[dm-devel] Fw: Re: Disk output lockup 2.6.12_rc2 2.6.11.7

[Andrew Morton]

Mikael, have you made any progress on this?

Looks like a device-mapper bug to me.


Begin forwarded message:

Date: Thu, 21 Apr 2005 11:06:10 +0200
From: Mikael Andersson <mikael at karett.se>
To: linux-kernel at vger.kernel.org
Subject: Re: Disk output lockup 2.6.12_rc2 2.6.11.7


Mikael Andersson wrote:
> During heavy io-load a lockup occurs that appears to prevent any disk
> output from taking place. fs is reiserfs on two device-mapper mirrored
> 200G maxtor disks. After the lockup occurs you can to things like 'ls',
> but echo > test.txt will hang.

fs is now ext3

> 
> A typical workload producing the error is doing:
> rsync of large (1GB) over 100Mbit ethernet
> simultaneous compilation / gunzip

Or almost anything that writes something to the disk.

> 
> I've disabled preemption, and tried with and without acpi enabled, with
> and without smp support (it was smp by default so i switched it off).
> Also tried with another nic (rtl8139) since i got an nv_stop_tx:
> TransmitterStatus remained busy<6> in the logs. I also tried 2.6.11.7
> with the same result.

 Tried converting to ext3, some problem, albeit the lockups are less
severe. More of the locked processes can be killed and echo > test.txt
works. So _some_ io gets through.
 The output from sysrq-T is somewhat less confusing though, it appears
then hung processes is somehow being hung in __generic_unplug_device,  i
had a look at the assembler, but couldn't make heads or tails of it. the
code at __generic_unplug_device+19 was test %eax,%eax immediately
preceded by a callq to the test instruction. Obviously something magic
(by my eyes) is going on here.

 Also tried 2.6.12_rc3-mm3

 I'd really like to find a solution to this since it kinda borks the
nice an shiny machine if it can't handle large files without getting
into trouble.

 I've been working on this for two days, have been trying to find
similar bug reports, trying a lot of different kernels and kernel
options to no avail.
 I'm a little out of options right now, any ideas for something to try,
patches to test, or some help in understanding what's happening ?


kmirrord/0 D ffff81003f1bccd8 0 978 9 1731 977 (L-TLB)
Call Trace:
<ffffffff8016a2d6>{cache_alloc_refill+1222}
<ffffffff804a2f9f>{io_schedule+15}
--
kjournald D ffff81003e94bcd8 0 1748 1 2060 953 (L-TLB)
Call Trace:
<ffffffff802e9c13>{__generic_unplug_device+19}
<ffffffff802e9cfd>{generic_unplug_device+189}
--
rsync D 000000701553dccf 0 6903 6901 (NOTLB)
Call Trace:
<ffffffff802e9c13>{__generic_unplug_device+19}
<ffffffff802e9cfd>{generic_unplug_device+189}
--
x86_64-pc-lin D 0000006dc7d23e49 0 13785 13742 (NOTLB)
Call Trace:
<ffffffff802e9cfd>{generic_unplug_device+189}
<ffffffff8040e3ad>{dm_unplug_all+29}

/Mikael Andersson
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