"John Stoffel" [off-list ref] wrote:

Here's an oops and hang from /var/log/messages that happened the other
evening.  It kicked in at 4am or so.  This was running 2.5.70-mm3 SMP,
PREEMPT, no ACPI, RAID1 on one pair of disks, not root or /boot.

Here's the messages I got in the messages file.  The system was
completely hung and needed to be reset to recover:

Unable to handle kernel paging request at virtual
 address 6b6b6b6b
 printing eip:
c0133477
*pde = 00000000
Oops: 0000 [#1]
PREEMPTSMP DEBUG_PAGEALLOC
CPU:    1
EIP:    0060:[detach_pid+23/304]    Not tainted VLI
EIP:    0060:[<c0133477>]    Not tainted VLI
EFLAGS: 00010046
EIP is at detach_pid+0x17/0x130
eax: dfd30050   ebx: 6b6b6b6b   ecx: dfd30100   edx: 6b6b6b6b
esi: e3cc6000   edi: 00000000   ebp: 00000000   esp: e3cc7f08
ds: 007b   es: 007b   ss: 0068
Process makewhatis (pid: 2446, threadinfo=e3cc6000 task=e4117000)
Stack: dfd30000 e3cc6000 00000000 c0123a79 dfd30000 c0123bb3 dfd30000 dfd30000 
       dfd305c4 dfd30000 00000a07 bffff5c8 c01258cd dfd30000 ea854a74 bffff350 
       dfd300a4 dfd30000 e4117000 00000000 c0125075 dfd30000 bffff5c8 00000000 
Call Trace:
 [__unhash_process+57/176] __unhash_process+0x39/0xb0
 [<c0123a79>] __unhash_process+0x39/0xb0
 [release_task+195/560] release_task+0xc3/0x230
 [<c0123bb3>] release_task+0xc3/0x230
 [wait_task_zombie+397/432] wait_task_zombie+0x18d/0x1b0
 [<c01258cd>] wait_task_zombie+0x18d/0x1b0
 [sys_wait4+357/640] sys_wait4+0x165/0x280
 [<c0125c75>] sys_wait4+0x165/0x280
 [default_wake_function+0/32] default_wake_function+0x0/0x20
 [<c011da40>] default_wake_function+0x0/0x20
 [default_wake_function+0/32] default_wake_function+0x0/0x20
 [<c011da40>] default_wake_function+0x0/0x20
 [syscall_call+7/11] syscall_call+0x7/0xb
 [<c010af1f>] syscall_call+0x7/0xb

Code: 51 08 52 e8 8c cd fe ff 58 5b c3 89 f6 8d bc 27 00 00 00 00 57 56 53 89 d3 8d 14 9b 8d 04 d0 8d 88 b0 00 00 00 8b 59 08 8b 51 04 <39> 0a 74 08 0f 0b 8c 00 c8 8f 3a c0 8b 80 b0 00 00 00 39 48 04 

This appears to be a visitation from the Great Unsolved Bug of the 2.5
series.  Someone playing with a freed task_struct.

Correct me if I'm wrong, but this has only ever been seen with
CONFIG_PREEMPT=y?
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