Re: [RFC][v2][patch 0/12][CFQ-cgroup]Yet another I/O bandwidth controlling subsystem for CGroups based on CFQ

[Andrea Righi <righi.andrea@gmail.com>]

Satoshi UCHIDA wrote:
> Hi, Tsuruta-san.
> 
>> I'm looking forward to your report.

Hi Satoshi,

I'm testing your patch agains latest Linus git and I've got the
following bug. It can be easily reproduced creating a cgroup, switching
the i/o scheduler from cfq to any other and switch back to cfq again.

-Andrea

BUG: unable to handle kernel paging request at ffffffeb
IP: [<c0212dc6>] cfq_cgroup_sibling_tree_add+0x36/0x90
Oops: 0000 [#1] SMP
Modules linked in: i2c_piix4 ne2k_pci 8390 i2c_core

Pid: 3543, comm: bash Not tainted (2.6.26-rc4 #1)
EIP: 0060:[<c0212dc6>] EFLAGS: 00010286 CPU: 0
EIP is at cfq_cgroup_sibling_tree_add+0x36/0x90
EAX: 00000003 EBX: c7704c90 ECX: ffffffff EDX: c7102180
ESI: c7102240 EDI: c7704c80 EBP: c7afbe94 ESP: c7afbe80
 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
Process bash (pid: 3543, ti=c7afa000 task=c7aeda00 task.ti=c7afa000)
Stack: c7704c90 c71022d0 c7ace078 c7704c80 c71020c0 c7afbea8 c021363c
c7ace078
       c7803460 c71020c0 c7afbebc c021360a c7102184 c71020c0 c7102180
c7afbee4
       c02134e0 00000000 c7102184 c72b8ab0 00000001 c7102140 c72b8ab0
c04b8ac0
Call Trace:
 [<c021363c>] ? cfq_cgroup_init_cfq_data+0x7c/0x80
 [<c021360a>] ? cfq_cgroup_init_cfq_data+0x4a/0x80
 [<c02134e0>] ? __cfq_cgroup_init_queue+0x100/0x1e0
 [<c021097b>] ? cfq_init_queue+0xb/0x10
 [<c0204ff8>] ? elevator_init_queue+0x8/0x10
 [<c0205cd0>] ? elv_iosched_store+0x80/0x2b0
 [<c0209379>] ? queue_attr_store+0x49/0x70
 [<c01c488b>] ? sysfs_write_file+0xbb/0x110
 [<c0186276>] ? vfs_write+0x96/0x160
 [<c01c47d0>] ? sysfs_write_file+0x0/0x110
 [<c018696d>] ? sys_write+0x3d/0x70
 [<c0104267>] ? sysenter_past_esp+0x78/0xd1
 =======================
Code: ec 08 8b 82 90 00 00 00 83 e0 fc 89 45 f0 8d 82 90 00 00 00 39 45
f0 75 5f
8d 47 10 89 45 ec 89 c3 31 c0 eb 11 8b 56 7c 8d 41 04 <3b> 51 ec 8d 59
08 0f 43
d8 89 c8 8b 0b 85 c9 75 e9 89 86 90 00
EIP: [<c0212dc6>] cfq_cgroup_sibling_tree_add+0x36/0x90 SS:ESP
0068:c7afbe80
---[ end trace 9701f4859bb53d27 ]---