From: Daniel Lezcano <daniel.lezcano@linaro.org>
To: Sebastian Parschauer <sebastian.riemer@profitbricks.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: linux-pm@vger.kernel.org
Subject: Re: cpuidle: Kernel panics with AMD Opteron 6300 entering C2 - clock related
Date: Thu, 18 Jun 2015 11:22:05 +0200 [thread overview]
Message-ID: <55828DBD.5000109@linaro.org> (raw)
In-Reply-To: <55814696.1050803@profitbricks.com>
On 06/17/2015 12:06 PM, Sebastian Parschauer wrote:
> Hi cpuidle maintainers,
>
> we notice kernel panics with CPUs from the AMD Opteron 6300 series and
> kernel 3.12 when entering C2. In that C-state the clock is shut down but
> the flag CPUIDLE_FLAG_TIMER_STOP isn't set. We use the TSC clock source
> for performance as our servers host KVM VMs. During the panics
> interrupts are enabled again and the timer interrupt corrupts the
> instruction pointer and/or the stack pointer.
>
> Would it help to set the flag CPUIDLE_FLAG_TIMER_STOP for C2?
> Or how to fix this?
Did you try the flag ? Does it fix it ?
> ==========
> Additional debug info:
>
> BUG: unable to handle kernel NULL pointer dereference at (null)
> IP: [< (null)>] (null)
> ...
> Call trace:
> [<ffffffff815af9b5>] cpuidle_idle_call+0xc5/0x150
> [<ffffffff8100b529>] arch_cpu_idle+0x9/0x20
> [<ffffffff81092e6f>] cpu_startup_entry+0xaf/0x240
> [<ffffffff8102df4b>] start_secondary+0x1db/0x240
>
> The CPUs provide three C-states:
> 0: POLL
> 1: C1
> 2: C2
>
> C2 information from the crash dump:
>
>> {
>> name = "C2\000\000\000\000\000\000\000\000\000\000\000\000\000",
>> desc = "ACPI IOPORT 0x815\000\000\000\000\000\000\000\000\000\000\000\000\000\000",
>> flags = 1,
>> exit_latency = 100,
>> power_usage = 0,
>> target_residency = 200,
>> disabled = false,
>> enter = 0xffffffffa00ab026 <acpi_idle_enter_simple>,
>> enter_dead = 0xffffffffa00aa39c <acpi_idle_play_dead>
>> }
>
> Assembly level analysis:
>
>> RDX: 0000000225c17d03
>
> So EDX is 00000002 and that's the entered state C2.
>
>> RDI: ffffffff81c15540
>> ..
>> crash> info symbol 0xffffffff81c15540
>> clocksource_tsc in section .data
>>
>> crash> disassemble cpuidle_enter_state
>> ...
>> 0xffffffff815af5fc <+60>: callq 0xffffffff8109b360 <ktime_get>
>> 0xffffffff815af601 <+65>: sti
>> 0xffffffff815af602 <+66>: sub %r13,%rax <- here rdi still points to clocksource_tsc
>> 0xffffffff815af605 <+69>: mov %rax,%rdi <- rdi is overwritten by the ktime_get return address
--
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next prev parent reply other threads:[~2015-06-18 9:22 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-17 10:06 cpuidle: Kernel panics with AMD Opteron 6300 entering C2 - clock related Sebastian Parschauer
2015-06-18 9:22 ` Daniel Lezcano [this message]
2015-06-18 10:52 ` Sebastian Parschauer
2015-06-18 11:21 ` Sebastian Parschauer
2015-06-18 13:28 ` Daniel Lezcano
2015-06-18 14:09 ` Sebastian Parschauer
2015-06-18 13:23 ` Daniel Lezcano
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