Re: Unable to handle kernel NULL pointer dereference at virtual address 00000000

[Ray Van Dolson <rayvd@digitalpath.net>]

Just a follow-up on this.  Things seem to run better (no crashes yet after
two days of runtime) after booting with nosmp noapic.

Any issues with the MPPE or CryptoAPI code that might only be triggered
when running in SMP mode?

Ray

On Wed, Dec 15, 2004 at 08:36:51AM -0800, Ray Van Dolson wrote:
> On Wed, Dec 15, 2004 at 10:29:43AM -0600, Matt Domsch wrote:
> > These messages I have gotten for years. They're debugging messages,
> > as a result of:
> > register_netdevice( alloc_divert_blk( (sees it's not an ethernet device, )
> > printk's the message )
> >
> > So I believe they're harmless.
> This is what I was thinking too. I see plenty of these messages that do
> not result in crashes.
>
> > > ksymoops output of problem:
> > > Unable to handle kernel NULL pointer dereference
> > > 00000000
> > > *pde = 00000000
> > > Oops: 0000 [#1]
> > > CPU: 2
> > > EIP: 0060:[<00000000>] Not tainted VLI
> > > Using defaults from ksymoops -t elf32-i386 -a i386
> > > EFLAGS: 00010286 (2.6.9)
> > > eax: ed13b000 ebx: d1d0a000 ecx: c029e9de edx: f795ef40
> > > esi: d1d0a000 edi: 00000000 ebp: e2f30080 esp: d2b0dea0
> > > ds: 007b es: 007b ss: 0068
> > > Stack: c02a205a ed13b000 00000000 c02a122c d1d0a000 13208a2e c040956f
> > > d1d0a000 d1d0a00c e2f30080 00000000 c029cda9 d1d0a000 e2f30080 00000000
> > > c01552cd e2f30080 00000010 00000004 00000004 c0166aa0 e2f30080 00000000
> > > 00000000
> > > Call Trace: [<c02a205a>] pty_chars_in_buffer+0x2c/0x49 [<c02a122c>]
> > > normal_poll+0xed/0x150 [<c040956f>] schedule_timeout+0x75/0xbf
> > > [<c029cda9>] tty_poll+0xa0/0xb0 [<c01552cd>] fget+0x49/0x5e [<c0166aa0>]
> > > do_select+0x269/0x2c6 [<c0166691>] __pollwait+0x0/0xc7 [<c0166dd5>]
> > > sys_select+0x2b3/0x4c6 [<c0105971>] sysenter_past_esp+0x52/0x71
> > > Code: Bad EIP value.
> > It looks like pty_chars_in_buffer() dereferenced a NULL function
> > pointer, but I don't see how that can be, the one deference is tested
> > for NULL before doing so.
> >
> > I can't rule out the ppp_mppe code, but I haven't seen this crash
> > before myself. Does this happen on simlar systems that aren't running
> > poptop?
> >
> > Thanks,
> > Matt
> Fortunately we use the DL140 server pretty widely here. None of the
> non-poptop servers exhibit this problem. Every single one of them that has
> been used as a Poptop server however does exhibit this issue. It seems to
> happen more frequenly on the machines with a higher number of users
> connected.
>
> I have switched one of the servers (the one with the highest load) to use
> Jan Dubiec's MPPC/MPPE patches for ppp 2.4.3 and Kernel 2.6.9. We'll see
> how that goes.
>
> Any information I can provide or something I can do on my end to better
> trace this down?
>
> Ray