Re: NFS lockup after UDP fragments getting lost (was: 8.1 tstile lockup after nfs send error 51)

[Don Lee <MacPPC2%c.icompute.com@localhost>]

If you go back a few years, you can find a thread where I reported tstile lockups on PPC. I don’t remember the details, but it was back in 6.1 as I recall. This is not a new problem, and not limited to NFS. I still have a similar problem with my 7.2 system, usually triggered when I do backups (dump/restore). The dump operation locks up and cannot be killed. The system continues, except any process that trips over the tstile also locks up. Eventually, the system grinds to a complete halt. (can’t even log in) If I catch it before that point, I can almost reboot, but I have to power cycle to kill the tstile process(es), or the reboot also hangs.

-dgl-

> On Jul 31, 2019, at 9:11 AM, Jason Thorpe <thorpej%me.com@localhost> wrote:
> 
> 
>> On Jul 31, 2019, at 1:45 AM, Edgar Fuß <ef%math.uni-bonn.de@localhost> wrote:
>> 
>> NetBSD design error (or so Taylor says) that a vnode lock may be held accross I/O
> 
> 100%
> 
> NetBSD's VFS locking protocol needs a serious overhaul.  At least one other BSD-family VFS (the one in XNU) completely eliminated locking of vnodes at the VFS layer (it's all pushed into the file system back-ends who now have more control over their own locking requirements).  It does have some additional complexities around reference / busy counting and vnode identity, but it works very well in practice.
> 
> I don't know what FreeBSD has done in this area.
> 
> -- thorpej
>