From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 30 Jan 2008 18:56:38 -0800 (PST) From: Christoph Lameter Subject: Re: [kvm-devel] mmu_notifier: invalidate_range_start with lock=1 In-Reply-To: <20080131023401.GY26420@sgi.com> Message-ID: References: <20080130000039.GA7233@v2.random> <20080130161123.GS26420@sgi.com> <20080130170451.GP7233@v2.random> <20080130173009.GT26420@sgi.com> <20080130182506.GQ7233@v2.random> <20080130235214.GC7185@v2.random> <20080131003434.GE7185@v2.random> <20080131023401.GY26420@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 , Nick Piggin , Peter Zijlstra , linux-mm@kvack.org, Benjamin Herrenschmidt , steiner@sgi.com, linux-kernel@vger.kernel.org, Avi Kivity , kvm-devel@lists.sourceforge.net, daniel.blueman@quadrics.com, Hugh Dickins List-ID: One possible way that XPmem could deal with a call of invalidate_range_start with the lock flag set: Scan through the rmaps you have for ptes. If you find one then elevate the refcount of the corresponding page and mark in the maps that you have done so. Also make them readonly. The increased refcount will prevent the freeing of the page. The page will be unmapped from the process and XPmem will retain the only reference. Then some shepherding process that you have anyways with XPmem can sometime later zap the remote ptes and free the pages. Would leave stale data visible on the remote side for awhile. Would that be okay? This would only be used for truncate that uses the unmap_mapping_range call. So we are not in reclaim or other distress. -- 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