Re: Process irqbalance: BUG: unable to handle kernel paging request - with 2.6.32.18 pv-ops & xen 4.0.1

[Jeremy Fitzhardinge <jeremy@goop.org>]

 On 09/02/2010 09:15 AM, Bruce Edge wrote:
> On Tue, Aug 31, 2010 at 11:17 AM, Bruce Edge <bruce.edge@gmail.com
> <mailto:bruce.edge@gmail.com>> wrote:
>
>
>     On Tue, Aug 31, 2010 at 11:00 AM, Jeremy Fitzhardinge
>     <jeremy@goop.org <mailto:jeremy@goop.org>> wrote:
>
>          On 08/30/2010 04:12 PM, Bruce Edge wrote:
>         > Using Jeremy's latest 2.6.32 pv-ops kernel for both dom0 and
>         domU, I
>         > get this BUG at domU boot time.
>         >
>         > [   14.780699] BUG: unable to handle kernel paging request at
>         > 00000002dd253558
>         > [   14.780787] RAX: 0000000000000000 RBX: 0000000000000020 RCX:
>         > 0000000000000020
>         > [   14.780793] RDX: 0000000000000020 RSI: 0000000000000ffe RDI:
>         > 0000000000000000
>         > [   14.780799] RBP: ffff8800717bde68 R08: 0000000000000023 R09:
>         > 0000000000000001
>         > [   14.780806] R10: ffffffff8182d004 R11: 0000000000000000 R12:
>         > 0000000000000000
>         > [   14.780812] R13: 00000002dd253558 R14: 0000000000000ffe R15:
>         > ffff88000b515000
>         > [   14.780822] FS:  00007feac5f86720(0000)
>         GS:ffff880011423000(0000)
>         > knlGS:0000000000000000
>         > [   14.780829] CS:  e033 DS: 0000 ES: 0000 CR0: 000000008005003b
>         > [   14.780834] CR2: 00000002dd253558 CR3: 00000000789db000 CR4:
>         > 0000000000002660
>         > [   14.780841] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
>         > 0000000000000000
>         > [   14.780847] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
>         > 0000000000000400
>         > [   14.780854] Process irqbalance (pid: 880, threadinfo
>         > ffff8800717bc000, task ffff88007306c7e0)
>         > [   14.780861] Stack:
>         > [   14.780864]  ffffffff819180a0 ffff88000b515000
>         ffffffff81944798
>         > ffff88000a861da8
>         > [   14.780874] <0> ffff8800717bdf48 ffff88000aa780a0
>         ffff8800717bde88
>         > ffffffff8135760b
>         > [   14.780885] <0> ffff88000a861da8 fffffffffffffffb
>         ffff8800717bdea8
>         > ffffffff814061ef
>         > [   14.780898] Call Trace:
>         > [   14.780905]  [<ffffffff8135760b>] local_cpus_show+0x4b/0x70
>         > [   14.780913]  [<ffffffff814061ef>] dev_attr_show+0x2f/0x70
>         > [   14.780921]  [<ffffffff811df8ed>] sysfs_read_file+0x10d/0x1f0
>         > [   14.781108]  [<ffffffff8116d018>] vfs_read+0xc8/0x1a0
>         > [   14.781114]  [<ffffffff8116d1f5>] sys_read+0x55/0x90
>         > [   14.781123]  [<ffffffff810151f2>]
>         system_call_fastpath+0x16/0x1b
>         > [   14.781129] Code: 45 31 e4 83 e1 e0 89 cb 83 eb 20 78 62
>         66 90 89
>         > d8 89 d9 41 b9 01 00 00 00 c1 f8 06 83 e1 3f 44 8d 42 03 48
>         98 49 63
>         > fc 44 89 f6 <49> 8b 44 c5 00 49 8d 3c 3f 44 29 e6 41 c1 f8
>         02 48 d3 e8
>         > 89 d1
>         > [   14.781206] RIP  [<ffffffff8134019c>]
>         bitmap_scnprintf+0x5c/0xc0
>         > [   14.781213]  RSP <ffff8800717bde38>
>         > [   14.781217] CR2: 00000002dd253558
>         > [   14.781224] ---[ end trace ec14b09e94a4d7d5 ]---
>         >
>         > The system appears stable after this, although no additional
>         testing
>         > has been done - this is a fresh conversion from hvm to pvops
>         and has
>         > zero mileage on it.
>         >
>         > dom0/domU config is attached - it's a slightly modified
>         version of
>         > Pasi's recommended configs.
>
>         How many cpus do you have configured and online?
>
>            J
>
>
> I re-ran the same test with 1 cpu/vcpu and the BUG was _not_ present.
>
> Incrementing cpus and vcpus to 2 did cause the problem.
>
> If there anything else I can do to provide more information that would
> assist in troubleshooting, just ask.

I haven't had a chance to look at this, but something odd must be going
on; irqbalanced works OK for me (though I don't generally recommend
using it).  Do you think you could try and work out what irqbalanced is
doing to trigger the problem (ie, what string it is writing into what file)?

Thanks,
    J