue, De

Re: [RCU] kernel hangs in wait_rcu_gp during suspend path

2014-12-19 Thread Arun KS
Hi Paul, On Fri, Dec 19, 2014 at 1:35 AM, Paul E. McKenney wrote: > On Thu, Dec 18, 2014 at 09:52:28PM +0530, Arun KS wrote: >> Hi Paul, >> >> On Thu, Dec 18, 2014 at 12:54 AM, Paul E. McKenney >> wrote: >> > On Tue, Dec 16, 2014 at 11:00:20PM +0530, Arun KS wrote: >> >> Hello, >> >> >> >> Addin

Re: [RCU] kernel hangs in wait_rcu_gp during suspend path

2014-12-18 Thread Paul E. McKenney
On Thu, Dec 18, 2014 at 09:52:28PM +0530, Arun KS wrote: > Hi Paul, > > On Thu, Dec 18, 2014 at 12:54 AM, Paul E. McKenney > wrote: > > On Tue, Dec 16, 2014 at 11:00:20PM +0530, Arun KS wrote: > >> Hello, > >> > >> Adding some more info. > >> > >> Below is the rcu_data data structure correspondin

Re: [RCU] kernel hangs in wait_rcu_gp during suspend path

2014-12-18 Thread Arun KS
Hi Paul, On Thu, Dec 18, 2014 at 12:54 AM, Paul E. McKenney wrote: > On Tue, Dec 16, 2014 at 11:00:20PM +0530, Arun KS wrote: >> Hello, >> >> Adding some more info. >> >> Below is the rcu_data data structure corresponding to cpu4. > > This shows that RCU is idle. What was the state of the system

Re: [RCU] kernel hangs in wait_rcu_gp during suspend path

2014-12-17 Thread Paul E. McKenney
On Tue, Dec 16, 2014 at 11:59:07AM +0530, Arun KS wrote: > Hello, > > I dig little deeper to understand the situation. > All other cpus are in idle thread already. > As per my understanding, for the grace period to end, at-least one of > the following should happen on all online cpus, > > 1. a co

Re: [RCU] kernel hangs in wait_rcu_gp during suspend path

2014-12-17 Thread Paul E. McKenney
On Tue, Dec 16, 2014 at 11:00:20PM +0530, Arun KS wrote: > Hello, > > Adding some more info. > > Below is the rcu_data data structure corresponding to cpu4. This shows that RCU is idle. What was the state of the system at the time you collected this data?

Re: [RCU] kernel hangs in wait_rcu_gp during suspend path

2014-12-16 Thread Paul E. McKenney
On Mon, Dec 15, 2014 at 10:34:58PM +0530, Arun KS wrote: > Hi, > > Here is the backtrace of the process hanging in wait_rcu_gp, > > PID: 247TASK: e16e7380 CPU: 4 COMMAND: "kworker/u16:5" > #0 [] (__schedule) from [] > #1 [] (schedule_timeout) from [] > #2 [] (wait_for_common) from [] >

Re: [RCU] kernel hangs in wait_rcu_gp during suspend path

2014-12-16 Thread Arun KS
Hello, Adding some more info. Below is the rcu_data data structure corresponding to cpu4. struct rcu_data { completed = 5877, gpnum = 5877, passed_quiesce = true, qs_pending = false, beenonline = true, preemptible = true, mynode = 0xc117f340 , grpmask = 16, nxtlist = 0xedaaec00

Re: [RCU] kernel hangs in wait_rcu_gp during suspend path

2014-12-15 Thread Arun KS
Hello, I dig little deeper to understand the situation. All other cpus are in idle thread already. As per my understanding, for the grace period to end, at-least one of the following should happen on all online cpus, 1. a context switch. 2. user space switch. 3. switch to idle thread. In this si

[RCU] kernel hangs in wait_rcu_gp during suspend path

2014-12-15 Thread Arun KS
Hi, Here is the backtrace of the process hanging in wait_rcu_gp, PID: 247TASK: e16e7380 CPU: 4 COMMAND: "kworker/u16:5" #0 [] (__schedule) from [] #1 [] (schedule_timeout) from [] #2 [] (wait_for_common) from [] #3 [] (wait_rcu_gp) from [] #4 [] (atomic_notifier_chain_unregister) from