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	Mon, 25 Mar 2013 08:01:10 -0400
Date: Mon, 25 Mar 2013 08:01:06 -0400
From: Jeff Layton <jlayton@redhat.com>
To: root <ycnian@gmail.com>
Cc: Trond.Myklebust@netapp.com, linux-nfs@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: nfsv4.1 client refuses to suspend
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On Mon, 25 Mar 2013 17:27:40 +0800
root <ycnian@gmail.com> wrote:

> On Fri, Mar 22, 2013 at 07:40:03AM -0400, Jeff Layton wrote:
> > On Fri, 22 Mar 2013 10:57:21 +0800
> > ycnian@gmail.com wrote:
> > 
> > > nfsv4.1 client suspending fails with such info
> > > 
> > > Freezing of tasks failed after 20.00 seconds (1 tasks refusing to freeze, wq_busy=0):
> > > nfsv4.1-svc     S ffff88007889f2e0     0  3191      2 0x00000080   
> > >  ffff88007b2f3e28 0000000000000046 ffff88007b2f2010 00000000000127c0
> > >  ffff880079b08000 00000000000127c0 ffff88007b2f3fd8 00000000000127c0
> > >  ffff88007b2f3fd8 00000000000127c0 ffffffff81a14410 ffff880079b08000
> > > Call Trace:
> > >  [<ffffffff81441396>] schedule+0x64/0x66
> > >  [<ffffffffa06a6892>] nfs41_callback_svc+0x100/0x129 [nfsv4]
> > >  [<ffffffff8104fdb8>] ? wake_up_bit+0x2a/0x2a
> > >  [<ffffffffa06a6792>] ? nfs_callback_up+0x548/0x548 [nfsv4]
> > >  [<ffffffff8104f7e0>] kthread+0xb5/0xbd
> > >  [<ffffffff8104f72b>] ? kthread_freezable_should_stop+0x65/0x65
> > >  [<ffffffff8144912c>] ret_from_fork+0x7c/0xb0
> > >  [<ffffffff8104f72b>] ? kthread_freezable_should_stop+0x65/0x65
> > > 
> > > I read such threads
> > > [1] nfs/sunrpc: allow freezing of tasks with NFS calls in flight
> > > [2] LOCKDEP: 3.9-rc1: mount.nfs/4272 still has locks held!
> > > and then modify nfs41_callback_svc(). It works on my machine. I don't know
> > > the details of freezing, so I'm not sure if the modification is reasonable.
> > > This is not a formal patch. Thanks.
> > > 
> > > Signed-off-by: Yanchuan Nian <ycnian@gmail.com>
> > > ---
> > >  fs/nfs/callback.c |    2 +-
> > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > > 
> > > diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
> > > index 5088b57..8addb7b 100644
> > > --- a/fs/nfs/callback.c
> > > +++ b/fs/nfs/callback.c
> > > @@ -138,7 +138,7 @@ nfs41_callback_svc(void *vrqstp)
> > >  				error);
> > >  		} else {
> > >  			spin_unlock_bh(&serv->sv_cb_lock);
> > > -			schedule();
> > > +			freezable_schedule();
> > >  		}
> > >  		finish_wait(&serv->sv_cb_waitq, &wq);
> > >  	}
> > 
> > I think it'd be better to have that thread call try_to_freeze()
> > directly instead of doing this. There are some problems with
> > freezable_schedule() that still need to be resolved and I suspect that
> > it will eventually go away entirely.
> > 
> > It's may be sufficient to simply call try_to_freeze() at the top of
> > the loop, but that would need to be tested.
> 
> Thanks, I tried it as follow
> echo 'mem' > /sys/power/state
> and it works ok. No further tests.
> > 

I'm a little unclear on what patch you tested...

I just sent one that I think should fix this though. Would you be able
to test it and let me know if it helps?

Thanks,
-- 
Jeff Layton <jlayton@redhat.com>