From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] KVM: MMU: Fix rmap_remove() race Date: Thu, 27 Mar 2008 16:35:55 +0200 Message-ID: <47EBB0CB.8020703@qumranet.com> References: <1206543773-26386-1-git-send-email-avi@qumranet.com> <20080326192231.GC11130@v2.random> <20080326192746.GD11130@v2.random> <47EB56BE.9000909@qumranet.com> <20080327135256.GB13959@duo.random> <47EBA7A8.2020804@qumranet.com> <20080327142633.GC13959@duo.random> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel@lists.sourceforge.net, Marcelo Tosatti To: Andrea Arcangeli Return-path: In-Reply-To: <20080327142633.GC13959@duo.random> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces@lists.sourceforge.net Errors-To: kvm-devel-bounces@lists.sourceforge.net List-Id: kvm.vger.kernel.org Andrea Arcangeli wrote: > On Thu, Mar 27, 2008 at 03:56:56PM +0200, Avi Kivity wrote: > >> That's not good. We need to support the older userspace, for a while yet. >> >> Why is there a problem? IIRC it's just anonymous memory. >> > > Problem is that for it to be unmapped __do_fault must call > page_add_new_anon_rmap on it. Even anon would be 1, that would mean > cow and that's clearly not what you want as it would lose the > visibility on the future guest writes. anon will be 0 if qemu is > reading for example, leaving pinned anonymous memory that mmu > notifiers won't be able to swap anymore. This is about providing the > guarantee to the admin, that if he enables the mmu notifiers in the > kernel, giving access to /dev/kvm won't give full mlock privileges > too. Not sure if anybody will care, but it's a bit like removing the > limit on tmpfs that only half ram can be pinned. > We can put it under a Kconfig option. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace