From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754463Ab2LOHB5 (ORCPT ); Sat, 15 Dec 2012 02:01:57 -0500 Received: from mail-la0-f46.google.com ([209.85.215.46]:41162 "EHLO mail-la0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750795Ab2LOHBy (ORCPT ); Sat, 15 Dec 2012 02:01:54 -0500 Message-ID: <50CC205D.4040106@openvz.org> Date: Sat, 15 Dec 2012 11:01:49 +0400 From: Konstantin Khlebnikov User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.11) Gecko/20121123 Firefox/10.0.11 Iceape/2.7.11 MIME-Version: 1.0 To: "Rafael J. Wysocki" CC: linux-kernel@vger.kernel.org, cpufreq , linux-pm Subject: Re: [PATCH] cpufreq_stats: fix race between stats allocation and first usage References: <20121214105921.5139.502.stgit@zurg> <4367394.4dMqb5NnJH@vostro.rjw.lan> In-Reply-To: <4367394.4dMqb5NnJH@vostro.rjw.lan> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Rafael J. Wysocki wrote: > On Friday, December 14, 2012 02:59:21 PM Konstantin Khlebnikov wrote: >> This patch forces complete struct cpufreq_stats allocation for all cpus before >> registering CPUFREQ_TRANSITION_NOTIFIER notifier, otherwise in some conditions >> cpufreq_stat_notifier_trans() can be called in the middle of stats allocation, >> in this case cpufreq_stats_table already exists, but stat->freq_table is NULL. > > I'll queue it up for submission as v3.8 material. > > Does it need to be marked as -stable material too? It's very old and rare bug. I think you can leave it as is. > > Rafael > > >> Signed-off-by: Konstantin Khlebnikov >> Cc: Rafael J. Wysocki >> Cc: cpufreq >> Cc: linux-pm >> >> --- >> >> <1>[ 363.116198] BUG: unable to handle kernel NULL pointer dereference at (null) >> <1>[ 363.116668] IP: [] cpufreq_stat_notifier_trans+0x64/0xf0 [cpufreq_stats] >> <4>[ 363.116977] PGD 23177e067 PUD 2349c1067 PMD 0 >> <4>[ 363.117151] Oops: 0000 [#1] SMP >> <4>[ 363.117151] last sysfs file: /sys/module/freq_table/initstate >> <4>[ 363.117151] CPU 5 >> <4>[ 363.117151] Modules linked in: cpufreq_stats(+)(U) [a lot] [last unloaded: umc] >> <4>[ 363.117151] >> <4>[ 363.117151] Pid: 1690, comm: kondemand/5 veid: 0 Tainted: P WC --------------- T 2.6.32-279.5.1.el6-042stab061.7-vz #112 042stab061_7 System manufacturer System Product Name/Crosshair IV Formula >> <4>[ 363.117151] RIP: 0010:[] [] cpufreq_stat_notifier_trans+0x64/0xf0 [cpufreq_stats] >> <4>[ 363.117151] RSP: 0018:ffff880234281920 EFLAGS: 00010246 >> <4>[ 363.117151] RAX: 00000000001e12e8 RBX: 0000000000000000 RCX: 00000000002ab980 >> <4>[ 363.117151] RDX: 0000000000000004 RSI: 0000000000000000 RDI: 0000000000000005 >> <4>[ 363.117151] RBP: ffff880234281940 R08: 0000000000000000 R09: 0000000000000000 >> <4>[ 363.117151] R10: 0000000000000000 R11: 2222222222222222 R12: ffff880218ce7400 >> <4>[ 363.117151] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 >> <4>[ 363.117151] FS: 00007f499ffe0700(0000) GS:ffff880031000000(0000) knlGS:0000000000000000 >> <4>[ 363.117151] CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b >> <4>[ 363.117151] CR2: 