From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752656AbYGYOhz (ORCPT ); Fri, 25 Jul 2008 10:37:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751213AbYGYOhr (ORCPT ); Fri, 25 Jul 2008 10:37:47 -0400 Received: from mtiwmhc13.worldnet.att.net ([204.127.131.117]:62027 "EHLO mtiwmhc13.worldnet.att.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751206AbYGYOhq (ORCPT ); Fri, 25 Jul 2008 10:37:46 -0400 Message-ID: <4889E538.5010007@lwfinger.net> Date: Fri, 25 Jul 2008 09:37:44 -0500 From: Larry Finger User-Agent: Thunderbird 2.0.0.12 (X11/20071114) MIME-Version: 1.0 To: LKML , Andi Kleen Subject: Kernel BUG in 2.6.26-git series Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In the current git pulls from Linus's tree, I get a kernel BUG if CONFIG_SCHED_SMT is defined. It does not always appear, but when it does, it is late in the bootup sequence. Perhaps there is a timing issue. This is an x86_64 system on an HP dv2815nr notebook with and AMD Turion X2 CPU. My distro is openSUSE 11.0. kernel: BUG: unable to handle kernel NULL pointer dereference at 000000000000002 kernel: IP: [] sched_mc_power_savings_store+0x13/0x41 kernel: PGD 0 kernel: Oops: 0000 [1] SMP kernel: CPU 0 kernel: Modules linked in: iptable_filter ip_tables x_tables snd_pcm_oss snd_mixer_oss snd_seq snd_ seq_device af_packet nfs rfkill_input lockd nfs_acl sunrpc cpufreq_conservative cpufreq_userspace cpufreq_powersave powernow _k8 fuse loop dm_mod arc4 ecb crypto_blkcipher b43 rfkill snd_hda_intel mac80211 k8temp cfg80211 led_class input_polldev bat tery sr_mod snd_pcm button ac joydev hwmon snd_timer serio_raw cdrom forcedeth ssb snd soundcore snd_page_alloc sg sd_mod oh ci_hcd ehci_hcd usbcore edd fan thermal processor ext3 mbcache jbd pata_amd ahci libata scsi_mod dock kernel: Pid: 3686, comm: sched-powersave Not tainted 2.6.26-Linus-06879-gfb2e405 #71 kernel: RIP: 0010:[] [] sched_mc_power_savings_store+0x13/0x41 kernel: RSP: 0018:ffff8800b8793ea8 EFLAGS: 00010292 kernel: RAX: ffffffff80231ad9 RBX: 0000000000000002 RCX: ffffffffffffffea kernel: RDX: 0000000000000002 RSI: ffff8800b9aed000 RDI: ffffffff805508d0 kernel: RBP: ffff8800b8793eb8 R08: ffff8800b9aed000 R09: 0000000000000000 kernel: R10: ffffffff8027c836 R11: ffffffff80231ad9 R12: ffff8800bb6dc4b0 kernel: R13: 00000000ffffffed R14: ffffffff80550940 R15: ffffffff80550240 kernel: FS: 00007f9c3dc546f0(0000) GS:ffffffff8057ea00(0000) knlGS:00000000f69426d0 kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b kernel: CR2: 0000000000000002 CR3: 00000000b9fe6000 CR4: 00000000000006e0 kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 kernel: DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 kernel: Process sched-powersave (pid: 3686, threadinfo ffff8800b8792000, task ffff8800b876c9c0) kernel: Stack: 0000000000000000 0000000000000002 ffff8800b8ab4980 ffffffff802dbb84 kernel: ffff880037a15458 ffff8800b8793f50 ffff8800b8ab49a0 ffff8800b8fb3a80 kernel: 0000000000000002 ffff8800b8793f50 00007f9c3dc7c000 00007f9c3df40be0 kernel: Call Trace: kernel: [] sysfs_write_file+0xd5/0x10c kernel: [] ? vfs_write+0xad/0x123 kernel: [] ? sys_write+0x45/0x6e kernel: [] ? system_call_fastpath+0x16/0x1b kernel: kernel: kernel: Code: 27 5c 00 00 31 d2 31 f6 31 ff e8 21 fd ff ff e8 c0 5b 00 00 31 c0 c9 c3 55 48 89 e5 53 48 89 cb 48 c7 c1 ea ff ff ff 48 83 ec 08 <8a> 12 8d 42 d0 3c 01 77 1d 31 c0 80 fa 31 0f 94 c0 89 05 11 19 kernel: RIP [] sched_mc_power_savings_store+0x13/0x41 kernel: RSP kernel: CR2: 0000000000000002 ====================================================================== The specific problem is that the buffer pointer in the call to sched_mc_power_savings_store() is NULL. Due to the intermittent nature of the trigger, I have not been able bisect this problem; however, the only recent change in this code was with: commit 4a0b2b4dbe1335b8b9886ba3dc85a145d5d938ed Author: Andi Kleen Date: Tue Jul 1 18:48:41 2008 +0200 sysdev: Pass the attribute to the low level sysdev show/store function If I forgot any essential details, please let me know. Larry