From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 3960A6B0071 for ; Sat, 9 Oct 2010 14:48:35 -0400 (EDT) Message-ID: <4CB0B8EF.3050702@redhat.com> Date: Sat, 09 Oct 2010 20:48:15 +0200 From: Avi Kivity MIME-Version: 1.0 Subject: Re: [PATCH v6 08/12] Handle async PF in a guest. References: <1286207794-16120-1-git-send-email-gleb@redhat.com> <1286207794-16120-9-git-send-email-gleb@redhat.com> <4CADC6C3.3040305@redhat.com> <20101007171418.GA2397@redhat.com> <4CAE00CB.1070400@redhat.com> <20101007180340.GI2397@redhat.com> In-Reply-To: <20101007180340.GI2397@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Gleb Natapov Cc: kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, mingo@elte.hu, a.p.zijlstra@chello.nl, tglx@linutronix.de, hpa@zytor.com, riel@redhat.com, cl@linux-foundation.org, mtosatti@redhat.com List-ID: On 10/07/2010 08:03 PM, Gleb Natapov wrote: > > >> > > >Host side keeps track of outstanding apfs and will not send apf for the > > >same phys address twice. It will halt vcpu instead. > > > > What about different pages, running the scheduler code? > > > We can get couple of nested apfs, just like we can get nested > interrupts. Since scheduler disables preemption second apf will halt. How much is a couple? Consider: SIGSTOP Entire process swapped out SIGCONT We can get APF's on the current code, the scheduler code, the stack, any debugging code in between (e.g. ftrace), and the page tables for all of these. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain. -- 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/ . Don't email: email@kvack.org