From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754073Ab0AUNwe (ORCPT ); Thu, 21 Jan 2010 08:52:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752894Ab0AUNwc (ORCPT ); Thu, 21 Jan 2010 08:52:32 -0500 Received: from hera.kernel.org ([140.211.167.34]:46231 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753972Ab0AUNwb (ORCPT ); Thu, 21 Jan 2010 08:52:31 -0500 Date: Thu, 21 Jan 2010 13:51:53 GMT From: tip-bot for Yong Zhang Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, yong.zhang0@gmail.com, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, tglx@linutronix.de, yong.zhang0@gmail.com, mingo@elte.hu In-Reply-To: <2674af741001102238w7b0ddcadref00d345e2181d11@mail.gmail.com> References: <2674af741001102238w7b0ddcadref00d345e2181d11@mail.gmail.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/urgent] sched: Reassign prev and switch_count when reacquire_kernel_lock() fail Message-ID: Git-Commit-ID: 6d558c3ac9b6508d26fd5cadccce51fc9d726b1c X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Thu, 21 Jan 2010 13:51:53 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 6d558c3ac9b6508d26fd5cadccce51fc9d726b1c Gitweb: http://git.kernel.org/tip/6d558c3ac9b6508d26fd5cadccce51fc9d726b1c Author: Yong Zhang AuthorDate: Mon, 11 Jan 2010 14:21:25 +0800 Committer: Ingo Molnar CommitDate: Thu, 21 Jan 2010 13:39:04 +0100 sched: Reassign prev and switch_count when reacquire_kernel_lock() fail Assume A->B schedule is processing, if B have acquired BKL before and it need reschedule this time. Then on B's context, it will go to need_resched_nonpreemptible for reschedule. But at this time, prev and switch_count are related to A. It's wrong and will lead to incorrect scheduler statistics. Signed-off-by: Yong Zhang Signed-off-by: Peter Zijlstra LKML-Reference: <2674af741001102238w7b0ddcadref00d345e2181d11@mail.gmail.com> Signed-off-by: Ingo Molnar --- kernel/sched.c | 5 ++++- 1 files changed, 4 insertions(+), 1 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index c535cc4..4508fe7 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -5530,8 +5530,11 @@ need_resched_nonpreemptible: post_schedule(rq); - if (unlikely(reacquire_kernel_lock(current) < 0)) + if (unlikely(reacquire_kernel_lock(current) < 0)) { + prev = rq->curr; + switch_count = &prev->nivcsw; goto need_resched_nonpreemptible; + } preempt_enable_no_resched(); if (need_resched())