Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760764AbZJJMYc (ORCPT ); Sat, 10 Oct 2009 08:24:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758127AbZJJMYa (ORCPT ); Sat, 10 Oct 2009 08:24:30 -0400 Received: from viefep13-int.chello.at ([62.179.121.33]:49233 "EHLO viefep13-int.chello.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757047AbZJJMYa (ORCPT ); Sat, 10 Oct 2009 08:24:30 -0400 X-SourceIP: 213.93.53.227 Subject: Re: [PATCH 00/31] Swap over NFS -v20 From: Peter Zijlstra To: Pavel Machek Cc: Christoph Hellwig , Suresh Jayaraman , Linus Torvalds , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, Neil Brown , Miklos Szeredi , Wouter Verhelst , trond.myklebust@fys.uio.no In-Reply-To: <20091010120614.GC1811@ucw.cz> References: <1254405858-15651-1-git-send-email-sjayaraman@suse.de> <20091001174201.GA30068@infradead.org> <1254692482.21044.15.camel@laptop> <20091010120614.GC1811@ucw.cz> Content-Type: text/plain Date: Sat, 10 Oct 2009 14:23:41 +0200 Message-Id: <1255177421.11081.0.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.26.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1331 Lines: 32 On Sat, 2009-10-10 at 14:06 +0200, Pavel Machek wrote: > Hi! > > > > One of them > > > would be the whole VM/net work to just make swap over nbd/iscsi safe. > > > > Getting those two 'fixed' is going to be tons of interesting work > > because they involve interaction with userspace daemons. > > > > NBD has fairly simple userspace, but iSCSI has a rather large userspace > > footprint and a rather complicated user/kernel interaction which will be > > mighty interesting to get allocation safe. > > > > Ideally the swap-over-$foo bits have no userspace component. > > > > That said, Wouter is the NBD userspace maintainer and has expressed > > interest into looking at making that work, but its sure going to be > > non-trivial, esp. since exposing PF_MEMALLOC to userspace is a, not over > > my dead-bodym like thing. > > Well, as long as nbd-server is on separate machine (with real swap), > safe swapping over network should be ok, without PF_MEMALLOC for > userspace or similar nightmares, right? Nope, as soon as the nbd-client looses its connection you're up shit creek. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/