0000000000000000 CR3: 0000000230af7000 CR4: 00000000000006e0 >> <4>[ 363.117151] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >> <4>[ 363.117151] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 >> <4>[ 363.117151] Process kondemand/5 (pid: 1690, veid: 0, threadinfo ffff880234280000, task ffff8802330c48c0) >> <4>[ 363.117151] Stack: >> <4>[ 363.117151] ffffffff810cf4f3 0000000000000001 00000000ffffffff ffffffffa11a7ac0 >> <4>[ 363.117151] ffff880234281990 ffffffff815454a8 ffff880234281c80 0000000000000000 >> <4>[ 363.117151] ffff880234281a10 ffffffff833be978 ffffffff833be8e0 0000000000000001 >> <4>[ 363.117151] Call Trace: >> <4>[ 363.117151] [] ? is_module_text_address+0x23/0x30 >> <4>[ 363.117151] [] notifier_call_chain+0x58/0xb0 >> <4>[ 363.117151] [] __srcu_notifier_call_chain+0x5d/0x90 >> <4>[ 363.117151] [] srcu_notifier_call_chain+0x16/0x20 >> <4>[ 363.117151] [] cpufreq_notify_transition+0x12a/0x190 >> <4>[ 363.117151] [] powernowk8_target+0x628/0xb30 [powernow_k8] >> <4>[ 363.117151] [] __cpufreq_driver_target+0x8b/0x90 >> <4>[ 363.117151] [] do_dbs_timer+0x3b8/0x3bc [cpufreq_ondemand] >> <4>[ 363.117151] [] ? do_dbs_timer+0x0/0x3bc [cpufreq_ondemand] >> <4>[ 363.117151] [] worker_thread+0x264/0x440 >> <4>[ 363.117151] [] ? worker_thread+0x213/0x440 >> <4>[ 363.117151] [] ? worker_thread+0x0/0x440 >> <4>[ 363.117151] [] ? autoremove_wake_function+0x0/0x40 >> <4>[ 363.117151] [] ? worker_thread+0x0/0x440 >> <4>[ 363.117151] [] kthread+0x96/0xa0 >> <4>[ 363.117151] [] child_rip+0xa/0x20 >> <4>[ 363.117151] [] ? restore_args+0x0/0x30 >> <4>[ 363.117151] [] ? kthread+0x0/0xa0 >> <4>[ 363.117151] [] ? child_rip+0x0/0x20 >> <4>[ 363.117151] Code: 89 f9 48 8b 0c cd 20 53 9c 81 4c 8b 24 08 4d 85 e4 74 d3 8b 4a 08 41 8b 54 24 10 45 8b 6c 24 18 85 d2 74 22 49 8b 74 24 28 31 db<3b> 0e 75 10 eb 1a 66 0f 1f 44 00 00 48 63 c3 3b 0c 86 74 0c 83 >> <1>[ 363.117151] RIP [] cpufreq_stat_notifier_trans+0x64/0xf0 [cpufreq_stats] >> <4>[ 363.117151] RSP >> <4>[ 363.117151] CR2: 0000000000000000 >> --- >> drivers/cpufreq/cpufreq_stats.c | 11 +++++++---- >> 1 file changed, 7 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c >> index e40e508..9d7732b 100644 >> --- a/drivers/cpufreq/cpufreq_stats.c >> +++ b/drivers/cpufreq/cpufreq_stats.c >> @@ -364,18 +364,21 @@ static int __init cpufreq_stats_init(void) >> if (ret) >> return ret; >> >> + register_hotcpu_notifier(&cpufreq_stat_cpu_notifier); >> + for_each_online_cpu(cpu) >> + cpufreq_update_policy(cpu); >> + >> ret = cpufreq_register_notifier(¬ifier_trans_block, >> CPUFREQ_TRANSITION_NOTIFIER); >> if (ret) { >> cpufreq_unregister_notifier(¬ifier_policy_block, >> CPUFREQ_POLICY_NOTIFIER); >> + unregister_hotcpu_notifier(&cpufreq_stat_cpu_notifier); >> + for_each_online_cpu(cpu) >> + cpufreq_stats_free_table(cpu); >> return ret; >> } >> >> - register_hotcpu_notifier(&cpufreq_stat_cpu_notifier); >> - for_each_online_cpu(cpu) { >> - cpufreq_update_policy(cpu); >> - } >> return 0; >> } >> static void __exit cpufreq_stats_exit(void) >>