From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takuya Yoshikawa Subject: Re: [PATCH] KVM: fix the handling of dirty bitmaps to avoid overflows Date: Tue, 13 Apr 2010 16:03:52 +0900 Message-ID: <4BC41758.4000008@oss.ntt.co.jp> References: <20100412193535.6c502695.yoshikawa.takuya@oss.ntt.co.jp> <20100412173951.GA5614@amt.cnet> <4BC3C048.5030704@oss.ntt.co.jp> <4BC4142C.8050400@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , kvm@vger.kernel.org, kvm-ia64@vger.kernel.org, kvm-ppc@vger.kernel.org To: Avi Kivity Return-path: Received: from serv2.oss.ntt.co.jp ([222.151.198.100]:50516 "EHLO serv2.oss.ntt.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751247Ab0DMHAc (ORCPT ); Tue, 13 Apr 2010 03:00:32 -0400 In-Reply-To: <4BC4142C.8050400@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: >> >> BTW, just from my curiosity, are there any cases in which we use such >> huge >> number of pages currently? >> >> ALIGN(memslot->npages, BITS_PER_LONG) / 8; >> >> More than G pages need really big memory! >> -- We are assuming some special cases like "short" int size? > > No, int is 32 bits, but memslot->npages is not our under control. > > Note that you don't actually need all those pages to create a large > memory slot. > >> >> If so, we may have to care about a lot of things from now on, because >> common >> functions like __set_bit() don't support such long buffers. > > It's better to limit memory slots to something that can be handled by > everything, then. 2^31 pages is plenty. Return -EINVAL if the slot is > too large. I agree with that, so we make this patch pending to fix like that? -- or should make a new patch based on this patch? > >