From: Glauber de Oliveira Costa <gcosta@redhat.com>
To: Keir Fraser <Keir.Fraser@cl.cam.ac.uk>
Cc: xen-devel@lists.xensource.com
Subject: Re: [PATCH] BUG() on soft lockup upon suspend/resume
Date: Mon, 9 Oct 2006 21:29:10 -0300 [thread overview]
Message-ID: <20061010002910.GC28540@redhat.com> (raw)
In-Reply-To: <C1508A1A.2405%Keir.Fraser@cl.cam.ac.uk>
>
> > In systems with vcpu > 1, a BUG due to a detected soft lockup seems to be
> > triggered after system resume/suspend. This is probably due to the lack of
> > seqlocking around the region that does the local time processing.
>
> We do SMP save/restore tests regularly and do not see this issue. It ought
> to be avoided by the fact that, when we bring up a CPU, we
> touch_softlockup_watchdog() in cpu_bringup(), before enabling interrupts.
> For CPU0 on resume, the touch is done in time_resume() in
> arch/i386/kernel/time-xen.c.
This happens not only (once) when the system comes back. It do happen a
lot after it. So even if the first touch is right, I suspect this issue
is more related to a situation in which we are already resumed for a
long time, with all set up
>
> I think we need to understand the issue you are hitting a bit more before
> deciding on the right fix.
Right, here it goes more info:
I'm on a 8-way x86_64 machine, and This is the sort of info I see
repeatedly:
BUG: soft lockup detected on CPU#1!
Call Trace:
<IRQ> [<ffffffff802ace9d>] softlockup_tick+0xf8/0x113
[<ffffffff8026d591>] timer_interrupt+0x38a/0x3d8
[<ffffffff80210e87>] handle_IRQ_event+0x2d/0x60
[<ffffffff802ad1e6>] __do_IRQ+0xa5/0x107
[<ffffffff8028be7a>] _local_bh_enable+0x61/0xc5
[<ffffffff8026b4c9>] do_IRQ+0xe7/0xf5
[<ffffffff8039386e>] evtchn_do_upcall+0x86/0xe0
[<ffffffff8025e2a2>] do_hypervisor_callback+0x1e/0x2c
<EOI> [<ffffffff802063aa>] hypercall_page+0x3aa/0x1000
[<ffffffff802063aa>] hypercall_page+0x3aa/0x1000
[<ffffffff8026cb13>] raw_safe_halt+0x84/0xa8
[<ffffffff8026a121>] xen_idle+0x38/0x4a
[<ffffffff80248e66>] cpu_idle+0x97/0xba
It obviously never happen on CPU#0, but I see it on all others (vcpus=4)
If you have any other opinion on what else may be causing this, it's
very welcome. I'll keep investigating.
--
Glauber de Oliveira Costa
Red Hat Inc.
"Free as in Freedom"
next prev parent reply other threads:[~2006-10-10 0:29 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-09 21:22 [PATCH] BUG() on soft lockup upon suspend/resume Glauber de Oliveira Costa
2006-10-09 22:22 ` Keir Fraser
2006-10-10 0:29 ` Glauber de Oliveira Costa [this message]
2006-10-10 10:06 ` Keir Fraser
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