pppd oopses current linu's git tree on disconnect

[Diego Calleja <diegocg@gmail.com>]

I got this on my log files (56k serial modem, pentium 3 smp machine, the
machine didn't hang, in fact I could connect again to send this bug
report). If needed, here's the dmesg: http://www.terra.es/personal/diegocg/dmesg
and .config: http://www.terra.es/personal/diegocg/.config. I've never seen
this so I assumed it could be a problem with the "TTY layer buffering revamp"

Jan 18 22:07:23 estel pppd[5338]: Serial link appears to be disconnected.
Jan 18 22:07:23 estel pppd[5338]: Connect time 296.0 minutes.
Jan 18 22:07:23 estel pppd[5338]: Sent 18290428 bytes, received 40448937 bytes.
Jan 18 22:07:23 estel pppd[5338]: Script /etc/ppp/ip-down started (pid 8044)
Jan 18 22:07:23 estel pppd[5338]: sent [LCP TermReq id=0x2 "Peer not responding"]
Jan 18 22:07:23 estel pppd[5338]: rcvd [LCP TermReq id=0x2 "Peer not responding"]
Jan 18 22:07:23 estel pppd[5338]: sent [LCP TermAck id=0x2]
Jan 18 22:07:23 estel pppd[5338]: rcvd [LCP TermAck id=0x2]
Jan 18 22:07:23 estel pppd[5338]: Connection terminated.
Jan 18 22:07:24 estel kernel: Unable to handle kernel paging request at virtual address f554fbf8
Jan 18 22:07:24 estel kernel:  printing eip:
Jan 18 22:07:24 estel kernel: c01fb9e7
Jan 18 22:07:24 estel kernel: *pde = 0043e067
Jan 18 22:07:24 estel kernel: *pte = 3554f000
Jan 18 22:07:24 estel kernel: Oops: 0000 [#1]
Jan 18 22:07:24 estel kernel: PREEMPT SMP DEBUG_PAGEALLOC
Jan 18 22:07:24 estel kernel: Modules linked in: ipt_REJECT xt_tcpudp radeon lp thermal fan button processor ac ipt_MASQUERADE iptable_nat ip
_nat ip_conntrack iptable_filter ip_tables x_tables usbhid parport_pc parport pcspkr floppy ohci_hcd usbcore e100 ide_cd cdrom unix
Jan 18 22:07:24 estel kernel: CPU:    1
Jan 18 22:07:24 estel kernel: EIP:    0060:[tty_buffer_free_all+35/73]    Not tainted VLI
Jan 18 22:07:24 estel kernel: EFLAGS: 00010282   (2.6.16-rc1)
Jan 18 22:07:24 estel kernel: EIP is at tty_buffer_free_all+0x23/0x49
Jan 18 22:07:24 estel kernel: eax: 0000000a   ebx: efab57f8   ecx: 3421a000   edx: f554fbf8
Jan 18 22:07:24 estel kernel: esi: efab57f8   edi: 00000000   ebp: c1aedea8   esp: c1aedea4
Jan 18 22:07:24 estel kernel: ds: 007b   es: 007b   ss: 0068
Jan 18 22:07:24 estel kernel: Process pppd (pid: 5338, threadinfo=c1aed000 task=f407dac0)
Jan 18 22:07:24 estel kernel: Stack: <0>00000000 c1aedec0 c01fd737 00000001 efab57f8 00000001 00000000 c1aedf54
Jan 18 22:07:24 estel kernel:        c01ff251 f43c7f4c 00aedee8 00000000 00000000 00000001 00000000 00000000
Jan 18 22:07:24 estel kernel:        00000001 c1aedef0 c02c3d79 c1aedf18 c01465ca 0808b81c f0cb7c10 f465ae04
Jan 18 22:07:24 estel kernel: Call Trace:
Jan 18 22:07:24 estel kernel:  [show_stack_log_lvl+170/181] show_stack_log_lvl+0xaa/0xb5
Jan 18 22:07:24 estel kernel:  [show_registers+306/414] show_registers+0x132/0x19e
Jan 18 22:07:24 estel kernel:  [die+360/493] die+0x168/0x1ed
Jan 18 22:07:24 estel kernel:  [do_page_fault+921/1239] do_page_fault+0x399/0x4d7
Jan 18 22:07:24 estel kernel:  [error_code+79/84] error_code+0x4f/0x54
Jan 18 22:07:24 estel kernel:  [release_mem+499/512] release_mem+0x1f3/0x200
Jan 18 22:07:24 estel kernel:  [release_dev+1651/1719] release_dev+0x673/0x6b7
Jan 18 22:07:24 estel kernel:  [tty_release+18/28] tty_release+0x12/0x1c
Jan 18 22:07:24 estel kernel:  [__fput+171/362] __fput+0xab/0x16a
Jan 18 22:07:24 estel kernel:  [fput+23/27] fput+0x17/0x1b
Jan 18 22:07:24 estel kernel:  [filp_close+81/91] filp_close+0x51/0x5b
Jan 18 22:07:24 estel kernel:  [sys_close+115/135] sys_close+0x73/0x87
Jan 18 22:07:24 estel kernel:  [sysenter_past_esp+84/117] sysenter_past_esp+0x54/0x75
Jan 18 22:07:24 estel kernel: Code: d8 5b 5e 5f 5d c3 90 90 55 89 e5 53 89 c3 eb 0f 8b 02 89 83 3c 01 00 00 89 d0 e8 8e 65 f5 ff 8b 93 3c 01
00 00 85 d2 75 e7 eb 0f <8b> 02 89 83 44 01 00 00 89 d0 e8 73 65 f5 ff 8b 93 44 01 00 00