From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] kvm, async_pf: exit idleness when handling KVM_PV_REASON_PAGE_NOT_PRESENT Date: Mon, 22 Oct 2012 14:22:13 +0200 Message-ID: <50853A75.7060301@redhat.com> References: <1350663115-11373-1-git-send-email-sasha.levin@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: gleb@redhat.com, mtosatti@redhat.com, davej@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, paulmck@linux.vnet.ibm.com To: Sasha Levin Return-path: In-Reply-To: <1350663115-11373-1-git-send-email-sasha.levin@oracle.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 10/19/2012 06:11 PM, Sasha Levin wrote: > KVM_PV_REASON_PAGE_NOT_PRESENT kicks cpu out of idleness, but we haven't > marked that spot as an exit from idleness. > > Not doing so can cause RCU warnings such as: > > [ 732.788386] =============================== > [ 732.789803] [ INFO: suspicious RCU usage. ] > [ 732.790032] 3.7.0-rc1-next-20121019-sasha-00002-g6d8d02d-dirty #63 Tainted: G W > [ 732.790032] ------------------------------- > [ 732.790032] include/linux/rcupdate.h:738 rcu_read_lock() used illegally while idle! > [ 732.790032] > [ 732.790032] other info that might help us debug this: > [ 732.790032] > [ 732.790032] > [ 732.790032] RCU used illegally from idle CPU! > [ 732.790032] rcu_scheduler_active = 1, debug_locks = 1 > [ 732.790032] RCU used illegally from extended quiescent state! > [ 732.790032] 2 locks held by trinity-child31/8252: > [ 732.790032] #0: (&rq->lock){-.-.-.}, at: [] __schedule+0x178/0x8f0 > [ 732.790032] #1: (rcu_read_lock){.+.+..}, at: [] cpuacct_charge+0xe/0x200 > [ 732.790032] > [ 732.790032] stack backtrace: > [ 732.790032] Pid: 8252, comm: trinity-child31 Tainted: G W 3.7.0-rc1-next-20121019-sasha-00002-g6d8d02d-dirty #63 > [ 732.790032] Call Trace: > [ 732.790032] [] lockdep_rcu_suspicious+0x10b/0x120 > [ 732.790032] [] cpuacct_charge+0x90/0x200 > [ 732.790032] [] ? cpuacct_charge+0xe/0x200 > [ 732.790032] [] update_curr+0x1a3/0x270 > [ 732.790032] [] dequeue_entity+0x2a/0x210 > [ 732.790032] [] dequeue_task_fair+0x45/0x130 > [ 732.790032] [] dequeue_task+0x89/0xa0 > [ 732.790032] [] deactivate_task+0x1e/0x20 > [ 732.790032] [] __schedule+0x879/0x8f0 > [ 732.790032] [] ? trace_hardirqs_off+0xd/0x10 > [ 732.790032] [] ? kvm_async_pf_task_wait+0x1d5/0x2b0 > [ 732.790032] [] schedule+0x55/0x60 > [ 732.790032] [] kvm_async_pf_task_wait+0x1f4/0x2b0 > [ 732.790032] [] ? abort_exclusive_wait+0xb0/0xb0 > [ 732.790032] [] ? prepare_to_wait+0x25/0x90 > [ 732.790032] [] do_async_page_fault+0x56/0xa0 > [ 732.790032] [] async_page_fault+0x28/0x30 Thanks, applied to master for 3.7. -- error compiling committee.c: too many arguments to function