From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755137AbYKDURd (ORCPT ); Tue, 4 Nov 2008 15:17:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752783AbYKDURZ (ORCPT ); Tue, 4 Nov 2008 15:17:25 -0500 Received: from mail-out1.uio.no ([129.240.10.57]:55098 "EHLO mail-out1.uio.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752377AbYKDURY (ORCPT ); Tue, 4 Nov 2008 15:17:24 -0500 Subject: Re: [PATCH] lockd: convert reclaimer thread to kthread interface From: Trond Myklebust To: Jeff Layton Cc: Andrew Morton , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, hch@infradead.org In-Reply-To: <20081104144652.18d2910d@tleilax.poochiereds.net> References: <1225278945-15407-1-git-send-email-jlayton@redhat.com> <20081103131215.75a83236.akpm@linux-foundation.org> <20081103191924.16528bfd@tleilax.poochiereds.net> <1225802508.19864.2.camel@heimdal.trondhjem.org> <20081104134235.0382c873@tleilax.poochiereds.net> <1225826781.30407.11.camel@heimdal.trondhjem.org> <20081104144652.18d2910d@tleilax.poochiereds.net> Content-Type: text/plain Date: Tue, 04 Nov 2008 15:17:14 -0500 Message-Id: <1225829834.30407.38.camel@heimdal.trondhjem.org> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1 Content-Transfer-Encoding: 7bit X-UiO-Spam-info: not spam, SpamAssassin (score=0.0, required=5.0, autolearn=disabled, MISSING_SUBJECT=0.001,NO_RECEIVED=-0.001, uiobl=NO, uiouri=NO) X-UiO-Scanned: 5A92976A16A6BEF05585F086D7F7C2D3F93BF3C8 X-UiO-SPAM-Test: remote_host: 68.40.183.129 spam_score: 0 maxlevel 200 minaction 2 bait 0 mail/h: 1 total 174 max/h 9 blacklist 0 greylist 0 ratelimit 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2008-11-04 at 14:46 -0500, Jeff Layton wrote: > On Tue, 04 Nov 2008 14:26:21 -0500 > Trond Myklebust wrote: > > > On Tue, 2008-11-04 at 13:42 -0500, Jeff Layton wrote: > > > While we're on the subject of signals... > > > > > > Do you have any thoughts/objections to just making the reclaimer thread > > > ignore them altogether? That would simplify the code a bit. > > > > How does the administrator then get out of the situation where the > > server dies (permanently) in the middle of a reclaim? > > > > Erm...Reboot? :) > > Ok, I'm convinced. I suppose that's a good enough argument for > continuing to allow SIGKILL. I guess the only change we need to make to > this patch for now is to remove the "memory leak" comment (unless there > is a leak and I'm just not seeing it). Hold on... I'm not saying that I'm absolutely wedded to the idea of SIGKILL. I'm just stating the reason for allowing it in the first place. All booting NLM servers will have a finite grace period during which lock recovery is allowed, so it is obvious that retrying each RPC call forever is not a good solution. The questions are then "How long do you wait before giving up?" and "What do you do after timing out?". One solution may be to let the administrator set a time-out via a sysctl, and then set a policy for how to deal with the failure. A reasonable set of possible policies may be to either retry recovery at a later time, or to wait for a new reboot notification from the server, or at some point to start sending out SIGLOST to the applications... Cheers Trond