From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 28 Jan 2008 10:51:03 -0800 (PST) From: Christoph Lameter Subject: Re: [patch 1/4] mmu_notifier: Core code In-Reply-To: <20080126115639.GQ26420@sgi.com> Message-ID: References: <20080125055606.102986685@sgi.com> <20080125055801.212744875@sgi.com> <20080125183934.GO26420@sgi.com> <20080125185646.GQ3058@sgi.com> <20080125193554.GP26420@sgi.com> <20080126115639.GQ26420@sgi.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Robin Holt Cc: Andrea Arcangeli , Avi Kivity , Izik Eidus , Nick Piggin , kvm-devel@lists.sourceforge.net, Benjamin Herrenschmidt , Peter Zijlstra , steiner@sgi.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, daniel.blueman@quadrics.com, Hugh Dickins List-ID: On Sat, 26 Jan 2008, Robin Holt wrote: > > No you cannot do that because there are still callbacks that come later. > > The invalidate_all may lead to invalidate_range() doing nothing for this > > mm. The ops notifier and the freeing of the structure has to wait until > > release(). > > Could you be a little more clear here? If you are saying that the other > callbacks will need to do work? I can assure you we will clean up those > pages and raise memory protections. It will also be done in a much more > efficient fashion than the individual callouts. No the other callbacks need to work in the sense that they can be called. You could have them do nothing after an invalidate_all(). But you cannot release the allocated structs needed for list traversal etc. > If, on the other hand, you are saying we can not because of the way > we traverse the list, can we return a result indicating to the caller > we would like to be unregistered and then the mmu_notifier code do the > remove followed by a call to the release notifier? You would need to release the resources when the release notifier is called. > > That does not sync with the current scheme of the invalidate_range() > > hooks. We would have to do a global invalidate early and then place the > > other invalidate_range hooks in such a way that none is called in later in > > process exit handling. > > But if the notifier is removed from the list following the invalidate_all > callout, there would be no additional callouts. Hmmm.... Okay did not think about that. Then you would need to do a synchronize_rcu() in invalidate_all()? -- 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