From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH] KVM: nVMX: Don't return error on nested bitmap memory allocation failure Date: Wed, 29 Apr 2015 15:23:58 +0200 Message-ID: <5540DB6E.4070108@redhat.com> References: <554083D4.8090906@siemens.com> <5540D735.5030103@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, Wincy Van , linux-kernel@vger.kernel.org To: Jan Kiszka , Bandan Das Return-path: In-Reply-To: <5540D735.5030103@siemens.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 29/04/2015 15:05, Jan Kiszka wrote: > > Yeah... I hear you. Ok, let me put it this way - Assume that we can > > defer this allocation up until the point that the nested subsystem is > > actually used i.e L1 tries running a guest and we try to allocate this > > area. If get_free_page() failed in that case, would we still want to > > kill L1 too ? I guess no. > > We could block the hypervisor thread on the allocation, just like it > would block on faults for swapped out pages or new ones that have to be > reclaimed from the page cache first. In that case we should avoid making the allocation GFP_ATOMIC to begin with. If a GFP_KERNEL allocation failed, returning -ENOMEM from KVM_RUN (which practically means killing the guest) would actually be a very real possibility. Paolo