From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 20 Feb 2008 16:34:09 +0100 From: Andrea Arcangeli Subject: Re: [PATCH] mmu notifiers #v6 Message-ID: <20080220153409.GA7128@v2.random> References: <20080219084357.GA22249@wotan.suse.de> <20080219135851.GI7128@v2.random> <20080219231157.GC18912@wotan.suse.de> <20080220010941.GR7128@v2.random> <20080220103942.GU7128@v2.random> <20080220144155.GI11391@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080220144155.GI11391@sgi.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Robin Holt Cc: Nick Piggin , akpm@linux-foundation.org, Avi Kivity , Izik Eidus , kvm-devel@lists.sourceforge.net, Peter Zijlstra , general@lists.openfabrics.org, Steve Wise , Roland Dreier , Kanoj Sarcar , steiner@sgi.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, daniel.blueman@quadrics.com, Christoph Lameter List-ID: On Wed, Feb 20, 2008 at 08:41:55AM -0600, Robin Holt wrote: > On Wed, Feb 20, 2008 at 11:39:42AM +0100, Andrea Arcangeli wrote: > > XPMEM simply can't use RCU for the registration locking if it wants to > > schedule inside the mmu notifier calls. So I guess it's better to add > > Whoa there. In Christoph's patch, we did not use rcu for the list. It > was a simple hlist_head. The list manipulations were done under > down_write(¤t->mm->mmap_sem) and would therefore not be racy. All > the callout locations are already acquiring the mmap_sem at least > readably, so we should be safe. Maybe I missed a race somewhere. You missed quite a few, see when atomic=1 and when mmu_rmap_notifier is invoked for example. -- 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