Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753235AbZKLPqc (ORCPT ); Thu, 12 Nov 2009 10:46:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752832AbZKLPqa (ORCPT ); Thu, 12 Nov 2009 10:46:30 -0500 Received: from relay2.mail.masterhost.ru ([83.222.23.62]:49183 "EHLO relay2.mail.masterhost.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751825AbZKLPqa (ORCPT ); Thu, 12 Nov 2009 10:46:30 -0500 Message-ID: <4AFC2DD7.5090407@mayc.ru> Date: Thu, 12 Nov 2009 18:46:31 +0300 From: "Anton D. Kachalov" User-Agent: Thunderbird 2.0.0.23 (X11/20090817) MIME-Version: 1.0 To: =?ISO-8859-1?Q?Am=E9rico_Wang?= CC: linux-kernel@vger.kernel.org Subject: Re: Reading /dev/mem by dd References: <4AFACC03.7080209@mayc.ru> <20091111162052.GD2448@hack> In-Reply-To: <20091111162052.GD2448@hack> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-SpamTest-Envelope-From: mouse@mayc.ru X-SpamTest-Group-ID: 00000000 X-SpamTest-Info: Profiles 10748 [Nov 12 2009] X-SpamTest-Info: {HEADERS: 7-bit header Content-Type found with 8-bit header Content-Transfer-Encoding} X-SpamTest-Method: none X-SpamTest-Rate: 10 X-SpamTest-Status: Not detected X-SpamTest-Status-Extended: not_detected X-SpamTest-Version: SMTP-Filter Version 3.0.0 [0284], KAS30/Release Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4435 Lines: 96 Am?rico Wang wrote: > On Wed, Nov 11, 2009 at 05:36:51PM +0300, Anton D. Kachalov wrote: > >> Hello everyone! >> >> I've found strange behavior of reading /dev/mem: >> >> for i in 0 1 2; do >> echo $i >> dd if=/dev/mem of=/dev/null skip=$((6+$i)) bs=$((0x20000000)) count=1 >> done >> >> On some systems with Supermicro X8DTU I've got several messages during >> first 512Mb starting from 0xc000_0000: >> >> "BUG: soft lockup - CPU#xx stuck for 61s!" >> >> On other systems with the sameboard I've stuck without any errors at >> last 10Mb before 0x1_0000_0000. Local APIC access? >> > > > What is the full backtrace? And which version of kernel are you > running? > > Ubuntu 2.6.28-16-server and 2.6.31-11-server. Nov 10 17:59:10 localhost kernel: [ 243.749254] BUG: soft lockup - CPU#11 stuck for 61s! [dd:4325] Nov 10 17:59:10 localhost kernel: [ 243.749256] Modules linked in: ip_queue ipt_LOG xt_limit ipt_REJECT nf_conntrack_ipv4 nf_defrag_ipv4 xt_state xt_tcpudp x t_multiport xt_NOTRACK nf_conntrack iptable_raw video output iptable_filter ip_tables x_tables dummy parport_pc lp parport igb dca snd_pcm serio_raw snd_timer snd soundcore snd_page_alloc iTCO_wdt iTCO_vendor_support shpchp pcspkr raid10 raid456 raid6_pq async_xor async_memcpy async_tx xor raid1 raid0 multipath linear fbcon tileblit font bitblit softcursor Nov 10 17:59:10 localhost kernel: [ 243.749282] CPU 11: Nov 10 17:59:10 localhost kernel: [ 243.749284] Modules linked in: ip_queue ipt_LOG xt_limit ipt_REJECT nf_conntrack_ipv4 nf_defrag_ipv4 xt_state xt_tcpudp xt_multiport xt_NOTRACK nf_conntrack iptable_raw video output iptable_filter ip_tables x_tables dummy parport_pc lp parport igb dca snd_pcm serio_raw snd_timer snd soundcore snd_page_alloc iTCO_wdt iTCO_vendor_support shpchp pcspkr raid10 raid456 raid6_pq async_xor async_memcpy async_tx xor raid1 raid0 multipath linear fbcon tileblit font bitblit softcursor Nov 10 17:59:10 localhost kernel: [ 243.749305] Pid: 4325, comm: dd Not tainted 2.6.31-11-server #36ya3 X8DTU Nov 10 17:59:10 localhost kernel: [ 243.749307] RIP: 0010:[] [] r_next+0x5/0x30 Nov 10 17:59:10 localhost kernel: [ 243.749316] RSP: 0018:ffff88012b55fe48 EFLAGS: 00000206 Nov 10 17:59:10 localhost kernel: [ 243.749317] RAX: ffff8800280211e0 RBX: ffff88012b55fe88 RCX: 0000000000000118 Nov 10 17:59:10 localhost kernel: [ 243.749319] RDX: ffff88012b55fe60 RSI: ffff8800280211e0 RDI: 0000000000000000 Nov 10 17:59:10 localhost kernel: [ 243.749320] RBP: ffffffff81012aee R08: 000000000000000e R09: ffffffff81795be0 Nov 10 17:59:10 localhost kernel: [ 243.749322] R10: 8000000000000563 R11: 8000000000000573 R12: ffffffff81516179 Nov 10 17:59:10 localhost kernel: [ 243.749323] R13: ffff88012b55fdf8 R14: ffffffff81078449 R15: ffff88012b55fda8 Nov 10 17:59:10 localhost kernel: [ 243.749325] FS: 00007fb8fe3646e0(0000) GS:ffff880028161000(0000) knlGS:0000000000000000 Nov 10 17:59:10 localhost kernel: [ 243.749327] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b Nov 10 17:59:10 localhost kernel: [ 243.749328] CR2: 00007fb8de930000 CR3: 000000012b4fd000 CR4: 00000000000006a0 Nov 10 17:59:10 localhost kernel: [ 243.749330] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 Nov 10 17:59:10 localhost kernel: [ 243.749331] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Nov 10 17:59:10 localhost kernel: [ 243.749333] Call Trace: Nov 10 17:59:10 localhost kernel: [ 243.749337] [] ? iomem_is_exclusive+0x8a/0xb0 Nov 10 17:59:10 localhost kernel: [ 243.749342] [] ? devmem_is_allowed+0x2c/0x50 Nov 10 17:59:10 localhost kernel: [ 243.749346] [] ? read_mem+0xa8/0x180 Nov 10 17:59:10 localhost kernel: [ 243.749350] [] ? vfs_read+0xc4/0x190 Nov 10 17:59:10 localhost kernel: [ 243.749352] [] ? sys_read+0x50/0x90 Nov 10 17:59:10 localhost kernel: [ 243.749356] [] ? system_call_fastpath+0x16/0x1b Same problem with soft lockup I have on this platform under heavy system load but I can't get backtrace for it... -- 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/