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

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Message-ID: <CAOJe8K2iVOy9=Ds09_ePct3xR6qCH0U4XoKW-qP_TNEMe8GAmQ@mail.gmail.com>
Date:	Tue, 19 Jan 2016 14:53:51 +0300
From:	Denis Kirjanov <kda@...ux-powerpc.org>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org,
	Michael Ellerman <mpe@...erman.id.au>
Subject: Re: [PATCH v3 2/2] powerpc: tracing: don't trace hcalls on offline CPUs

On 1/12/16, Michael Ellerman <mpe@...erman.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@...ux-powerpc.org>

Hi Steven,

please apply with Michael's acked-by tag.

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