netdev - Re: [Bugme-new] [Bug 13553] New: When NETCONSOLE is enabled in kernel, computer crashes after 120seconds (approx)

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Message-ID: <20090624010501.GB27384@localhost.localdomain>
Date:	Tue, 23 Jun 2009 21:05:01 -0400
From:	Neil Horman <nhorman@...driver.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	netdev@...r.kernel.org, bugzilla-daemon@...zilla.kernel.org,
	bugme-daemon@...zilla.kernel.org, hilld@...arystorm.net
Subject: Re: [Bugme-new] [Bug 13553] New: When NETCONSOLE is enabled in
	kernel, computer crashes after 120seconds (approx)

On Tue, Jun 23, 2009 at 02:07:43PM -0700, Andrew Morton wrote:
> 
> (switched to email.  Please respond via emailed reply-to-all, not via the
> bugzilla web interface).
> 
> On Wed, 17 Jun 2009 01:55:54 GMT
> bugzilla-daemon@...zilla.kernel.org wrote:
> 
> > http://bugzilla.kernel.org/show_bug.cgi?id=13553
> > 
> >            Summary: When NETCONSOLE is enabled in kernel, computer crashes
> >                     after 120seconds (approx)
> >            Product: Networking
> >            Version: 2.5
> >     Kernel Version: 2.6.29.4, 2.6.30
> >           Platform: All
> >         OS/Version: Linux
> >               Tree: Mainline
> >             Status: NEW
> >           Severity: high
> >           Priority: P1
> >          Component: Other
> >         AssignedTo: acme@...stprotocols.net
> >         ReportedBy: hilld@...arystorm.net
> >         Regression: No
> > 
> > 
> 
> > 00:00.0 Host bridge: Intel Corporation 440GX - 82443GX Host bridge
> > 00:01.0 PCI bridge: Intel Corporation 440GX - 82443GX AGP bridge
> > 00:07.0 ISA bridge: Intel Corporation 82371AB/EB/MB PIIX4 ISA (rev 02)
> > 00:07.1 IDE interface: Intel Corporation 82371AB/EB/MB PIIX4 IDE (rev 01)
> > 00:07.2 USB Controller: Intel Corporation 82371AB/EB/MB PIIX4 USB (rev 01)
> > 00:07.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 02)
> > 00:0b.0 SCSI storage controller: Adaptec AIC-7896U2/7897U2
> > 00:0b.1 SCSI storage controller: Adaptec AIC-7896U2/7897U2
> > 00:0d.0 Ethernet controller: Intel Corporation 82557/8/9/0/1 Ethernet Pro 100
> > (rev 08)
> > 00:12.0 Ethernet controller: Realtek Semiconductor Co., Ltd.
> > RTL-8139/8139C/8139C+ (rev 10)
> > 01:00.0 VGA compatible controller: ATI Technologies Inc Rage 128 RL/VR AGP
> > 
> > ------- Comment #2 From David Hill 2009-06-17 02:55:56 (-) [reply] -------
> > 
> > With NETCONSOLE enabled, if I type:
> > ethtool -s eth1 speed 100 duplex full autoneg on
> > 
> > the computer freezes with kernel 2.6.29.4 and 2.6.30...
> > 
> > I can reproduce it anytime you want.
> > 
> 
> Interesting.  I wonder what the significance is of the 120 seconds.  I
> see no such timers in e100.c.  Does the networking core have timers on
> such intervals?
> 
My guess is the 120 seconds has less to do with the driver, and more to do with
some other periodic event in the kernel that triggers a message getting written
to the console, which in turn triggers whatever deadlock it is thats getting hit
here.  I imagine we could diagnose it pretty quick if a stack trace or vmcore
could be captured on this.  David, can you enable the NMI watchdog on this
system to trigger a panic on the system after a deadlock?  Then if you could
enable a second serial console, or setup kdump to capture a vmcore on this
system, we should be able to  figure out whats going on.  My guess is that in
the e100 driver we're taking a lock in the ethtool set path, then calling
printk, which winds up recursing into the driver, trying to take the same lock
again.  A stack trace will tell us for certain.

Regards
Neil

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