[Ocfs2-devel] [PATCH] ocfs2: dlm: fix recursive locking deadlock

[Junxiao Bi]

On 12/14/2015 01:39 PM, Gang He wrote:
> Hello Junxiao,
> 
> From the initial description, the second lock_XYZ(PR) should be blocked, since DLM have a fair queue  mechanism, otherwise, it looks to bring a write lock starvation.
Should be blocked? No, that is a deadlock. I don't think this recursive
locking is common, so no need care starvation here.

> Second, this issue can be reproduced in old Linux kernels (e.g. 3.16.7-24)? there should not be any regression issue? 
Maybe just hard to reproduce, ocfs2 supports recursive locking.

> Finally, really do not like nested using lock, can we avoid this.
I didn't see a good reason why this should be avoided. Without this,
developer needs pay more attend to not involve recursive locking,
usually that is very hard before run a full test or a very detailed review.

Thanks,
Junxiao.
> 
> Thanks
> Gang
> 
>