kqueue LOR

[Maxim Sobolev]

Kostik Belousov wrote:
> On Fri, Sep 07, 2007 at 11:49:50AM -0700, Maxim Sobolev wrote:
>> Hi,
>>
>> On my 6.2 system I am seeing LOR discussed almost 1 year ago here:
>>
>> http://lists.freebsd.org/pipermail/freebsd-stable/2006-November/031048.html
>> http://lists.freebsd.org/pipermail/freebsd-stable/2006-December/031197.html
>>
>> lock order reversal:
>>  1st 0xc52cb500 kqueue (kqueue) @ kern/kern_event.c:1547
>>  2nd 0xc4e4d80c struct mount mtx (struct mount mtx) @ 
>> ufs/ufs/ufs_vnops.c:138
>>
>> Do you have any plans to commit the suggested fix?
> I suspect that the LOR is bogus. I was never able to get the information
> where the reverse lock order happen. What I asked of the most reporters is
> to apply sys/kern/subr_witness.c rev. 1.222 to RELENG_6 and provide me
> with the LOR report, if any.

What do you mean "bogus"? It happens reliably on my system.

> Note that doing that on RELENG_6_2 makes no sense, most likely you will
> get LORs with cdev mutex, fixed in RELENG_6.

I don't quite understand that.

-Maxim