[xfs-masters] xfs deadlock in stable kernel 3.0.4

[Stefan Priebe - Profihost AG]

Am 21.09.2011 13:42, schrieb Dave Chinner:
> Ok, I got a hang in the random delete phase. Not sure what is wrong
> yet, but inode reclaim is trying to reclaim inodes but failing, and
> the AIL is trying to push items but failing. Hence the tail of the
> log is not being moved forward and new transactions are being
> blocked until log space bcomes available.
OK that matches my findings. It was also mostly in the random delete 
phase. But i've also seen it on creates.

> Given this, just triggering a log force is shoul dget everything
> moving again. Running "echo 2>  /proc/sys/vm/drop_caches" gets inode
> reclaim running in sync mode, which causes pinned inodes to trigger
> a log force. And once I've done this, everything starts running
> again.
Oh man i was thinking about trying this. But then i forgot that idea ;-(

> So, the log force not triggering in the AIL code looks to be the
> problem. That, I simply cannot explain right now - it makes no sense
> but that is what all the stats and trace events point to. I need to
> do more investigation.
Thanks Dave and great that you were able to repeat it.

What helps is to build bonnie++ yourself and just remove the stat tests. 
I've done this too - so bonnie++ runs a lot faster.

Stefan