Re: [patch-rt] sched,fair: Fix CFS bandwidth control lockdep DEADLOCK report

2018-05-15 Thread Sebastian Andrzej Siewior 
On 2018-05-04 10:48:02 [-0400], Steven Rostedt wrote:
> On Fri, 04 May 2018 08:14:38 +0200
> Mike Galbraith  wrote:
> 
…
> Looks good to me.
> 
> Acked-by: Steven Rostedt (VMware) 

trimmed commit message, tagged stable, applied.

> -- Steve

Sebastian

Re: [patch-rt] sched,fair: Fix CFS bandwidth control lockdep DEADLOCK report

2018-05-04 Thread Steven Rostedt 
On Fri, 04 May 2018 08:14:38 +0200
Mike Galbraith  wrote:

> CFS bandwidth control yields the inversion gripe below, moving
> handling quells it.
> 
> 
> WARNING: possible irq lock inversion dependency detected
> 4.16.7-rt1-rt #2 Tainted: GE   
> 
> sirq-hrtimer/0/15 just changed the state of lock:
>  (&cfs_b->lock){+...}, at: [<9adb5cf7>] 
> sched_cfs_period_timer+0x28/0x140
> but this lock was taken by another, HARDIRQ-safe lock in the past:
>  (&rq->lock){-...}
> and interrupts could create inverse lock ordering between them.
> other info that might help us debug this:
>  Possible interrupt unsafe locking scenario: 
>CPU0CPU1
>
>   lock(&cfs_b->lock);
>local_irq_disable();
>lock(&rq->lock);
>lock(&cfs_b->lock);
>   
> lock(&rq->lock);
> *** DEADLOCK *** 


> Signed-off-by: Mike Galbraith 
> ---
>  kernel/sched/fair.c |4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -5007,9 +5007,9 @@ void init_cfs_bandwidth(struct cfs_bandw
>   cfs_b->period = ns_to_ktime(default_cfs_period());
>  
>   INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq);
> - hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, 
> HRTIMER_MODE_ABS_PINNED);
> + hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, 
> HRTIMER_MODE_ABS_PINNED_HARD);
>   cfs_b->period_timer.function = sched_cfs_period_timer;
> - hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> + hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, 
> HRTIMER_MODE_REL_HARD);

Looks good to me.

Acked-by: Steven Rostedt (VMware) 

-- Steve

>   cfs_b->slack_timer.function = sched_cfs_slack_timer;
>  }
>

[patch-rt] sched,fair: Fix CFS bandwidth control lockdep DEADLOCK report

2018-05-03 Thread Mike Galbraith 
CFS bandwidth control yields the inversion gripe below, moving
handling quells it.


WARNING: possible irq lock inversion dependency detected
4.16.7-rt1-rt #2 Tainted: GE   

sirq-hrtimer/0/15 just changed the state of lock:
 (&cfs_b->lock){+...}, at: [<9adb5cf7>] 
sched_cfs_period_timer+0x28/0x140
but this lock was taken by another, HARDIRQ-safe lock in the past:
 (&rq->lock){-...}
and interrupts could create inverse lock ordering between them.
other info that might help us debug this:
 Possible interrupt unsafe locking scenario: 
   CPU0CPU1
   
  lock(&cfs_b->lock);
   local_irq_disable();
   lock(&rq->lock);
   lock(&cfs_b->lock);
  
