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

[Junxiao Bi]

Hi Mark,

On 12/15/2015 03:18 AM, Mark Fasheh wrote:
> On Mon, Dec 14, 2015 at 02:03:17PM +0800, Junxiao Bi wrote:
>>> 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.
> 
> In what sense? The DLM might but the FS should never be making use of such a
> mechanism (it would be for userspace users).
See commit 743b5f1434f5 ("ocfs2: take inode lock in
ocfs2_iop_set/get_acl()"), it used recursive locking and caused a
deadlock, the call trace is in this patch's log.
> 
> We really can't add recursive locks without this getting rejected upstream.
> There's a whole slew of reasons why we don't like those in the kernel.
Is there any harm to support this lock in kernel?

Thanks,
Junxiao.

> 	--Mark
> 
> --
> Mark Fasheh
>