Host kernel bug with UML

From: David Coulson (
Date: Fri Sep 20 2002 - 11:15:42 EST

I have been experiencing VM problems with the host linux kernel when
running UMLs. These have generally been swap_dup errors under vanilla
kernel trees, so I proceeded to patch my kernel with the rmap patch to
see if this would make any difference.

I experienced the following problem this afternoon, on a system running
2.4.19-ck7-rmap, which required a reboot before UML would continue to
work correctly. If anyone needs more information, let me know - I can't
actually reproduce this on demand, but it seems to occur reasonably
frequently. I'm confident that it is not a hardware issue, as I have
tested the system under load, and have had it happily swap out a couple
of Gb to disk, then back into RAM without any problems. Someone
suggested that it may be because I'm swapping to a LVM LV, but I've no
idea if that is actually a contributing factor or not.

kernel BUG at mmap.c:732!
invalid operand: 0000
CPU: 0
EIP: 0010:[<c012af18>] Not tainted
Using defaults from ksymoops -t elf32-i386 -a i386
EFLAGS: 00010202
eax: eb93ff9c ebx: ec689140 ecx: ec689638 edx: ec689620
esi: 40155000 edi: ec689638 ebp: c0dc6dc0 esp: eb93ff60
ds: 0018 es: 0018 ss: 0018
Process linux-4um-1G (pid: 8994, stackpage=eb93f000)
Stack: c0dc6dc0 00001000 00001000 ffff0001 c012b2ba c0dc6dc0 40155000
        c0dc6dc0 c0dc6ddc 00001000 ffff0001 c0107e62 eb93ffc4 9a8e3d28
        c012b50e c0dc6dc0 40155000 00001000 eb93e000 00000000 00000010
Call Trace: [<c012b2ba>] [<c0107e62>] [<c012b50e>] [<c0108a1b>]
Code: 0f 0b dc 02 21 cd 25 c0 89 d8 eb 0c 8b 44 24 1c c7 00 00 00

>>EIP; c012af18 <find_vma_prev+90/b0> <=====

>>eax; eb93ff9c <_end+2b5e8cec/384aad50>
>>ebx; ec689140 <_end+2c331e90/384aad50>
>>ecx; ec689638 <_end+2c332388/384aad50>
>>edx; ec689620 <_end+2c332370/384aad50>
>>edi; ec689638 <_end+2c332388/384aad50>
>>ebp; c0dc6dc0 <_end+a6fb10/384aad50>
>>esp; eb93ff60 <_end+2b5e8cb0/384aad50>

Trace; c012b2ba <do_munmap+56/274>
Trace; c0107e62 <sys_sigreturn+e6/114>
Trace; c012b50e <sys_munmap+36/54>
Trace; c0108a1b <system_call+33/38>

Code; c012af18 <find_vma_prev+90/b0>
00000000 <_EIP>:
Code; c012af18 <find_vma_prev+90/b0> <=====
    0: 0f 0b ud2a <=====
Code; c012af1a <find_vma_prev+92/b0>
    2: dc 02 faddl (%edx)
Code; c012af1c <find_vma_prev+94/b0>
    4: 21 cd and %ecx,%ebp
Code; c012af1e <find_vma_prev+96/b0>
    6: 25 c0 89 d8 eb and $0xebd889c0,%eax
Code; c012af23 <find_vma_prev+9b/b0>
    b: 0c 8b or $0x8b,%al
Code; c012af25 <find_vma_prev+9d/b0>
    d: 44 inc %esp
Code; c012af26 <find_vma_prev+9e/b0>
    e: 24 1c and $0x1c,%al
Code; c012af28 <find_vma_prev+a0/b0>
   10: c7 00 00 00 00 00 movl $0x0,(%eax)


David Coulson                                     

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This archive was generated by hypermail 2b29 : Mon Sep 23 2002 - 22:00:31 EST