From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752645AbZI1JWi (ORCPT ); Mon, 28 Sep 2009 05:22:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751609AbZI1JWi (ORCPT ); Mon, 28 Sep 2009 05:22:38 -0400 Received: from an-out-0708.google.com ([209.85.132.251]:13556 "EHLO an-out-0708.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751302AbZI1JWh convert rfc822-to-8bit (ORCPT ); Mon, 28 Sep 2009 05:22:37 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=dPBfoBNFM05ioiBTgiVHRqIPSBqj8P22mHbITVZ3W9CMqLWJQ5cyGL8xjogA4I/R6W 7WFRmybtiSTmng+IwH+tmgIWMyMBENUaPyRZ0eHzNWFY1cwnmSdZxuzbmeGvS3O/RIiv EWg4W821WeYfIzYLvxBdQgtT3h4F391GvZkpY= MIME-Version: 1.0 In-Reply-To: <20090928154213.8e873dec.kamezawa.hiroyu@jp.fujitsu.com> References: <200909252158.n8PLwFhG024011@imap1.linux-foundation.org> <20090928154213.8e873dec.kamezawa.hiroyu@jp.fujitsu.com> Date: Mon, 28 Sep 2009 14:52:39 +0530 X-Google-Sender-Auth: 74c5384b4e5724ee Message-ID: <661de9470909280222g7fef6a0fq947c8e22cfc0029b@mail.gmail.com> Subject: Re: Question: RCU stall detected in memcg (Re: mmotm 2009-09-25-14-35 uploaded From: Balbir Singh To: KAMEZAWA Hiroyuki Cc: linux-kernel@vger.kernel.org, "akpm@linux-foundation.org" , mingo@elte.hu, "nishimura@mxp.nes.nec.co.jp" Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > 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 ? Could you share your test case so that I can reproduce the problem? My tests seem to work fine so far Balbir Singh