lock(&rq->lock);
*** DEADLOCK *** 
1 lock held by sirq-hrtimer/0/15:
 #0:  (&per_cpu(local_softirq_locks[i], __cpu).lock){+.+.}, at: 
[<61d5600a>] do_current_softirqs+0x170/0x660
the shortest dependencies between 2nd lock and 1st lock:
 -> (&rq->lock){-...} ops: 67919540 {
IN-HARDIRQ-W at:
  _raw_spin_lock+0x38/0x50
  scheduler_tick+0x4c/0x110
  update_process_times+0x21/0x50
  tick_periodic+0x2b/0x100
  tick_handle_periodic+0x1f/0x60
  timer_interrupt+0x14/0x20
  __handle_irq_event_percpu+0x5f/0x3f0
  handle_irq_event_percpu+0x37/0x70
  handle_irq_event+0x37/0x60
  handle_edge_irq+0xbe/0x1e0
  handle_irq+0x1f/0x30
  do_IRQ+0x65/0x130
  ret_from_intr+0x0/0x22
  timer_irq_works+0x60/0x10e
  setup_IO_APIC+0x620/0x7e3
  x86_late_time_init+0x17/0x1c
  start_kernel+0x410/0x4b3
  secondary_startup_64+0xa5/0xb0
INITIAL USE at:
 _raw_spin_lock_irqsave+0x4f/0x70
 rq_attach_root+0x18/0xe0
 sched_init+0x2ea/0x413
 start_kernel+0x282/0x4b3
 secondary_startup_64+0xa5/0xb0
  }
  ... key  at: [<0ab3ac7a>] __key.69727+0x0/0x8
  ... acquired at:
   lock_acquire+0xbd/0x250
   _raw_spin_lock+0x38/0x50
   rq_online_fair+0x9a/0x190
   set_rq_online+0x4c/0x60
   rq_attach_root+0xac/0xe0
   sched_init+0x2ea/0x413
   start_kernel+0x282/0x4b3
   secondary_startup_64+0xa5/0xb0 
-> (&cfs_b->lock){+...} ops: 56 {
   HARDIRQ-ON-W at:
_raw_spin_lock+0x38/0x50
sched_cfs_period_timer+0x28/0x140
__hrtimer_run_queues+0x10e/0x5f0
hrtimer_run_softirq+0x83/0xc0
do_current_softirqs+0x292/0x660
run_ksoftirqd+0x27/0x70
smpboot_thread_fn+0x27f/0x330
kthread+0x103/0x140
ret_from_fork+0x3a/0x50
   INITIAL USE at:
   _raw_spin_lock+0x38/0x50
   rq_online_fair+0x9a/0x190
   set_rq_online+0x4c/0x60
   rq_attach_root+0xac/0xe0
   sched_init+0x2ea/0x413
   start_kernel+0x282/0x4b3
   secondary_startup_64+0xa5/0xb0
 }
 ... key  at: [] __key.47691+0x0/0x8
 ... acquired at:
   __lock_acquire+0x1e6/0x770
   lock_acquire+0xbd/0x250
   _raw_spin_lock+0x38/0x50
   sched_cfs_period_timer+0x28/0x140
   __hrtimer_run_queues+0x10e/0x5f0
   hrtimer_run_softirq+0x83/0xc0
   do_current_softirqs+0x292/0x660
   run_ksoftirqd+0x27/0x70
   smpboot_thread_fn+0x27f/0x330
   kthread+0x103/0x140
   ret_from_fork+0x3a/0x50 
stack backtrace:
CPU: 0 PID: 15 Comm: sirq-hrtimer/0 Tainted: GE4.16.7-rt1-rt #2
Hardware name: MEDION MS-7848/MS-7848, BIOS M7848W08.20C 09/23/2013
Call Trace:
 dump_stack+0x78/0xab
 print_irq_inversion_bug.part.38+0x19f/0x1aa
 check_usage_backwards+0x11b/0x120
 ? check_usage_forwards+0x130/0x130
 mark_lock+0x17c/0x280
 __lock_acquire+0x1e6/0x770
 lock_acquire+0xbd/0x250
 ? sched_cfs_period_timer+0x28/0x140
 _raw_spin_lock+0x38/0x50
 ? sched_cfs_period_timer+0x28/0x140
 sched_cfs_period_timer+0x28/0x140
 ? sched_cfs_slack_timer+0xc0/0xc0
 __hrtimer_run_queues+0x10e/0x5f0
 hrtimer_run_softirq+0x83/0xc0
 do_current_softirqs+0x292/0x660
 run_ksoftirqd+0x27/0x70
 smpboot_thread_fn+0x27f/0x330
 kthread+0x103/0x140
 ? smpboot_register_percpu_thread_cpumask+0x100/0x100
 ? kthread_delayed_work_timer_fn+0x90/0x90
 ret_from_fork+0x3a/0x50

Signed-off-by: Mike Galbraith 
---
 kernel/sched/fair.c |4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5007,9 +5007,9 @@ void init_cfs_bandwidth(struct