Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751901AbZI1GoZ (ORCPT ); Mon, 28 Sep 2009 02:44:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751524AbZI1GoY (ORCPT ); Mon, 28 Sep 2009 02:44:24 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:42333 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751417AbZI1GoY (ORCPT ); Mon, 28 Sep 2009 02:44:24 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Mon, 28 Sep 2009 15:42:13 +0900 From: KAMEZAWA Hiroyuki To: linux-kernel@vger.kernel.org Cc: "akpm@linux-foundation.org" , mingo@elte.hu, "balbir@linux.vnet.ibm.com" , "nishimura@mxp.nes.nec.co.jp" Subject: Question: RCU stall detected in memcg (Re: mmotm 2009-09-25-14-35 uploaded Message-Id: <20090928154213.8e873dec.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <200909252158.n8PLwFhG024011@imap1.linux-foundation.org> References: <200909252158.n8PLwFhG024011@imap1.linux-foundation.org> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 2.5.0 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4172 Lines: 92 On Fri, 25 Sep 2009 14:35:46 -0700 akpm@linux-foundation.org wrote: > The mm-of-the-moment snapshot 2009-09-25-14-35 has been uploaded to > > http://userweb.kernel.org/~akpm/mmotm/ > > and will soon be available at > > git://git.zen-sources.org/zen/mmotm.git > > It contains the following patches against 2.6.31: > At testing my (small) patch, with high memory pressure to memcg+hierarchy+softlimit, following is shown. == INFO: RCU detected CPU 0 stall (t=10000 jiffies) sending NMI to all CPUs: NMI backtrace for cpu 0 CPU 0: Modules linked in: sco bridge stp bnep l2cap crc16 bluetooth rfkill iptabl e_filter ip_tables ip6table_filter ip6_tables x_tables ipv6 cpufreq_ondemand acpi_cpufreq dm_mirror dm_region_hash dm_log d m_multipath dm_mod uinput ppdev i2c_i801 pcspkr i2c_core bnx2 sg e1000e parport_pc parport button shpchp megaraid_sas sd_mo d scsi_mod ext3 jbd uhci_hcd ohci_hcd ehci_hcd [last unloaded: microcode] Pid: 2886, comm: ruby Not tainted 2.6.31-mm1 #2 PRIMERGY RIP: 0010:[] [] trace_hardirqs_off_ca ller+0x3e/0xb RSP: 0018:ffff88004fa03d98 EFLAGS: 00000006 RAX: 0000000000000046 RBX: 0000000000000c00 RCX: 000000000000e501 RDX: ffff8806133564f0 RSI: 0000000000000002 RDI: ffffffff8102a940 RBP: ffff88004fa03d98 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000002 R13: 0000000000000046 R14: 00000000000000ff R15: ffff88004fa03f48 FS: 00007fdeca0856f0(0000) GS:ffff88004fa00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fdeca09e000 CR3: 0000000619fc6000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: <#DB[1]> <> Pid: 2886, comm: ruby Not tainted 2.6.31-mm1 #2 Call Trace: [] ? show_regs+0x49/0x50 [] nmi_watchdog_tick+0x1e5/0x210 [] do_nmi+0x1b1/0x2e0 [] nmi+0x1a/0x2c [] ? flat_send_IPI_mask+0x90/0xb0 [] ? trace_hardirqs_off_caller+0x3e/0xb0 <> [] trace_hardirqs_off+0xd/0x10 [] flat_send_IPI_mask+0x90/0xb0 [] flat_send_IPI_all+0x69/0x70 [] arch_trigger_all_cpu_backtrace+0x62/0xa0 [] __rcu_pending+0x7e/0x370 [] rcu_check_callbacks+0x47/0x130 [] update_process_times+0x46/0x70 [] tick_sched_timer+0x60/0x160 [] ? tick_sched_timer+0x0/0x160 [] __run_hrtimer+0xba/0x150 [] hrtimer_interrupt+0xd5/0x1b0 [] ? trace_hardirqs_off_thunk+0x3a/0x3c [] smp_apic_timer_interrupt+0x6d/0x9b [] apic_timer_interrupt+0x13/0x20 [] ? mem_cgroup_walk_tree+0x156/0x180 [] ? mem_cgroup_walk_tree+0x73/0x180 [] ? mem_cgroup_walk_tree+0x32/0x180 [] ? mem_cgroup_get_local_stat+0x0/0x110 [] ? mem_control_stat_show+0x14b/0x330 [] ? cgroup_seqfile_show+0x3d/0x60 [] ? cgroup_map_add+0x0/0x30 [] ? seq_read+0xf3/0x420 [] ? security_file_permission+0x16/0x20 [] ? vfs_read+0xcc/0x190 [] ? sys_read+0x55/0x90 [] ? system_call_fastpath+0x16/0x1b ..... == mem_cgroup_walk_tree() is not very young function and I've been doing the same kind of tests but this is 1st messeage for me. So, I'm a bit confused. and not sure how I start debug from... Does this mean mem_cgroup_walk_tree() blocks RCU's progress over 10000 jiffies ? What should I doubt ? Thanks, -Kame -- 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/