From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 697596B005A for ; Sat, 10 Oct 2009 08:23:53 -0400 (EDT) Subject: Re: [PATCH 00/31] Swap over NFS -v20 From: Peter Zijlstra 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 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org 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 List-ID: 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org