From: "J. Bruce Fields" <bfields@fieldses.org>
To: Paul Menzel <pmenzel@molgen.mpg.de>
Cc: Brian Foster <bfoster@redhat.com>,
linux-nfs@vger.kernel.org, linux-xfs@vger.kernel.org,
it+linux-nfs@molgen.mpg.de, Christoph Hellwig <hch@lst.de>,
Jeff Layton <jlayton@poochiereds.net>
Subject: Re: Locking problems with Linux 4.9 with NFSD and `fs/iomap.c`
Date: Wed, 10 May 2017 13:23:22 -0400 [thread overview]
Message-ID: <20170510172322.GA8470@fieldses.org> (raw)
In-Reply-To: <90423117-4c49-5f61-2dcf-abf6d77c7ba3@molgen.mpg.de>
On Wed, May 10, 2017 at 11:08:52AM +0200, Paul Menzel wrote:
> On 05/08/17 15:18, Brian Foster wrote:
> >>NFS doesn’t respond to a null call.
> >
> >What exactly is a NULL call?
>
> Sorry for not making that clear for non-NFS people. From *NFS
> Version 3 Protocol Specification* [1]:
>
> >Procedure NULL does not do any work. It is made available to
> >allow server response testing and timing.
NFSD has a fixed number of threads for processing requests, so if one of
them hangs in the filesystem while holding a lock, all of them are
likely to eventually end up waiting for that lock, and there will be
none left even to answer NULL requests. So this is a pretty normal
symptom of a deadlock or similar problem.
--b.
prev parent reply other threads:[~2017-05-10 17:23 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-07 19:09 Locking problems with Linux 4.9 with NFSD and `fs/iomap.c` Paul Menzel
2017-05-08 13:18 ` Brian Foster
2017-05-09 9:05 ` Christoph Hellwig
[not found] ` <7ae18b0d-38e3-9b12-0989-ede68956ad43@molgen.mpg.de>
[not found] ` <358037e8-6784-ebca-9fbb-ec7eef3977d6@molgen.mpg.de>
[not found] ` <20170510171757.GA10534@localhost.localdomain>
2017-06-27 11:59 ` Locking problems with Linux 4.9 and 4.11 " Paul Menzel
2017-06-28 16:41 ` Christoph Hellwig
2017-08-01 17:49 ` Paul Menzel
2017-08-01 22:51 ` Dave Chinner
2017-08-10 14:11 ` Paul Menzel
2017-08-10 14:11 ` Paul Menzel
2017-08-10 19:54 ` AW: " Markus Stockhausen
2017-08-10 19:54 ` Markus Stockhausen
2017-08-11 10:15 ` Christoph Hellwig
2017-08-11 15:14 ` Paul Menzel
2017-05-10 9:08 ` Locking problems with Linux 4.9 " Paul Menzel
2017-05-10 17:23 ` J. Bruce Fields [this message]
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