[BUG] null-pointer deref (perhaps reiserfs3)

[Sven Köhler]

Hi,

on a machine that i can only reach via SSH at the moment, i got a 
null-pointer dereference (see below). The machine runs kernel 2.6.9 
without any additional patches.

It happened, while i was doing a "make install". A command within the 
"installkernel"-script segfaulted. It seems that only the filesystem 
mounted to /boot is affected. Any access to that FS blocks.

Is there any way to recover the situation remotely? I'm thinking about 
unmounting /boot, and running fsck.reiserfs, but i cannot umount the FS, 
since the device is still in use.



Unable to handle kernel NULL pointer dereference at virtual address 00000000
 printing eip:
c018d632
*pde = 00000000
Oops: 0000 [#1]
SMP
Modules linked in: nfsd exportfs lockd sunrpc ipt_state ip_conntrack 
ipt_REJECT ipt_ULOG iptable_filter ip_tables ohci_hcd ehci_hcd uhci_hcd 
rtc usbcore 8250_acpi 8250 serial_core e100 mii ide_cd sr_mod cdrom
CPU:    1
EIP:    0060:[<c018d632>]    Not tainted VLI
EFLAGS: 00010282   (2.6.9)
EIP is at scan_bitmap_block+0x32/0x280
eax: f894f000   ebx: 00000001   ecx: 00000000   edx: 00000000
esi: f894f008   edi: db319c5c   ebp: f7fd9600   esp: db319bf8
ds: 007b   es: 007b   ss: 0068
Process cat (pid: 15917, threadinfo=db318000 task=f47b26d0)
Stack: f3c90000 00008000 00002618 00000001 db319c10 00000000 00000000 
00000000
       00000001 db319c5c 00000000 f7fd9600 c018db60 db319ebc 00000001 
db319c5c
       00000801 00000020 00000020 00000001 00008000 00000800 00000001 
00008000
Call Trace:
 [<c018db60>] scan_bitmap+0x200/0x230
 [<c018ed06>] reiserfs_allocate_blocknrs+0x176/0x4f0
 [<c019bef0>] reiserfs_allocate_blocks_for_region+0x270/0x1660
 [<c01ad843>] search_for_position_by_key+0x1d3/0x400
 [<c01ac0a3>] pathrelse+0x23/0x40
 [<c019dfbc>] reiserfs_prepare_file_region_for_write+0x3bc/0x9d0
 [<c019eb3b>] reiserfs_file_write+0x56b/0x7c0
 [<c01546f8>] vfs_write+0xb8/0x130
 [<c0154841>] sys_write+0x51/0x80
 [<c01041ef>] syscall_call+0x7/0xb
Code: 8b 44 24 34 8b 7c 24 3c 8b 54 24 38 8b 28 8b 0f 8b 85 64 01 00 00 
8b 40 08 89 4c 24 14 8d 34 d0 85 f6 0f 84 2f 02 00 00 8b 56 04 <8b> 02 
a8 04 0f 85 15 02 00 00 0f b7 46 02 31 d2 3b 44 24 44 0f


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