Re: Linux 2.6.24-rc5 x86 architecture no longer Oopses...

[Trond Myklebust <trond.myklebust@fys.uio.no>]

On Thu, 2007-12-20 at 14:54 -0800, Andrew Morton wrote:
> On Thu, 20 Dec 2007 17:40:47 -0500
> Trond Myklebust <trond.myklebust@fys.uio.no> wrote:
> 
> > I just got the following interesting behaviour. Never mind why the
> > original Oops (I was testing some experimental RPC patches), but there
> > appears to be a BUG_ON() triggered inside the dump() call.
> > 
> > Oops occurred with a build based on this afternoon's git tree from Linus
> > (v2.6.24-rc5-317-gfaa4877)...
> > 
> > Cheers
> >   Trond
> > ---------
> > 
> > BUG: unable to handle kernel NULL pointer dereference at virtual address 00000000
> > printing eip: f8bcc8b3 *pde = 00000000 
> > BUG: using smp_processor_id() in preemptible [00000001] code: mount.nfs4/2970
> > caller is die+0x59/0x202
> > Pid: 2970, comm: mount.nfs4 Not tainted 2.6.24-rc5-ga747a088 #1
> >  [<c0405170>] show_trace_log_lvl+0x1a/0x2f
> >  [<c0405a76>] show_trace+0x12/0x14
> >  [<c0405dc6>] dump_stack+0x6c/0x72
> >  [<c04e4cd8>] debug_smp_processor_id+0xa0/0xb4
> >  [<c0405462>] die+0x59/0x202
> >  [<c05b3e7d>] do_page_fault+0x557/0x63e
> >  [<c05b252a>] error_code+0x72/0x78
> >  [<f8bd821c>] rpcb_create+0x7c/0x84 [sunrpc]
> >  [<f8bd8552>] rpcb_register+0x127/0x18c [sunrpc]
> >  [<f8bd31d2>] svc_register+0xcf/0x14c [sunrpc]
> >  [<f8bd399f>] __svc_create+0x19a/0x1b3 [sunrpc]
> >  [<f8bd3b21>] svc_create+0x13/0x15 [sunrpc]
> >  [<f8c74beb>] nfs_callback_up+0x71/0x126 [nfs]
> >  [<f8c53cfe>] nfs_get_client+0x14e/0x3a2 [nfs]
> >  [<f8c53f88>] nfs4_set_client+0x36/0x14f [nfs]
> >  [<f8c54739>] nfs4_create_server+0x8e/0x36c [nfs]
> >  [<f8c5c6f1>] nfs4_get_sb+0x2ef/0x3f3 [nfs]
> >  [<c0477e40>] vfs_kern_mount+0x7d/0xf1
> >  [<c0477f02>] do_kern_mount+0x37/0xbd
> >  [<c048a6fb>] do_mount+0x5c3/0x61d
> >  [<c048a7c4>] sys_mount+0x6f/0xa9
> >  [<c04040b2>] sysenter_past_esp+0x5f/0xa5
> >  =======================
> 
> Yes - I don't know why the smp_processor_id() test has suddenly started
> triggering in there.
> 
> I have a sledgehammer fix (below) which Ingo went all complicated about and
> I assumed he had it in hand, but I can't see any patches anywhere?
> 
> I'd expect the kernel to spit that warning and then proceed with the usual
> oops report - that's what it did in Miles Lane's case.  But it seems in
> your case that the whole oops report simply vanished?

No. I found what I assume is the remainder of the original a couple of
pages further down...

Trond