From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 22 Apr 2008 18:46:15 +0200 From: Andrea Arcangeli Subject: Re: [PATCH 01 of 12] Core of mmu notifiers Message-ID: <20080422164615.GG24536@duo.random> References: <480DFC8A.8040105@cosmosbay.com> <20080422151529.GE24536@duo.random> <480E0642.6080109@cosmosbay.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <480E0642.6080109@cosmosbay.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Eric Dumazet Cc: Christoph Lameter , Nick Piggin , Jack Steiner , Peter Zijlstra , kvm-devel@lists.sourceforge.net, Kanoj Sarcar , Roland Dreier , Steve Wise , linux-kernel@vger.kernel.org, Avi Kivity , linux-mm@kvack.org, Robin Holt , general@lists.openfabrics.org, Hugh Dickins , akpm@linux-foundation.org, Rusty Russell List-ID: On Tue, Apr 22, 2008 at 05:37:38PM +0200, Eric Dumazet wrote: > I am saying your intent was probably to test > > else if ((unsigned long)*(spinlock_t **)a == > (unsigned long)*(spinlock_t **)b) > return 0; Indeed... > Hum, it's not a micro-optimization, but a bug fix. :) The good thing is that even if this bug would lead to a system crash, it would be still zero risk for everybody that isn't using KVM/GRU actively with mmu notifiers. The important thing is that this patch has zero risk to introduce regressions into the kernel, both when enabled and disabled, it's like a new driver. I'll shortly resend 1/12 and likely 12/12 for theoretical correctness. For now you can go ahead testing with this patch as it'll work fine despite of the bug (if it wasn't the case I would have noticed already ;). -- 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