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Re: [PATCH v3 2/2] powerpc: tracing: don't trace hcalls on offline CPUs

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  Re: [PATCH v3 2/2] powerpc: tracing: don't trace hcalls on offline CPUs Denis Kirjanov <kda@linux-powerpc.org> - 2016-02-05 12:30 +0100
    Re: [PATCH v3 2/2] powerpc: tracing: don't trace hcalls on offline  CPUs Steven Rostedt <rostedt@goodmis.org> - 2016-02-05 15:40 +0100
      Re: [PATCH v3 2/2] powerpc: tracing: don't trace hcalls on offline CPUs Denis Kirjanov <kda@linux-powerpc.org> - 2016-02-05 15:50 +0100
      Re: [PATCH v3 2/2] powerpc: tracing: don't trace hcalls on offline  CPUs Michael Ellerman <mpe@ellerman.id.au> - 2016-02-09 10:30 +0100

#1327614 — Re: [PATCH v3 2/2] powerpc: tracing: don't trace hcalls on offline CPUs

On 1/19/16, Denis Kirjanov <kda@linux-powerpc.org> wrote:
> On 1/12/16, Michael Ellerman <mpe@ellerman.id.au> wrote:
>> On Mon, 2015-12-14 at 23:18 +0300, Denis Kirjanov wrote:
>>
>>> ./drmgr -c cpu -a -r gives the following warning:
>>>
>>> [ 2327.035563]
>>> RCU used illegally from offline CPU!
>>> rcu_scheduler_active = 1, debug_locks = 1
>>> [ 2327.035564] no locks held by swapper/12/0.
>>> [ 2327.035565]
>>> stack backtrace:
>>> [ 2327.035567] CPU: 12 PID: 0 Comm: swapper/12 Tainted: G S
>>> 4.3.0-rc3-00060-g353169a #5
>>> [ 2327.035568] Call Trace:
>>> [ 2327.035573] [c0000001d62578e0] [c0000000008977fc]
>>> .dump_stack+0x98/0xd4
>>> (unreliable)
>>> [ 2327.035577] [c0000001d6257960] [c000000000109bd8]
>>> .lockdep_rcu_suspicious+0x108/0x170
>>> [ 2327.035580] [c0000001d62579f0] [c00000000006a1d0]
>>> .__trace_hcall_exit+0x2b0/0x2c0
>>> [ 2327.035584] [c0000001d6257ab0] [c00000000006a2e8]
>>> plpar_hcall_norets_trace+0x70/0x8c
>>> [ 2327.035588] [c0000001d6257b20] [c000000000067a14]
>>> .icp_hv_set_cpu_priority+0x54/0xc0
>>> [ 2327.035592] [c0000001d6257ba0] [c000000000066c5c]
>>> .xics_teardown_cpu+0x5c/0xa0
>>> [ 2327.035595] [c0000001d6257c20] [c0000000000747ac]
>>> .pseries_mach_cpu_die+0x6c/0x320
>>> [ 2327.035598] [c0000001d6257cd0] [c0000000000439cc] .cpu_die+0x3c/0x60
>>> [ 2327.035602] [c0000001d6257d40] [c0000000000183d8]
>>> .arch_cpu_idle_dead+0x28/0x40
>>> [ 2327.035606] [c0000001d6257db0] [c0000000000ff1dc]
>>> .cpu_startup_entry+0x4fc/0x560
>>> [ 2327.035610] [c0000001d6257ed0] [c000000000043728]
>>> .start_secondary+0x328/0x360
>>> [ 2327.035614] [c0000001d6257f90] [c000000000008a6c]
>>> start_secondary_prolog+0x10/0x14
>>> [ 2327.035620] cpu 12 (hwid 12) Ready to die...
>>> [ 2327.144463] cpu 13 (hwid 13) Ready to die...
>>> [ 2327.294180] cpu 14 (hwid 14) Ready to die...
>>> [ 2327.403599] cpu 15 (hwid 15) Ready to die...
>>>
>>> Make the hypervisor tracepoints conditional
>>> by using TRACE_EVENT_FN_COND
>>>
>>> Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
>
> Hi Steven,
>
> please apply with Michael's acked-by tag.

ping

>
> Thanks!
>>
>> Acked-by: Michael Ellerman <mpe@ellerman.id.au>
>>
>> cheers
>>
>>
>

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#1327799 — Re: [PATCH v3 2/2] powerpc: tracing: don't trace hcalls on offline CPUs

On Fri, 5 Feb 2016 14:20:17 +0300
Denis Kirjanov <kda@linux-powerpc.org> wrote:

> >>> Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>  
> >
> > Hi Steven,
> >
> > please apply with Michael's acked-by tag.  
> 
> ping
> 

Actually, can you take this through the ppc tree? The
TRACE_EVENT_FN_COND is already in mainline.

You can add my:

Acked-by: Steven Rostedt <rostedt@goodmis.org>

-- Steve

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#1327813

On 2/5/16, Steven Rostedt <rostedt@goodmis.org> wrote:
> On Fri, 5 Feb 2016 14:20:17 +0300
> Denis Kirjanov <kda@linux-powerpc.org> wrote:
>
>> >>> Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
>> >
>> > Hi Steven,
>> >
>> > please apply with Michael's acked-by tag.
>>
>> ping
>>
>
> Actually, can you take this through the ppc tree? The
> TRACE_EVENT_FN_COND is already in mainline.
>
> You can add my:
>
> Acked-by: Steven Rostedt <rostedt@goodmis.org>

Hey Michael,

Please apply the patch.

Thanks!

>
> -- Steve
>

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#1329994 — Re: [PATCH v3 2/2] powerpc: tracing: don't trace hcalls on offline CPUs

On Fri, 2016-02-05 at 09:36 -0500, Steven Rostedt wrote:
> On Fri, 5 Feb 2016 14:20:17 +0300
> Denis Kirjanov <kda@linux-powerpc.org> wrote:
> > > > > Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
> > >
> > > Hi Steven,
> > >
> > > please apply with Michael's acked-by tag.
> >
> > ping
>
> Actually, can you take this through the ppc tree? The
> TRACE_EVENT_FN_COND is already in mainline.
>
> You can add my:
>
> Acked-by: Steven Rostedt <rostedt@goodmis.org>

Thanks, will do.

I tidied up the change log a bit:

    powerpc/pseries: Don't trace hcalls on offline CPUs

    If a cpu is hotplugged while the hcall trace points are active, it's
    possible to hit a warning from RCU due to the trace points calling into
    RCU from an offline cpu, eg:

      RCU used illegally from offline CPU!
      rcu_scheduler_active = 1, debug_locks = 1

    Make the hypervisor tracepoints conditional by using
    TRACE_EVENT_FN_COND.

    Acked-by: Steven Rostedt <rostedt@goodmis.org>
    Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
    Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>


cheers

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