From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rusty Russell Subject: Re: 2.6.30-rc2 hangs in get_measured_perf on tigerton Date: Wed, 15 Apr 2009 20:44:17 +0930 Message-ID: <200904152044.17658.rusty@rustcorp.com.au> References: <1239775283.2567.846.camel@ymzhang> Mime-Version: 1.0 Content-Type: Text/Plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from ozlabs.org ([203.10.76.45]:33490 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751016AbZDOLOU convert rfc822-to-8bit (ORCPT ); Wed, 15 Apr 2009 07:14:20 -0400 In-Reply-To: <1239775283.2567.846.camel@ymzhang> Content-Disposition: inline Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Zhang, Yanmin" Cc: LKML , Venkatesh Pallipadi , Denis Sadykov , cpufreq@vger.kernel.org, linux-acpi@vger.kernel.org On Wed, 15 Apr 2009 03:31:23 pm Zhang, Yanmin wrote: > My machine hanged with kernel 2.6.30-rc2 when script read > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor. >=20 > opps happens in get_measured_perf: >=20 > cur.aperf.whole =3D readin.aperf.whole - > per_cpu(drv_data, cpu)->saved_aperf; >=20 > Because =EF=BB=BFper_cpu(drv_data, cpu)=3DNULL. >=20 > So function get_measured_perf should check if (=EF=BB=BFper_cpu(drv_d= ata, cpu)=3D=3DNULL) > and return 0 if it's NULL. >=20 > Other functions have such checking. Possibly true, but I can't see that get_measured_perf() ever did. Unless there's something subtle with preemption no longer being disable= d inside that function... Cc'd the experts. Thanks, Rusty. >=20 > yanmin >=20 >=20 >=20 > --------------sys log------------------ >=20 > BUG: unable to handle kernel NULL pointer dereference at 000000000000= 0020 > IP: [] get_measured_perf+0x4a/0xf9 > PGD a7dd88067 PUD a7ccf5067 PMD 0=20 > Oops: 0000 [#1] SMP=20 > last sysfs file: /sys/devices/system/cpu/cpu0/cpufreq/scaling_governo= r > CPU 0=20 > Modules linked in: video output > Pid: 2091, comm: kondemand/0 Not tainted 2.6.30-rc2 #1 MP Server > RIP: 0010:[] [] get_measured_per= f+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:000000000= 0000000 > 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 fff= f880a7d4d18c0) > 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=20 > RIP [] get_measured_perf+0x4a/0xf9 > RSP > CR2: 0000000000000020 > ---[ end trace 2b8fac9a49e19ad4 ]--- >=20 >=20 -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html