From: Avi Kivity <avi@redhat.com>
To: Sasha Levin <levinsasha928@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
"H. Peter Anvin" <hpa@zytor.com>, Dave Jones <davej@redhat.com>,
kvm@vger.kernel.org,
"linux-kernel@vger.kernel.org List"
<linux-kernel@vger.kernel.org>
Subject: Re: CPU softlockup due to smp_call_function()
Date: Thu, 05 Apr 2012 15:24:54 +0300 [thread overview]
Message-ID: <4F7D8F16.9090904@redhat.com> (raw)
In-Reply-To: <CA+1xoqeqyFT0eHS2k+vskPFQ-5gJ_Uq1HVsq2DA2sS1uN9C0vw@mail.gmail.com>
On 04/04/2012 11:12 PM, Sasha Levin wrote:
> Hi all,
>
> I've starting seeing soft lockups resulting from smp_call_function()
> calls. I've attached two different backtraces of this happening with
> different code paths.
>
> This is running inside a KVM guest with the trinity fuzzer, using
> today's linux-next kernel.
>
> [ 6540.134009] BUG: soft lockup - CPU#0 stuck for 22s! [kworker/u:1:38]
> [ 6540.134048] irq event stamp: 286811770
> [ 6540.134048] hardirqs last enabled at (286811769):
> [<ffffffff82669e74>] restore_args+0x0/0x30
> [ 6540.134048] hardirqs last disabled at (286811770):
> [<ffffffff8266b3ea>] apic_timer_interrupt+0x6a/0x80
> [ 6540.134048] softirqs last enabled at (286811768):
> [<ffffffff810b746e>] __do_softirq+0x16e/0x190
> [ 6540.134048] softirqs last disabled at (286811749):
> [<ffffffff8266bdec>] call_softirq+0x1c/0x30
> [ 6540.134048] CPU 0
> [ 6540.134048] Pid: 38, comm: kworker/u:1 Tainted: G W
> 3.4.0-rc1-next-20120404-sasha-dirty #72
> [ 6540.134048] RIP: 0010:[<ffffffff8111f30e>] [<ffffffff8111f30e>]
> smp_call_function_many+0x27e/0x2a0
>
This cpu is waiting for some other cpu to process a function (likely
rps_trigger_softirq(), from the trace). Can you get a backtrace on all
cpus when this happens?
It would be good to enhance smp_call_function_*() to do this
automatically when it happens - it's spinning there anyway, so it might
as well count the iterations and NMI the lagging cpu if it waits for too
long.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2012-04-05 12:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-04 20:12 CPU softlockup due to smp_call_function() Sasha Levin
2012-04-05 4:06 ` Milton Miller
2012-04-05 8:25 ` Sasha Levin
2012-04-05 12:24 ` Avi Kivity [this message]
2012-04-05 12:32 ` Sasha Levin
2012-04-05 12:51 ` Avi Kivity
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