From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752536AbZIIIAv (ORCPT ); Wed, 9 Sep 2009 04:00:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752431AbZIIIAu (ORCPT ); Wed, 9 Sep 2009 04:00:50 -0400 Received: from mail-yw0-f173.google.com ([209.85.211.173]:57266 "EHLO mail-yw0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752107AbZIIIAu (ORCPT ); Wed, 9 Sep 2009 04:00:50 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :content-type:content-transfer-encoding; b=nHYKyJNkxhB/d0VIkxnPiG7ypmp1jQTTiGDyD0iP8prlr2+GFhfEcCCku3bOvl6XCc Ry7UKz4+fbq71piULc4uJfFfg5TDOkdwIEqOk7vxOGEoJ2H4S0wHC2yO7mdnvEAsMeBs /lEuLyYYsBQHk//IMYEbtUZmcq8590EquTvdE= Message-ID: <4AA760B6.6070601@gmail.com> Date: Wed, 09 Sep 2009 10:00:54 +0200 From: Jiri Slaby User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; cs-CZ; rv:1.9.1.1) Gecko/20090715 SUSE/3.0b3-8.5 Thunderbird/3.0b3 MIME-Version: 1.0 To: Thomas Gleixner CC: Linux kernel mailing list Subject: clocksource: !keventd_up() && schedule_work() == oops Content-Type: text/plain; charset=ISO-8859-2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, I started to see oopses on boot in qemu machine because keventd is created in kernel_init/do_basic_setup, but schedule_work is done earlier in kernel_init/smp_init[1] when the tsc is unstable during this early phase. It looks like "clocksource: Resolve cpu hotplug dead lock with TSC unstable" is the culprit. Creating its own either singlethread or "multithread" workqueue won't work either (we do not have singlethread_cpu and cpu_populated_map). Checking !keventd_up() in the clocksource code looks to me like a hack. Any ideas, please? [1] kernel_init/smp_init/cpu_up/native_cpu_up/check_tsc_sync_source/mark_tsc_unstable/clocksource_mark_unstable/__clocksource_unstable