Re: LOR on nfs: vfs_vnops.c:301 kern_descrip.c:1580

From: Kostik Belousov <kostikbel_at_gmail.com>
Date: Tue, 17 Aug 2010 19:04:45 +0300
On Tue, Aug 17, 2010 at 07:42:41PM +0400, pluknet wrote:
> 2010/8/16 Kostik Belousov <kostikbel_at_gmail.com>:
> > On Mon, Aug 16, 2010 at 09:07:24PM +0400, pluknet wrote:
> >> On 16 August 2010 21:05, pluknet <pluknet_at_gmail.com> wrote:
> >> > Hi.
> >> >
> >> > Seeing on mostly idle, recently updated current, while closing a file.
> >> > Presumably never reported on ML.
> [...]
> >>
> > Both LORs are valid. The fork performed deep inside the VFS call stack
> > is obviously problematic. As a workaround, you may fix the number of
> > nfsiods.
> >
> > Proper fix might consist of creating a shepherd thread which only task
> > is to act on the requests on creating new nfsiods.
> >
> > Would you try to implement this ? I will provide the assistance, if needed.
> 
> Hmm.. I tried to move kproc_create() under shepherd thread and now stuck
> with cp process lockup in [bo_wwait] when cp'ing something on nfs: cp a b.
> Did I screw up something?
> See weird draft patch attached (weird, as I have no idea how to nicely
> exchange data between nfs_nfsiodnew() and shep_thread() thread).
Most likely, you loose the requests to create nfsiods since the
existing request in the global variable shep_chan can be overwritten
by new request. You should either sleep till existing request is serviced,
or form a queue.

Also please take a note of the John' suggestion to use the taskqueue.


Received on Tue Aug 17 2010 - 14:04:53 UTC

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