From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752365AbdHAVHQ (ORCPT ); Tue, 1 Aug 2017 17:07:16 -0400 Received: from mail-wm0-f48.google.com ([74.125.82.48]:36114 "EHLO mail-wm0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751981AbdHAVHO (ORCPT ); Tue, 1 Aug 2017 17:07:14 -0400 Date: Tue, 1 Aug 2017 23:07:09 +0200 From: Daniel Lezcano To: Paul McKenney , john.stultz@linaro.org Cc: LKML Subject: RCU stall when using function_graph Message-ID: <20170801210709.GC1919@mai> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Paul, I have been trying to set the function_graph tracer for ftrace and each time I get a CPU stall. How to reproduce: ----------------- echo function_graph > /sys/kernel/debug/tracing/current_tracer This error appears with v4.13-rc3 and v4.12-rc6. Is it something already reported ? [ ... ] [ 472.934986] INFO: rcu_preempt detected stalls on CPUs/tasks: [ 472.941302] 0-...: (3 GPs behind) idle=d1a/2/0 softirq=2556/2557 fqs=3195 [ 472.948982] (detected by 3, t=6502 jiffies, g=549, c=548, q=10) [ 472.955180] Task dump for CPU 0: [ 472.958513] swapper/0 R running task 0 0 0 0x00000002 [ 550.954786] INFO: rcu_preempt detected stalls on CPUs/tasks: [ 550.960657] 0-...: (3 GPs behind) idle=d1a/2/0 softirq=2556/2557 fqs=12926 [ 550.967897] (detected by 3, t=26007 jiffies, g=549, c=548, q=27) [ 550.974181] Task dump for CPU 0: [ 550.977513] swapper/0 R running task 0 0 0 0x00000002 [ 628.974788] INFO: rcu_preempt detected stalls on CPUs/tasks: [ 628.980659] 0-...: (3 GPs behind) idle=d1a/2/0 softirq=2556/2557 fqs=22666 [ 628.987900] (detected by 3, t=45512 jiffies, g=549, c=548, q=43) [ 628.994184] Task dump for CPU 0: [ 628.997518] swapper/0 R running task 0 0 0 0x00000002 [ 706.994787] INFO: rcu_preempt detected stalls on CPUs/tasks: [ 707.000658] 0-...: (3 GPs behind) idle=d1a/2/0 softirq=2556/2557 fqs=31785 [ 707.007899] (detected by 3, t=65017 jiffies, g=549, c=548, q=74) [ 707.014183] Task dump for CPU 0: [ 707.017516] swapper/0 R running task 0 0 0 0x00000002 [ 707.024902] rcu_preempt kthread starved for 1261 jiffies! g549 c548 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x1 [ 707.034548] rcu_preempt S 0 8 2 0x00000000 [ 726.049583] INFO: task jbd2/mmcblk1p2-:1120 blocked for more than 120 seconds. [ 726.061772] Not tainted 4.13.0-rc3-ktest-linaro-hikey #202 [ 726.074294] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 726.089027] jbd2/mmcblk1p2- D 0 1120 2 0x00000000 [ 726.126737] INFO: task rs:main Q:Reg:2272 blocked for more than 120 seconds. [ 726.140484] Not tainted 4.13.0-rc3-ktest-linaro-hikey #202 [ 726.154515] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 726.170140] rs:main Q:Reg D 0 2272 1 0x00000000 [ 726.205626] [ 726.205626] Showing all locks held in the system: [ 726.272952] [ 726.278194] ============================================= [ 726.278194] [ 785.014779] INFO: rcu_preempt detected stalls on CPUs/tasks: [ 785.020658] 0-...: (3 GPs behind) idle=d1a/2/0 softirq=2556/2557 fqs=41387 [ 785.027905] (detected by 3, t=84524 jiffies, g=549, c=548, q=94) [ 785.034194] Task dump for CPU 0: [ 785.037532] swapper/0 R running task 0 0 0 0x00000002 [ 846.879753] INFO: task jbd2/mmcblk1p2-:1120 blocked for more than 120 seconds. [ 846.892966] Not tainted 4.13.0-rc3-ktest-linaro-hikey #202 [ 846.909597] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 846.926726] jbd2/mmcblk1p2- D 0 1120 2 0x00000000 [ 846.981356] INFO: task rs:main Q:Reg:2272 blocked for more than 120 seconds. [ 847.001593] Not tainted 4.13.0-rc3-ktest-linaro-hikey #202 [ 847.017642] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 847.034135] rs:main Q:Reg D 0 2272 1 0x00000000 [ 847.077209] [ 847.077209] Showing all locks held in the system: [ 847.180736] [ 847.186753] ============================================= [ 847.186753] [ 863.034778] INFO: rcu_preempt detected stalls on CPUs/tasks: [ 863.040660] 0-...: (3 GPs behind) idle=d1a/2/0 softirq=2556/2557 fqs=50881 [ 863.047907] (detected by 4, t=104030 jiffies, g=549, c=548, q=114) [ 863.054373] Task dump for CPU 0: [ 863.057711] swapper/0 R running task 0 0 0 0x00000002 [ 941.054780] INFO: rcu_preempt detected stalls on CPUs/tasks: [ 941.060659] 0-...: (3 GPs behind) idle=d1a/2/0 softirq=2556/2557 fqs=59726 [ 941.067903] (detected by 7, t=123535 jiffies, g=549, c=548, q=303) [ 941.074370] Task dump for CPU 0: [ 941.077708] swapper/0 R running task 0 0 0 0x00000002 [ 967.711682] INFO: task jbd2/mmcblk1p2-:1120 blocked for more than 120 seconds. [ 967.725731] Not tainted 4.13.0-rc3-ktest-linaro-hikey #202 [ 967.743347] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 967.765658] jbd2/mmcblk1p2- D 0 1120 2 0x00000000 [ 967.810595] INFO: task rs:main Q:Reg:2272 blocked for more than 120 seconds. [ 967.825360] Not tainted 4.13.0-rc3-ktest-linaro-hikey #202 [ 967.838595] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 967.854460] rs:main Q:Reg D 0 2272 1 0x00000000 [ 967.897804] [ 967.897804] Showing all locks held in the system: [ 967.997067] [ 968.002570] ============================================= [ ... ] etc ... -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog