Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756285AbZDOGBA (ORCPT ); Wed, 15 Apr 2009 02:01:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752735AbZDOGAv (ORCPT ); Wed, 15 Apr 2009 02:00:51 -0400 Received: from mga09.intel.com ([134.134.136.24]:60948 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752328AbZDOGAu (ORCPT ); Wed, 15 Apr 2009 02:00:50 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.40,190,1239001200"; d="scan'208";a="506558811" Subject: 2.6.30-rc2 hangs in get_measured_perf on tigerton From: "Zhang, Yanmin" To: Rusty Russell Cc: LKML , Venkatesh Pallipadi Content-Type: text/plain; charset=UTF-8 Date: Wed, 15 Apr 2009 14:01:23 +0800 Message-Id: <1239775283.2567.846.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: 3063 Lines: 70 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. 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/