From: Andi Kleen <andi@firstfloor.org>
To: "Brandeburg, Jesse" <jesse.brandeburg@intel.com>
Cc: linux-kernel@vger.kernel.org,
oprofile-list@lists.sourceforge.net, netdev@vger.kernel.org,
rusty@rustcorp.com.au
Subject: Re: [BUG 2.6.30-rc1] panic when loading oprofile
Date: Fri, 15 May 2009 14:41:26 +0200 [thread overview]
Message-ID: <87fxf6pmh5.fsf@basil.nowhere.org> (raw)
In-Reply-To: <alpine.WNT.2.00.0905131327430.7052__41366.1100705669$1242253861$gmane$org@jbrandeb-desk1.amr.corp.intel.com> (Jesse Brandeburg's message of "Wed, 13 May 2009 15:30:07 -0700 (Pacific Daylight Time)")
"Brandeburg, Jesse" <jesse.brandeburg@intel.com> writes:
Hi Jesse,
> when starting a profile run on the latest net-next kernel, I'm currently
> trying to reproduce on 2.6.30-rc5 stock.
Were you able to reproduce it?
>
> config available upon request, arch=x86_64, recent (F10 or newer) oprofile
> userspace.
it looks like two bugs: oprofile didn't catch a NMI that belongs to
it (most likely) and the NMI watchdog referenced a NULL pointer
while processing an NMI.
Did you have the nmi watchdog enabled on the command line?
>
> BUG: unable to handle kernel NULL pointer dereference at (null)
> IP: [<ffffffff8066080a>] nmi_watchdog_tick+0xa1/0x1d6
I don't get the same code as you. But the oopsing instruction in your
oops is
2b:* 44 0f a3 28 bt %r13d,(%rax) <-- trapping instruction
with rax == 0 and I suspect it's one of the new cpu mask checks
I would try reverting
fcc5c4a2feea3886dc058498b28508b2731720d5
2f537a9f8e82f55c241b002c8cfbf34303b45ada
fcef8576d8a64fc603e719c97d423f9f6d4e0e8b
and see which one causes it. That would only fix the NMI watchdog bug
of course.
The oprofile not catching a event problem would be still open then.
I think the checks for overflowed counters are not 100% perfect
so that could happen. I have some patches in the works to use the new
global status register on arch perfmon 2, with that the overflow
check is somewhat more reliable. But that's more work.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next parent reply other threads:[~2009-05-15 12:41 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <alpine.WNT.2.00.0905131327430.7052__41366.1100705669$1242253861$gmane$org@jbrandeb-desk1.amr.corp.intel.com>
2009-05-15 12:41 ` Andi Kleen [this message]
2009-05-16 23:20 ` [BUG 2.6.30-rc1] panic when loading oprofile Andrew Morton
2009-05-17 8:38 ` Andi Kleen
2009-05-20 7:13 ` Brandeburg, Jesse
2009-05-20 11:27 ` Andi Kleen
2009-05-13 22:30 Brandeburg, Jesse
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