[nfs] process locks in "bo_wwait" on 6.4

[Attilio Rao]

2009/6/29 pluknet <pluknet at gmail.com>:
> 2009/6/29 Attilio Rao <attilio at freebsd.org>:
>> 2009/6/29 pluknet <pluknet at gmail.com>:
>>> 2009/6/29 Attilio Rao <attilio at freebsd.org>:
>>>> 2009/6/29 pluknet <pluknet at gmail.com>:
>>>>> 2009/6/29 Attilio Rao <attilio at freebsd.org>:
>>>>>> 2009/6/29 pluknet <pluknet at gmail.com>:
>>>>>>> 2009/6/26 pluknet <pluknet at gmail.com>:
>>>>>>>> 2009/6/26 pluknet <pluknet at gmail.com>:
>>>>>>>>> Hello.
>>>>>>>>>
>>>>>>>>> While building a module on nfs mounted /usr/src
>>>>>>>>> I got an unkillable process waiting forever in bo_wwait.
>>>>>>>>
>>>>>>>> Small note: iface on NFS server has mtu changed from 1500 to 1450.
>>>>>>>> Can this be a source of the problem?
>>>>>>>
>>>>>>> This is 100% reproducible. Lock in the same place. Any hints?
>>>>>>
>>>>>> Can you also show the value of ps?
>>>>>> A precise map of what processes are doing would give an help.
>>>>>> Also would be useful to printout traces for other threads and not only
>>>>>> the stucked one.
>>>>>>
>>>>>
>>>>> >From another run:
>>>>
>>>> I'm unable to see who would be locking the buffer object in question.
>>>> Do you have INVARIANT_SUPPORT/INVARIANTS on?
>>>
>>> Yes, I do both.
>>>
>>>> What revision of /usr/src/sys/kern/vfs_bio.c are you running with?
>>>>
>>>
>>> As of 6.4-R: CVS rev 1.491.2.12.4.1 / SVN rev 183531.
>>
>> Please try this patch and report.
>>
>> Thanks,
>> Attilio
>>
>> --- src/sys/nfsclient/nfs_vnops.c       2008/02/13 20:44:18     1.281
>> +++ src/sys/nfsclient/nfs_vnops.c       2008/03/22 09:15:15     1.282
>> @@ -33,7 +33,7 @@
>>  */
>>
>>  #include <sys/cdefs.h>
>> -__FBSDID("$FreeBSD:
>> /usr/local/www/cvsroot/FreeBSD/src/sys/nfsclient/nfs_vnops.c,v 1.281
>> 2008/02/13 20:44:18 attilio Exp $");
>> +__FBSDID("$FreeBSD:
>> /usr/local/www/cvsroot/FreeBSD/src/sys/nfsclient/nfs_vnops.c,v 1.282
>> 2008/03/22 09:15:15 jeff Exp $");
>>
>
> Do you refer to the whole svn r177493, or is its nfs part will be enough?
> This only vfs_vnops.c diff seems not applicable without underneath
> kernel part changes.
>
> I'll try. Thanks.

The NFS part should be enough, though I don't understand why it
doesn't trigger a panic on STABLE_6 as long as, at least in my
revision, there is an assert for the buffer object lock to be held in
bufobj_wwait(). What's your sys/kern/vfs_bio.c rev?

Thanks,
Attilio


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