On Tue, 21 Sep 2010 22:02:25 +0100
Tim Small [off-list ref] wrote:

Tim Small wrote:

quoted

http://buttersideup.com/files/md-raid1-lockup-lvm-snapshot/iodeadlock-sysrq-t.txt

... this was soon after the io to md2 stopped - md0 seems fine...

oldshoreham:~# cat /proc/mdstat
Personalities : [raid1]
md2 : active raid1 sda6[0] sdb6[1]
      404600128 blocks [2/2] [UU]
      [>....................]  resync =  0.1% (437056/404600128)
finish=343321.2min speed=19K/sec


... I also tried an older Debian 5.0.x kernel from Mar 2009, which is a
less-patched 2.6.26, and got the same results.  2.6.32 hasn't deadlocked
after 10 minutes (2.6.26 usually does within a minute of boot-up), so
I'll leave it re-syncing overnight...
  

2.6.32 resynced to completion, but if possible I'd really like to get
2.6.26 running on this box, as it uses openvz, and the 2.6.32 openvz
patches are still pretty green, I think.  Is their anything in the
sysrq-t output in that link of any use?  Are there any patches I should
try, or would it be better to start bisecting between 2.6.26 and 2.6.32
(assuming I can reproduce the problem without the load pattern which
openvz is producing - which I probably can).

Cheers,

Tim.

It is odd that 2.6.32 works and 2.6.26 doesn't as I cannot find any change
between the two that could be related.
There were some deadlock issues if a read-error was detected during resync
but I don't think you are getting read errors are you?

A bisect would of course be easier for me, though not particularly easy for
you....

Maybe if you can get me a full sysrq-T list that might help.

NeilBrown