Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030285AbVKCPLY (ORCPT ); Thu, 3 Nov 2005 10:11:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030266AbVKCPLY (ORCPT ); Thu, 3 Nov 2005 10:11:24 -0500 Received: from [194.90.237.34] ([194.90.237.34]:13014 "EHLO mtlex01.yok.mtl.com") by vger.kernel.org with ESMTP id S1030285AbVKCPLX (ORCPT ); Thu, 3 Nov 2005 10:11:23 -0500 Date: Thu, 3 Nov 2005 17:14:21 +0200 From: "Michael S. Tsirkin" To: Hugh Dickins Cc: Gleb Natapov , Benjamin Herrenschmidt , Petr Vandrovec , Nick Piggin , Badari Pulavarty , Linux Kernel Mailing List Subject: Re: Nick's core remove PageReserved broke vmware... Message-ID: <20051103151421.GD31134@mellanox.co.il> Reply-To: "Michael S. Tsirkin" References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1628 Lines: 37 Quoting Hugh Dickins : > > All existing drivers that set VM_DONTCOPY also set VM_IO. > > So lets just disable playing with these flags from madvise if VM_IO is set. > > There's no reason I can see that the driver should have a say > > on what the process does with its own (non-IO) memory. > > Sounds good? > > You're then saying that a process cannot set VM_DONTCOPY on a VM_IO > area to prevent the first child getting the area, but clear it after > so the next child does get a copy of the area. I think it'd be wrong > (surprising) to limit the functionality in that way. Okay, I guess. I am just trying to avoid more VM_ flags. Cant we get rid of the last requirement, then? I dont see why the driver should have a say on what the process does with its own memory. > > By the way, as a separate issue, we still have a problem with DMA to pages > > which are *needed* by the child process. What do you think about VM_COPY > > (to do the old unix thing of actually copying the page instead of > > setting the COW flag) and a matching madvise call to set/clear it? > > I don't much want to add another path into copy_pte_range, actually > copying pages. If the process really wants DMA into such areas, > then it should contain the code for the child to COW them itself? > > Hugh How do you do that, say, for a stack page, or global data section? -- MST - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/