I received the following oops when using the loop driver on kernel
2.4.2-pre2 patched with Jens Axboe's loop4 patch. I believe it occurs
because in loop.c, lo->lo_tsk is only assigned to by the loop thread when
it starts up but it is possible for block requests to be sent to the
loop drivers before this happens.
ksymoops 2.3.7 on i486 2.4.2-pre2-loop4. Options used
-V (default)
-k /proc/ksyms (default)
-l /proc/modules (default)
-o /lib/modules/2.4.2-pre2-loop4/ (default)
-m /boot/System.map-2.4.2-pre2-loop4 (specified)
Feb 9 23:17:38 whitehall1-5 kernel: Unable to handle kernel NULL pointer dereference at virtual address 00000000
Feb 9 23:17:38 whitehall1-5 kernel: c01135fb
Feb 9 23:17:38 whitehall1-5 kernel: *pde = 00000000
Feb 9 23:17:38 whitehall1-5 kernel: Oops: 0002
Feb 9 23:17:38 whitehall1-5 kernel: CPU: 0
Feb 9 23:17:38 whitehall1-5 kernel: EIP: 0010:[<c01135fb>]
Using defaults from ksymoops -t elf32-i386 -a i386
Feb 9 23:17:38 whitehall1-5 kernel: EFLAGS: 00010046
Feb 9 23:17:38 whitehall1-5 kernel: eax: 00000000 ebx: 00000246 ecx: 00000000 edx: 00000246
Feb 9 23:17:38 whitehall1-5 kernel: esi: c38c9c20 edi: 00000000 ebp: c17fdc90 esp: c17fdc8c
Feb 9 23:17:38 whitehall1-5 kernel: ds: 0018 es: 0018 ss: 0018
Feb 9 23:17:38 whitehall1-5 kernel: Process mount (pid: 1006, stackpage=c17fd000)
Feb 9 23:17:38 whitehall1-5 kernel: Stack: c39ef800 00000700 c485282f c39ef800 c38c9c20 c0092000 00000000 c3269860
Feb 9 23:17:38 whitehall1-5 kernel: c1154060 c02521c0 00000000 c38c9c20 00000002 0000001c 00000700 c015e45a
Feb 9 23:17:38 whitehall1-5 kernel: c0246bec 00000000 c38c9c20 c14b4000 c262a460 c17fc000 00000000 c38c9c20
Feb 9 23:17:38 whitehall1-5 kernel: Call Trace: [<c485282f>] [<c015e45a>] [<c015e4c9>] [<c015e757>] [<c01328f5>] [<c48176e0>] [<c48177b7>]
Feb 9 23:17:39 whitehall1-5 kernel: [<c0173998>] [<c017b92e>] [<c0174731>] [<c0174a30>] [<c0143360>] [<c014447b>] [<c0137d36>] [<c481fb20>]
Feb 9 23:17:39 whitehall1-5 kernel: [<c481f533>] [<c481fae0>] [<c01358b9>] [<c0135b14>] [<c481fb20>] [<c481fb20>] [<c01366e6>] [<c481fb20>]
Feb 9 23:17:39 whitehall1-5 kernel: [<c481fb20>] [<c0136501>] [<c013689c>] [<c0108ee3>]
Feb 9 23:17:39 whitehall1-5 kernel: Code: c7 01 00 00 00 00 8b 51 3c 85 d2 75 32 8d 41 3c 8b 15 a8 ef
>>EIP; c01135fb <wake_up_process+b/50> <=====
Trace; c485282f <[loop]loop_make_request+df/1c0>
Trace; c015e45a <generic_make_request+14a/160>
Trace; c015e4c9 <submit_bh+59/80>
Trace; c015e757 <ll_rw_block+217/260>
Trace; c01328f5 <bread+35/70>
Trace; c48176e0 <[fat]fat_read_super+e0/8a0>
Trace; c48177b7 <[fat]fat_read_super+1b7/8a0>
Trace; c0173998 <ide_set_handler+58/60>
Trace; c017b92e <do_rw_disk+de/290>
Trace; c0174731 <ide_wait_stat+91/e0>
Trace; c0174a30 <start_request+190/200>
Trace; c0143360 <destroy_inode+30/40>
Trace; c014447b <iput+16b/170>
Trace; c0137d36 <blkdev_get+e6/100>
Trace; c481fb20 <[vfat]vfat_fs_type+0/17>
Trace; c481f533 <[vfat]vfat_read_super+23/90>
Trace; c481fae0 <[vfat]vfat_dir_inode_operations+0/40>
Trace; c01358b9 <read_super+f9/170>
Trace; c0135b14 <get_sb_bdev+164/1c0>
Trace; c481fb20 <[vfat]vfat_fs_type+0/17>
Trace; c481fb20 <[vfat]vfat_fs_type+0/17>
Trace; c01366e6 <do_mount+186/2c0>
Trace; c481fb20 <[vfat]vfat_fs_type+0/17>
Trace; c481fb20 <[vfat]vfat_fs_type+0/17>
Trace; c0136501 <copy_mount_options+51/b0>
Trace; c013689c <sys_mount+7c/c0>
Trace; c0108ee3 <system_call+33/40>
Code; c01135fb <wake_up_process+b/50>
00000000 <_EIP>:
Code; c01135fb <wake_up_process+b/50> <=====
0: c7 01 00 00 00 00 movl $0x0,(%ecx) <=====
Code; c0113601 <wake_up_process+11/50>
6: 8b 51 3c mov 0x3c(%ecx),%edx
Code; c0113604 <wake_up_process+14/50>
9: 85 d2 test %edx,%edx
Code; c0113606 <wake_up_process+16/50>
b: 75 32 jne 3f <_EIP+0x3f> c011363a <wake_up_process+4a/50>
Code; c0113608 <wake_up_process+18/50>
d: 8d 41 3c lea 0x3c(%ecx),%eax
Code; c011360b <wake_up_process+1b/50>
10: 8b 15 a8 ef 00 00 mov 0xefa8,%edx
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