Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755316AbZDOGtg (ORCPT ); Wed, 15 Apr 2009 02:49:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751185AbZDOGt0 (ORCPT ); Wed, 15 Apr 2009 02:49:26 -0400 Received: from mga09.intel.com ([134.134.136.24]:6819 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752478AbZDOGt0 (ORCPT ); Wed, 15 Apr 2009 02:49:26 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.40,191,1239001200"; d="scan'208";a="506568541" Subject: Re: 2.6.30-rc2 hangs in get_measured_perf on tigerton From: "Zhang, Yanmin" To: Rusty Russell Cc: LKML , Venkatesh Pallipadi In-Reply-To: <1239775283.2567.846.camel@ymzhang> References: <1239775283.2567.846.camel@ymzhang> Content-Type: text/plain; charset=UTF-8 Date: Wed, 15 Apr 2009 14:49:57 +0800 Message-Id: <1239778197.2567.849.camel@ymzhang> Mime-Version: 1.0 X-Mailer: Evolution 2.22.1 (2.22.1-2.fc9) Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4049 Lines: 94 On Wed, 2009-04-15 at 14:01 +0800, Zhang, Yanmin wrote: > My machine hanged with kernel 2.6.30-rc2 when script read > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor. > > opps happens in get_measured_perf: > > cur.aperf.whole = readin.aperf.whole - > per_cpu(drv_data, cpu)->saved_aperf; > > Because per_cpu(drv_data, cpu)=NULL. > > So function get_measured_perf should check if (per_cpu(drv_data, cpu)==NULL) > and return 0 if it's NULL. > > Other functions have such checking. How about below patch? I tested it on my tigerton machine. --- --- linux-2.6.30-rc2/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c 2009-04-15 02:24:38.000000000 -0400 +++ linux-2.6.30-rc2_cpufreqbug/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c 2009-04-15 02:31:37.000000000 -0400 @@ -277,6 +277,9 @@ static unsigned int get_measured_perf(st unsigned int perf_percent; unsigned int retval; + if (unlikely(per_cpu(drv_data, cpu) == NULL)) + return 0; + if (smp_call_function_single(cpu, read_measured_perf_ctrs, &readin, 1)) return 0; > > yanmin > > > > --------------sys log------------------ > > BUG: unable to handle kernel NULL pointer dereference at 0000000000000020 > IP: [] get_measured_perf+0x4a/0xf9 > PGD a7dd88067 PUD a7ccf5067 PMD 0 > Oops: 0000 [#1] SMP > last sysfs file: /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor > CPU 0 > Modules linked in: video output > Pid: 2091, comm: kondemand/0 Not tainted 2.6.30-rc2 #1 MP Server > RIP: 0010:[] [] get_measured_perf+0x4a/0xf9 > RSP: 0018:ffff880a7d56de20 EFLAGS: 00010246 > RAX: 0000000000000000 RBX: 00000046241a42b6 RCX: ffff88004d219000 > RDX: 000000000000b660 RSI: 0000000000000020 RDI: 0000000000000001 > RBP: ffff880a7f052000 R08: 00000046241a42b6 R09: ffffffff807639f0 > R10: 00000000ffffffea R11: ffffffff802207f4 R12: ffff880a7f052000 > R13: ffff88004d20e460 R14: 0000000000ddd5a6 R15: 0000000000000001 > FS: 0000000000000000(0000) GS:ffff88004d200000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b > CR2: 0000000000000020 CR3: 0000000a7f1bf000 CR4: 00000000000006e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > Process kondemand/0 (pid: 2091, threadinfo ffff880a7d56c000, task ffff880a7d4d18c0) > Stack: > ffff880a7f052078 ffffffff803efd54 00000046241a42b6 000000462ffa9e95 > 0000000000000001 0000000000000001 00000000ffffffea ffffffff8064f41a > 0000000000000012 0000000000000012 ffff880a7f052000 ffffffff80650547 > Call Trace: > [] ? kobject_get+0x12/0x17 > [] ? __cpufreq_driver_getavg+0x42/0x57 > [] ? do_dbs_timer+0x147/0x272 > [] ? do_dbs_timer+0x0/0x272 > [] ? worker_thread+0x15b/0x1f5 > [] ? autoremove_wake_function+0x0/0x2e > [] ? worker_thread+0x0/0x1f5 > [] ? kthread+0x54/0x83 > [] ? child_rip+0xa/0x20 > [] ? kthread+0x0/0x83 > [] ? child_rip+0x0/0x20 > Code: 99 a6 03 00 31 c9 85 c0 0f 85 c3 00 00 00 89 df 4c 8b 44 24 10 48 c7 c2 60 b6 00 00 48 8b 0c fd e0 30 a5 80 4c 89 c3 48 8b 04 0a <48> 2b 58 20 48 8b 44 24 18 48 89 1c 24 48 8b 34 0a 48 2b 46 28 > RIP [] get_measured_perf+0x4a/0xf9 > RSP > CR2: 0000000000000020 > ---[ end trace 2b8fac9a49e19ad4 ]--- > > > -- > 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/ -- 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/