From patchwork Tue Jul 6 16:24:58 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gleb Natapov X-Patchwork-Id: 110442 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter.kernel.org (8.14.4/8.14.3) with ESMTP id o66GUNCG018060 for ; Tue, 6 Jul 2010 16:32:38 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754862Ab0GFQZa (ORCPT ); Tue, 6 Jul 2010 12:25:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48126 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753550Ab0GFQZ2 (ORCPT ); Tue, 6 Jul 2010 12:25:28 -0400 Received: from int-mx08.intmail.prod.int.phx2.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o66GP4sC029763 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Tue, 6 Jul 2010 12:25:04 -0400 Received: from dhcp-1-237.tlv.redhat.com (dhcp-1-237.tlv.redhat.com [10.35.1.237]) by int-mx08.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o66GP3l1018983; Tue, 6 Jul 2010 12:25:03 -0400 Received: by dhcp-1-237.tlv.redhat.com (Postfix, from userid 13519) id DA1ED134415; Tue, 6 Jul 2010 19:25:00 +0300 (IDT) From: Gleb Natapov To: kvm@vger.kernel.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, avi@redhat.com, mingo@elte.hu, a.p.zijlstra@chello.nl, tglx@linutronix.de, hpa@zytor.com, riel@redhat.com, cl@linux-foundation.org, mtosatti@redhat.com Subject: [PATCH v4 10/12] Handle async PF in non preemptable context Date: Tue, 6 Jul 2010 19:24:58 +0300 Message-Id: <1278433500-29884-11-git-send-email-gleb@redhat.com> In-Reply-To: <1278433500-29884-1-git-send-email-gleb@redhat.com> References: <1278433500-29884-1-git-send-email-gleb@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.21 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.3 (demeter.kernel.org [140.211.167.41]); Tue, 06 Jul 2010 16:32:38 +0000 (UTC) diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index fa9f520..f4d87b3 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -37,6 +37,7 @@ #include #include #include +#include #define MMU_QUEUE_SIZE 1024 @@ -68,6 +69,8 @@ struct kvm_task_sleep_node { wait_queue_head_t wq; u32 token; int cpu; + bool halted; + struct mm_struct *mm; }; static struct kvm_task_sleep_head { @@ -96,6 +99,11 @@ static void apf_task_wait(struct task_struct *tsk, u32 token) struct kvm_task_sleep_head *b = &async_pf_sleepers[key]; struct kvm_task_sleep_node n, *e; DEFINE_WAIT(wait); + int cpu, idle; + + cpu = get_cpu(); + idle = idle_cpu(cpu); + put_cpu(); spin_lock(&b->lock); e = _find_apf_task(b, token); @@ -109,17 +117,31 @@ static void apf_task_wait(struct task_struct *tsk, u32 token) n.token = token; n.cpu = smp_processor_id(); + n.mm = percpu_read(cpu_tlbstate.active_mm); + n.halted = idle || preempt_count() > 1; + atomic_inc(&n.mm->mm_count); init_waitqueue_head(&n.wq); hlist_add_head(&n.link, &b->list); spin_unlock(&b->lock); for (;;) { - prepare_to_wait(&n.wq, &wait, TASK_UNINTERRUPTIBLE); + if (!n.halted) + prepare_to_wait(&n.wq, &wait, TASK_UNINTERRUPTIBLE); if (hlist_unhashed(&n.link)) break; - schedule(); + + if (!n.halted) { + schedule(); + } else { + /* + * We cannot reschedule. So halt. + */ + native_safe_halt(); + local_irq_disable(); + } } - finish_wait(&n.wq, &wait); + if (!n.halted) + finish_wait(&n.wq, &wait); return; } @@ -127,7 +149,12 @@ static void apf_task_wait(struct task_struct *tsk, u32 token) static void apf_task_wake_one(struct kvm_task_sleep_node *n) { hlist_del_init(&n->link); - if (waitqueue_active(&n->wq)) + if (!n->mm) + return; + mmdrop(n->mm); + if (n->halted) + smp_send_reschedule(n->cpu); + else if (waitqueue_active(&n->wq)) wake_up(&n->wq); } @@ -157,6 +184,7 @@ again: } n->token = token; n->cpu = smp_processor_id(); + n->mm = NULL; init_waitqueue_head(&n->wq); hlist_add_head(&n->link, &b->list); } else