From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrea Arcangeli Subject: [ofa-general] Re: [PATCH 0 of 9] mmu notifier #v12 Date: Wed, 9 Apr 2008 00:06:27 +0200 Message-ID: <20080408220627.GP10133@duo.random> References: <47FBE7C9.9000701@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Nick Piggin , Jack Steiner , Peter Zijlstra , kvm-devel@lists.sourceforge.net, Kanoj Sarcar , Roland Dreier , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Robin Holt , general@lists.openfabrics.org, Hugh Dickins , akpm@linux-foundation.org, Christoph Lameter To: Avi Kivity Return-path: Content-Disposition: inline In-Reply-To: <47FBE7C9.9000701@qumranet.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: general-bounces@lists.openfabrics.org Errors-To: general-bounces@lists.openfabrics.org List-Id: kvm.vger.kernel.org On Wed, Apr 09, 2008 at 12:46:49AM +0300, Avi Kivity wrote: > That's unusual. What happens to the notifier? Suppose I destroy a vm Yes it's quite unusual. > without exiting the process, what happens if it fires? The mmu notifier ops should stop doing stuff (if there will be no memslots they will be noops), or the ops can be replaced atomically with null pointers. The important thing is that the module can't go away until ->release is invoked or until mmu_notifier_unregister returned 0. Previously there was no mmu_notifier_unregister, so adding it can't be a regression compared to #v11, even if it can fail and you may have to retry later after returning to userland. Retrying from userland is always safe in oom kill terms, only looping inside the kernel isn't safe as do_exit has no chance to run.