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    SubjectRe: [v4.14-rt][report] arm: run: stress-ng --class os --all 0 -t 5m
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    On 12/19/2017 02:27 AM, Sebastian Andrzej Siewior wrote:
    > On 2017-12-18 20:01:05 [-0600], Grygorii Strashko wrote:
    >> Hi All,
    > Hi,
    >
    >> Below results of running stress-ng --class os --all 0 -t 5m on TI am57xx-evm (SMP, 2 cpu)
    >> git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
    >> branch: linux-4.14.y-rt
    >> commit: d3d9904 v4.14.6-rt7
    >> - only config changes applied.
    >>
    >> one "WARNING: possible circular locking dependency detected"
    >> [ 85.943562] ======================================================
    >> [ 85.943564] WARNING: possible circular locking dependency detected
    >> [ 85.943568] 4.14.6-rt7-dirty #29 Not tainted
    >> [ 85.943570] ------------------------------------------------------
    >> [ 85.943573] stress-ng-cpu-o/764 is trying to acquire lock:
    >> [ 85.943576] (&p->pi_lock){-...}, at: [<c0169ce8>] try_to_wake_up+0x28/0x924
    >> [ 85.943594]
    >> [ 85.943594] but task is already holding lock:
    >> [ 85.943596] (hrtimer_bases.lock){-...}, at: [<c01c12ac>] hrtimer_interrupt+0x68/0x2b0
    >>
    >> one "WARNING: CPU: 0 PID: 3514 at kernel/rcu/tree_plugin.h:310 rcu_note_context_switch+0x3e8/0x988"
    >> ^ sorry, log not very readable
    >
    > This should cure it, does it?
    >
    > diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
    > index c2c344fda487..3971fa0c7194 100644
    > --- a/kernel/time/hrtimer.c
    > +++ b/kernel/time/hrtimer.c
    > @@ -1952,6 +1952,7 @@ int hrtimers_dead_cpu(unsigned int scpu)
    > BUG_ON(cpu_online(scpu));
    > tick_cancel_sched_timer(scpu);
    >
    > + local_bh_disable();
    > local_irq_disable();
    > old_base = &per_cpu(hrtimer_bases, scpu);
    > new_base = this_cpu_ptr(&hrtimer_bases);
    > @@ -1979,6 +1980,7 @@ int hrtimers_dead_cpu(unsigned int scpu)
    > /* Check, if we got expired work to do */
    > __hrtimer_peek_ahead_timers();
    > local_irq_enable();
    > + local_bh_enable();
    > return 0;
    > }
    >

    I've run test few times - can't see "WARNING: possible circular locking dependency detected"
    any more. Below warning happened once.

    [ 3091.593894] ------------[ cut here ]------------
    [ 3091.593909] WARNING: CPU: 0 PID: 1797 at kernel/rcu/tree_plugin.h:310 rcu_note_context_switch+0x554/0x950
    [ 3091.593912] Modules linked in:
    [ 3091.593923] CPU: 0 PID: 1797 Comm: stress-ng-clock Not tainted 4.14.6-rt7-dirty #37
    [ 3091.593926] Hardware name: Generic DRA74X (Flattened Device Tree)
    [ 3091.593941] [<c0110090>] (unwind_backtrace) from [<c010c710>] (show_stack+0x10/0x14)
    [ 3091.593952] [<c010c710>] (show_stack) from [<c08388b8>] (dump_stack+0xa0/0xd4)
    [ 3091.593964] [<c08388b8>] (dump_stack) from [<c013668c>] (__warn+0xd8/0x104)
    [ 3091.593975] [<c013668c>] (__warn) from [<c0136764>] (warn_slowpath_null+0x20/0x28)
    [ 3091.593984] [<c0136764>] (warn_slowpath_null) from [<c01b8efc>] (rcu_note_context_switch+0x554/0x950)
    [ 3091.593996] [<c01b8efc>] (rcu_note_context_switch) from [<c084e08c>] (__schedule+0xc4/0xa7c)
    [ 3091.594005] [<c084e08c>] (__schedule) from [<c084eaa4>] (schedule+0x60/0xf8)
    [ 3091.594016] [<c084eaa4>] (schedule) from [<c08505b4>] (rt_spin_lock_slowlock_locked+0xa8/0x304)
    [ 3091.594026] [<c08505b4>] (rt_spin_lock_slowlock_locked) from [<c0851060>] (__read_rt_lock+0xc0/0xf4)
    [ 3091.594036] [<c0851060>] (__read_rt_lock) from [<c01398cc>] (pin_current_cpu+0x3c/0x11c)
    [ 3091.594047] [<c01398cc>] (pin_current_cpu) from [<c0167ce0>] (migrate_disable+0x78/0x1e8)
    [ 3091.594057] [<c0167ce0>] (migrate_disable) from [<c085248c>] (rt_spin_lock+0x14/0x4c)
    [ 3091.594066] [<c085248c>] (rt_spin_lock) from [<c01cb150>] (__lock_timer+0xc0/0x220)
    [ 3091.594076] [<c01cb150>] (__lock_timer) from [<c01cc2b8>] (SyS_timer_gettime+0x14/0xb8)
    [ 3091.594087] [<c01cc2b8>] (SyS_timer_gettime) from [<c01079c8>] (__sys_trace_return+0x0/0x10)
    [ 3091.594091] ---[ end trace 0000000000000002 ]---


    --
    regards,
    -grygorii

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