Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755513Ab2K0OCW (ORCPT ); Tue, 27 Nov 2012 09:02:22 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:45818 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752561Ab2K0OCV (ORCPT ); Tue, 27 Nov 2012 09:02:21 -0500 Message-ID: <50B4C7BD.90807@oracle.com> Date: Tue, 27 Nov 2012 09:01:33 -0500 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121112 Thunderbird/16.0.1 MIME-Version: 1.0 To: Gleb Natapov CC: Li Zhong , linux-next list , LKML , paulmck@linux.vnet.ibm.com, avi@redhat.com, fweisbec@gmail.com Subject: Re: [RFC PATCH] Fix abnormal rcu dynticks_nesting values related to async page fault References: <1353993325.14050.49.camel@ThinkPad-T5421.cn.ibm.com> <20121127130703.GW25516@redhat.com> In-Reply-To: <20121127130703.GW25516@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Source-IP: ucsinet21.oracle.com [156.151.31.93] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 844 Lines: 19 On 11/27/2012 08:07 AM, Gleb Natapov wrote: > Those rcu_irq_enter()/rcu_irq_exit() were introduced by commit > c5e015d4949aa665 "KVM guest: exit idleness when handling > KVM_PV_REASON_PAGE_NOT_PRESENT", but now I am starting to question this > commit. KVM_PV_REASON_PAGE_NOT_PRESENT should not kick cpu out of > idleness. kvm_async_pf_task_wait() checks that cpu is idle and calls > halt if it is. After that commit schedule() may be called between > rcu_irq_enter()/rcu_irq_exit() which is probably illegal. Paul? otoh, calling schedule() apparently kicks cpu out of idleness now. Thanks, Sasha -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/