linux-kernel - Re: kvm deadlock

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Date:	Wed, 14 Dec 2011 16:27:53 +0200
From:	Avi Kivity <avi@...hat.com>
To:	Marcelo Tosatti <mtosatti@...hat.com>
CC:	Nate Custer <nate@...nel.net>, kvm@...r.kernel.org,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Jens Axboe <axboe@...nel.dk>
Subject: Re: kvm deadlock

On 12/14/2011 04:06 PM, Marcelo Tosatti wrote:
> On Wed, Dec 14, 2011 at 04:02:48PM +0200, Avi Kivity wrote:
> > On 12/14/2011 04:00 PM, Marcelo Tosatti wrote:
> > > The other traces have apparently bogus NMI interrupts, but it might be a
> > > software bug, OK.
> > 
> > These are from sysrq-blah, no?  I'm looking at them now.
>
> I don't know. Its a hang ? It could be memory corruption (of the timer
> olist) instead of a bogus NMI actually, the second.

Looks like lots of cpus are waiting on the smp_call_function_single()
lock.  Looks like rcu is complaining:


[ 4959.814010]  [<ffffffff81252e47>] __const_udelay+0x2c/0x2e
[ 4959.814017]  [<ffffffff81027449>]
native_safe_apic_wait_icr_idle+0x31/0x3d
[ 4959.814024]  [<ffffffff81027f11>]
__default_send_IPI_dest_field.constprop.0+0x23/0x5d
[ 4959.814032]  [<ffffffff81027f93>]
default_send_IPI_mask_sequence_phys+0x48/0x97
[ 4959.814039]  [<ffffffff81089848>] ? tick_nohz_handler+0xdf/0xdf
[ 4959.814044]  [<ffffffff8102b561>] physflat_send_IPI_all+0x17/0x19
[ 4959.814052]  [<ffffffff81028102>]
arch_trigger_all_cpu_backtrace+0x57/0x89
[ 4959.814057]  [<ffffffff810c7711>] __rcu_pending+0x89/0x328
[ 4959.814063]  [<ffffffff81089848>] ? tick_nohz_handler+0xdf/0xdf
[ 4959.814067]  [<ffffffff810c7e0a>] rcu_check_callbacks+0x88/0xb9
[ 4959.814071]  [<ffffffff8106aeba>] update_process_times+0x3f/0x75

Maybe the core issue is that CPU 3 is spinning in do_insn_fetch() and
denying rcu grace periods.  Nate, can you provide a few more dumps (this
is looking at the second paste, so more of the same)?

-- 
error compiling committee.c: too many arguments to function

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