Re: [Xen-devel] Kernel aio bug in Debian 2.6.32-5-xen kernel?

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2012-04-26 at 11:52 +0100, George Dunlap wrote:
> Recently I pulled in new changesets from xen- and qemu-unstable, and
> when creating a PV guest I'm getting errors like the stack trace
> below.  Is this likely to be caused by QEMU using AIO?  It this a bug
> in Xen or in the Debian kernel?  Is there an easy way to turn off aio
> using a config file so I can see if it is qemu's aio?
> 
> The config file is attached, for reference.

Which revision of the Debian kernel is this?

It looks like Squeeze, which was a fairly old snapshot of Jeremy's
Xen.git -- it's certainly not impossible that there were latent AIO bugs
in there and Stefano has been fixing these sort of things in recent
kernels too. So it's very possible we need to backport some fix.

Ian.

> 
>  -George
> 
> [  408.127439] BUG: unable to handle kernel paging request at af00003e
> [  408.133612] IP: [<c10941f8>] set_page_dirty+0x1e/0x4a
> [  408.138726] *pdpt = 0000000033232027 *pde = 0000000000000000
> [  408.144532] Oops: 0000 [#1] SMP
> [  408.147825] last sysfs file: /sys/devices/vif-1-0/uevent
> [  408.153200] Modules linked in: xt_physdev iptable_filter ip_tables
> x_tables xen_evtchn xenfs bridge stp loop snd_p]
> [  408.194797]
> [  408.196359] Pid: 1942, comm: qemu-system-i38 Not tainted
> (2.6.32-5-xen-686 #1) PowerEdge R710
> [  408.204938] EIP: 0061:[<c10941f8>] EFLAGS: 00010286 CPU: 0
> [  408.210485] EIP is at set_page_dirty+0x1e/0x4a
> [  408.214991] EAX: af000006 EBX: 00000000 ECX: c4ad7680 EDX: 41000001
> [  408.221317] ESI: c4ad7680 EDI: f4f0c54c EBP: f3353200 ESP: f33bfdb8
> [  408.227644]  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0069
> [  408.233104] Process qemu-system-i38 (pid: 1942, ti=f33be000
> task=f3de50c0 task.ti=f33be000)
> [  408.241508] Stack:
> [  408.243588]  c10944f0 00000000 f4f0c500 c10d991a f33533c8 f3353200
> f4f0c500 c10dc048
> [  408.251128] <0> 00000001 00001000 00000000 c10dcc44 00000001
> c1006767 00000000 00000000
> [  408.259189] <0> d4646070 00000000 f2f0869c f3ff4900 00000000
> 0000000c 00001000 00000000
> [  408.267509] Call Trace:
> [  408.270025]  [<c10944f0>] ? set_page_dirty_lock+0x22/0x30
> [  408.275486]  [<c10d991a>] ? bio_set_pages_dirty+0x22/0x2f
> [  408.280944]  [<c10dc048>] ? dio_bio_submit+0x3c/0x57
> [  408.285970]  [<c10dcc44>] ? __blockdev_direct_IO+0x903/0xaed
> [  408.291691]  [<c1006767>] ? xen_restore_fl_direct_end+0x0/0x1
> [  408.297500]  [<f62a2494>] ? ext3_direct_IO+0xed/0x18d [ext3]
> [  408.303219]  [<f62a2e2b>] ? ext3_get_block+0x0/0xd1 [ext3]
> [  408.308764]  [<c1090687>] ? generic_file_aio_read+0xf9/0x57b
> [  408.314483]  [<c1006040>] ? xen_force_evtchn_callback+0xc/0x10
> [  408.320376]  [<c1006770>] ? check_events+0x8/0xc
> [  408.325056]  [<c1006040>] ? xen_force_evtchn_callback+0xc/0x10
> [  408.330949]  [<c109058e>] ? generic_file_aio_read+0x0/0x57b
> [  408.336584]  [<c10e3725>] ? aio_rw_vect_retry+0x61/0x122
> [  408.341955]  [<c10e45fa>] ? aio_run_iocb+0x61/0xef
> [  408.346809]  [<c10e4ec9>] ? sys_io_submit+0x409/0x49c
> [  408.351923]  [<c1008f9c>] ? syscall_call+0x7/0xb
> [  408.356600] Code: c3 f6 00 10 75 04 f0 80 08 10 31 c0 c3 89 c1 8b
> 40 10 8b 11 f7 c2 00 00 01 00 74 07 b8 ec 71 3d
> [  408.375492] EIP: [<c10941f8>] set_page_dirty+0x1e/0x4a SS:ESP 0069:f33bfdb8
> [  408.382512] CR2: 00000000af00003e
> [  408.385894] ---[ end trace 9ce48eb2f06897bf ]---



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