From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 9 Sep 2002 12:13:48 +0100 From: "Stephen C. Tweedie" Subject: Re: [RFC] On paging of kernel VM. Message-ID: <20020909121348.B4855@redhat.com> References: <2653.1031563253@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2653.1031563253@redhat.com>; from dwmw2@infradead.org on Mon, Sep 09, 2002 at 10:20:53AM +0100 Sender: owner-linux-mm@kvack.org Return-Path: To: David Woodhouse Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Stephen Tweedie List-ID: Hi, On Mon, Sep 09, 2002 at 10:20:53AM +0100, David Woodhouse wrote: > I think I'd like to introduce 'real' VMAs into kernel space, so that areas > in the vmalloc range can have 'real' vm_ops and more to the point a real > nopage function. The alternative is a kmap-style mechanism for temporarily mapping pages beyond physical memory on demand. That would avoid the space limits we have on vmalloc etc; there's only a few tens of MB of address space we can use for mmap tricks in kernel space, so persistent maps are seriously constrained if you've got a lot of flash you want to map. And with a kmap interface, your locking problems are much simpler --- you can trap accesses at source and you don't have to go hunting ptes to invalidate. Cheers, Stephen -- 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/