From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id BCC556007BA for ; Tue, 5 Jan 2010 03:29:18 -0500 (EST) Subject: Re: [RFC][PATCH 4/8] mm: RCU free vmas From: Peter Zijlstra In-Reply-To: <20100105024336.GQ6748@linux.vnet.ibm.com> References: <20100104182429.833180340@chello.nl> <20100104182813.479668508@chello.nl> <20100105024336.GQ6748@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Date: Tue, 05 Jan 2010 09:28:36 +0100 Message-ID: <1262680116.2400.19.camel@laptop> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: paulmck@linux.vnet.ibm.com Cc: KAMEZAWA Hiroyuki , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "minchan.kim@gmail.com" , cl@linux-foundation.org, "hugh.dickins" , Nick Piggin , Ingo Molnar , Linus Torvalds List-ID: On Mon, 2010-01-04 at 18:43 -0800, Paul E. McKenney wrote: > On Mon, Jan 04, 2010 at 07:24:33PM +0100, Peter Zijlstra wrote: > > TODO: > > - should be SRCU, lack of call_srcu() > > > > In order to allow speculative vma lookups, RCU free the struct > > vm_area_struct. > > > > We use two means of detecting a vma is still valid: > > - firstly, we set RB_CLEAR_NODE once we remove a vma from the tree. > > - secondly, we check the vma sequence number. > > > > These two things combined will guarantee that 1) the vma is still > > present and two, it still covers the same range from when we looked it > > up. > > OK, I think I see what you are up to here. I could get you a very crude > throw-away call_srcu() fairly quickly. I don't yet have a good estimate > of how long it will take me to merge SRCU into the treercu infrastructure, > but am getting there. > > So, which release are you thinking in terms of? I'm not thinking any release yet, its very early and as Linus has pointed out, I seem to have forgotten a rather big piece of the picture :/ So I need to try and fix this glaring hole before we can continue. -- 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