From: Trond Myklebust <trond.myklebust@fys.uio.no>
Subject: Re: [PATCH] [RESEND] Improve idmap parallelism
Date: Mon, 12 Mar 2007 22:17:15 -0400
Message-ID: <1173752235.6428.5.camel@heimdal.trondhjem.org>
References: <1173723596.19257.12.camel@dyn9047022153>
	<1173726535.6436.58.camel@heimdal.trondhjem.org>
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Cc: NFS List <nfs@lists.sourceforge.net>
To: Frank Filz <ffilzlnx@us.ibm.com>
In-Reply-To: <1173726535.6436.58.camel@heimdal.trondhjem.org>
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On Mon, 2007-03-12 at 15:08 -0400, Trond Myklebust wrote:
> On Mon, 2007-03-12 at 11:19 -0700, Frank Filz wrote:
> > Resend: I sent this awhile ago, but it may have been missed with the excitement of Connectathon, weddings, and honeymoons. I've verified it compiles against 2.6.21 (I originally tested it on 2.6.20).
> 
> You forgot the Linux Storage and Filesystem Workshop and FAST. It has
> been an exciting life in the past 2 months. :-)
> 
> At first glance it looks OK. I'll take it for a spin...

Hmm... Apart from having been mangled by your mailer, I immediately
started getting major complaints about scheduling under a spin lock.

Looking more closely, it seems you are holding the read lock while
calling rpc_queue_upcall(), which again will result in a call to
idmap_pipe_upcall(). That won't work since copy_to_user() is allowed to
sleep.

In addition, there were several leakages of the read lock.

Cheers
  Trond


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