Re: ulogd unaligned trap
On 01/24/06 11:21:46AM -0500, Jay Estabrook wrote:
> On Sat, Jan 21, 2006 at 07:25:47PM -0500, Jim Crilly wrote:
> > On 01/21/06 09:45:15PM +0000, Carlos Rodrigues wrote:
> > > Hi!
> > >
> > > I have a couple of Alpha machines (XP1000 and ES40) which spit this
> > > message regularly to /var/log/messages and the console:
> > >
> > > Jan 21 21:41:05 ulisses kernel: ulogd(26459): unaligned trap at
> > > 00000200001e2ce8: 000002000020a0e5 28 4
> > > Jan 21 21:41:05 ulisses kernel: ulogd(26459): unaligned trap at
> > > 00000200001e2d64: 000002000020a0e9 28 4
> > > Jan 21 21:41:05 ulisses kernel: ulogd(26459): unaligned trap at
> > > 00000200001e2da8: 000002000020a0e1 28 3
> > > Jan 21 21:41:05 ulisses kernel: ulogd(26459): unaligned trap at
> > > 00000200001e2df4: 000002000020a0e1 28 2
> > >
> > > I think (not sure) this started happening since the latest kernel
> > > security update.
> > >
> > > Both machines are running sarge, with the stock (debian) 2.4.27 kernel
> > > (smp, in the ES40).
> > >
> > > I don't think this is affecting the operation of ulogd, but I'm not
> > > sure. Anyways, I reported this to the BTS.
> > >
> > > Any ideas?
> > >
> >
> > Ulogd will keep running just fine. What's happening is it's attempting
> > to access memory that's not aligned properly, the hardware complains
> > and the kernel fixes the access so the hardware is happy. It cause
> > a bit of a slowdown since the kernel has to fix up the operation,
> > but it doesn't cause any other problems.
>
> It can be more than a little slowdown, if it happens a lot.
>
> Check for the frequency via:
>
> cat /proc/cpuinfo | grep unalign
>
> and see how often/how much it changes.
>
> BTW, the addresses spit out in the message look like they are from
> a module, which may make tracking it down a bit more difficult...
>
> Good luck.
>
> --Jay++
>
You probbaly know this, but ulogd is a userspace log daemon for
netfilter that uses a netlink socket for it's input from netfilter. So
I guess the alignment problems could be netfilter, the netlink code
or ulogd itself.
Jim.
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