Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756444AbcCWSVM (ORCPT ); Wed, 23 Mar 2016 14:21:12 -0400 Received: from e33.co.us.ibm.com ([32.97.110.151]:34613 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755506AbcCWSVK (ORCPT ); Wed, 23 Mar 2016 14:21:10 -0400 X-IBM-Helo: d03dlp01.boulder.ibm.com X-IBM-MailFrom: paulmck@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org Date: Wed, 23 Mar 2016 11:20:55 -0700 From: "Paul E. McKenney" To: "Chatre, Reinette" Cc: Jacob Pan , Josh Triplett , Ross Green , Mathieu Desnoyers , John Stultz , Thomas Gleixner , Peter Zijlstra , lkml , Ingo Molnar , Lai Jiangshan , "dipankar@in.ibm.com" , Andrew Morton , rostedt , David Howells , Eric Dumazet , Darren Hart , =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , Oleg Nesterov , pranith kumar Subject: Re: rcu_preempt self-detected stall on CPU from 4.5-rc3, since 3.17 Message-ID: <20160323182055.GG4287@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20160226005638.GV3522@linux.vnet.ibm.com> <20160318210011.GA571@cloud> <20160318235641.GH4287@linux.vnet.ibm.com> <20160321092230.75f23fa9@yairi> <20160321172616.GU4287@linux.vnet.ibm.com> <0D818C7A2259ED42912C1E04120FDE26712E27C8@ORSMSX111.amr.corp.intel.com> <20160322174011.GM4287@linux.vnet.ibm.com> <0D818C7A2259ED42912C1E04120FDE26712E3DF3@ORSMSX111.amr.corp.intel.com> <20160322211939.GT4287@linux.vnet.ibm.com> <0D818C7A2259ED42912C1E04120FDE26712E4559@ORSMSX111.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0D818C7A2259ED42912C1E04120FDE26712E4559@ORSMSX111.amr.corp.intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16032318-0009-0000-0000-000016773466 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 19117 Lines: 294 On Wed, Mar 23, 2016 at 05:15:11PM +0000, Chatre, Reinette wrote: > Hi Paul, > > On 2016-03-22, Paul E. McKenney wrote: > > On Tue, Mar 22, 2016 at 09:04:47PM +0000, Chatre, Reinette wrote: > >> On 2016-03-22, Paul E. McKenney wrote: > >>> You set CONFIG_RCU_CPU_STALL_TIMEOUT=60, which matches the 60004 > >>> jiffies above. Is that value due to a distro setting or something? > >>> Mainline uses CONFIG_RCU_CPU_STALL_TIMEOUT=21. > >> > >> Indeed ... this value originated from a Fedora configuration. > > > > OK. Setting it shorter might (or might not) make it reproduce more > > quickly. This can be set at boot time via rcupdate.rcu_cpu_stall_timeout. > > Or at compile time via CONFIG_RCU_CPU_STALL_TIMEOUT. > > I kept the original configuration and seem to be able to reproduce with that. > > > >>> If dumping manually shortly after the stall is at all non-trivial > >>> (for example, if your reproduction time is many minute or hours), > >>> I can supply some patches that automate this. Or you can pick > >>> them up from -rcu: > >> > >> ... could you please point me to the patches you refer to? Or would you like > > me to try with the entire kernel from rcu/dev? > > > > 2dc92e2a86b9 (rcu: Awaken grace-period kthread if too long since FQS) > > c3fd2095d015 (rcu: Dump ftrace buffer when kicking grace-period kthread) > > > > There might be other dependencies, but these are the two that you need. > > I did not look closely at the patches when I applied them and because > of that missed that they need a kernel parameter to be activated. After > leaving the system idle overnight with these patches the stalls occurred > but without the parameter I did not capture the data you need. I will > try again tonight. Below are the traces from last night just in case > they have value to you. I know that feeling! Please boot with the following parameters: rcu_tree.rcu_kick_kthreads ftrace trace_event=sched_waking,sched_wakeup,sched_wake_idle_without_ipi Or was this run with tracing? If so, less than three hours isn't too bad. > [10154.635318] INFO: rcu_preempt detected stalls on CPUs/tasks: > [10154.639218] 1-...: (0 ticks this GP) idle=c4e/0/0 softirq=99936/99936 fqs=0 > [10154.643497] (detected by 0, t=60005 jiffies, g=24190, c=24189, q=79) > [10154.647596] Task dump for CPU 1: > [10154.650818] swapper/1 R running task 0 0 1 0x00200000 > [10154.655052] 00002656bf74de5e ffff8801785cfed0 ffffffff818af34c ffff880100000000 > [10154.659349] 0000000600000003 ffff8801785d0000 ffff880072f0bc00 ffffffff822dcf80 > [10154.663636] ffff8801785cc000 ffff8801785cc000 ffff8801785cfee0 ffffffff818af597 > [10154.667916] Call Trace: > [10154.670845] [] ? cpuidle_enter_state+0xfc/0x310 > [10154.674802] [] ? cpuidle_enter+0x17/0x20 > [10154.678564] [] ? call_cpuidle+0x2a/0x40 > [10154.682295] [] ? cpu_startup_entry+0x28d/0x360 > [10154.686187] [] ? start_secondary+0x114/0x140 > [10154.690040] rcu_preempt kthread starved for 60005 jiffies! g24190 c24189 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x1 Still the same type of failure, which is reassuring. Thanx, Paul > [10154.694944] rcu_preempt S ffff8801785b7d68 0 7 2 0x00000000 > [10154.699062] ffff8801785b7d68 ffff88017dc8cc80 ffff8801785c3b80 ffff8801785abb80 > [10154.703275] ffff8801785b8000 ffff8801785b7da0 ffff88017dc8cc80 ffff88017dc8cc80 > [10154.707481] 0000000000000003 ffff8801785b7d80 ffffffff81ab03df 00000001027e21aa > [10154.711692] Call Trace: > [10154.714548] [] schedule+0x3f/0xa0 > [10154.718075] [] schedule_timeout+0x127/0x270 > [10154.721832] [] ? detach_if_pending+0x120/0x120 > [10154.725659] [] rcu_gp_kthread+0x6d3/0xa40 > [10154.729379] [] ? wake_atomic_t_function+0x70/0x70 > [10154.733235] [] ? force_qs_rnp+0x1b0/0x1b0 > [10154.736854] [] kthread+0xe6/0x100 > [10154.740267] [] ? kthread_worker_fn+0x190/0x190 > [10154.743980] [] ret_from_fork+0x3f/0x70 > [10154.747511] [] ? kthread_worker_fn+0x190/0x190 > [11348.912706] INFO: rcu_preempt detected stalls on CPUs/tasks: > [11348.916346] 2-...: (0 ticks this GP) idle=586/0/0 softirq=133504/133504 fqs=0 > [11348.920407] (detected by 3, t=60002 jiffies, g=26799, c=26798, q=72) > [11348.924244] Task dump for CPU 2: > [11348.927205] swapper/2 R running task 0 0 1 0x00200000 > [11348.931178] 00002adc83427a76 ffff8801785d3ed0 ffffffff818af34c ffff880100000000 > [11348.935217] 0000000600000003 ffff8801785d4000 ffff880177d01e00 ffffffff822dcf80 > [11348.939237] ffff8801785d0000 ffff8801785d0000 ffff8801785d3ee0 ffffffff818af597 > [11348.943252] Call Trace: > [11348.945921] [] ? cpuidle_enter_state+0xfc/0x310 > [11348.949615] [] ? cpuidle_enter+0x17/0x20 > [11348.953115] [] ? call_cpuidle+0x2a/0x40 > [11348.956584] [] ? cpu_startup_entry+0x28d/0x360 > [11348.960215] [] ? start_secondary+0x114/0x140 > [11348.963808] rcu_preempt kthread starved for 60002 jiffies! g26799 c26798 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x1 > [11348.968452] rcu_preempt S ffff8801785b7d68 0 7 2 0x00000000 > [11348.972309] ffff8801785b7d68 ffff88017dd0cc80 ffff8801785c5940 ffff8801785abb80 > [11348.976266] ffff8801785b8000 ffff8801785b7da0 ffff88017dd0cc80 ffff88017dd0cc80 > [11348.980207] 0000000000000003 ffff8801785b7d80 ffffffff81ab03df 0000000102c9d45e > [11348.984142] Call Trace: > [11348.986714] [] schedule+0x3f/0xa0 > [11348.989974] [] schedule_timeout+0x127/0x270 > [11348.993453] [] ? detach_if_pending+0x120/0x120 > [11348.997000] [] rcu_gp_kthread+0x6d3/0xa40 > [11349.000431] [] ? wake_atomic_t_function+0x70/0x70 > [11349.004040] [] ? force_qs_rnp+0x1b0/0x1b0 > [11349.007449] [] kthread+0xe6/0x100 > [11349.010676] [] ? kthread_worker_fn+0x190/0x190 > [11349.014216] [] ret_from_fork+0x3f/0x70 > [11349.017568] [] ? kthread_worker_fn+0x190/0x190 > [11790.539207] INFO: rcu_preempt detected stalls on CPUs/tasks: > [11790.542652] 2-...: (0 ticks this GP) idle=944/0/0 softirq=133668/133668 fqs=0 > [11790.546505] (detected by 3, t=60003 jiffies, g=27589, c=27588, q=72) > [11790.550124] Task dump for CPU 2: > [11790.552871] swapper/2 R running task 0 0 1 0x00200000 > [11790.556678] 00002c8422fed65e ffff8801785d3ed0 ffffffff818af34c ffff880100000000 > [11790.560580] 0000000600000003 ffff8801785d4000 ffff880177d01e00 ffffffff822dcf80 > [11790.564485] ffff8801785d0000 ffff8801785d0000 ffff8801785d3ee0 ffffffff818af597 > [11790.568389] Call Trace: > [11790.570942] [] ? cpuidle_enter_state+0xfc/0x310 > [11790.574525] [] ? cpuidle_enter+0x17/0x20 > [11790.577934] [] ? call_cpuidle+0x2a/0x40 > [11790.581311] [] ? cpu_startup_entry+0x28d/0x360 > [11790.584853] [] ? start_secondary+0x114/0x140 > [11790.588350] rcu_preempt kthread starved for 60003 jiffies! g27589 c27588 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x1 > [11790.592945] rcu_preempt S ffff8801785b7d68 0 7 2 0x00000000 > [11790.596808] ffff8801785b7d68 ffff88017dd0cc80 ffff8801785c5940 ffff8801785abb80 > [11790.600751] ffff8801785b8000 ffff8801785b7da0 ffff88017dd0cc80 ffff88017dd0cc80 > [11790.604688] 0000000000000003 ffff8801785b7d80 ffffffff81ab03df 0000000102e5d253 > [11790.608635] Call Trace: > [11790.611220] [] schedule+0x3f/0xa0 > [11790.614480] [] schedule_timeout+0x127/0x270 > [11790.617971] [] ? detach_if_pending+0x120/0x120 > [11790.621530] [] rcu_gp_kthread+0x6d3/0xa40 > [11790.624972] [] ? wake_atomic_t_function+0x70/0x70 > [11790.628558] [] ? force_qs_rnp+0x1b0/0x1b0 > [11790.631904] [] kthread+0xe6/0x100 > [11790.635043] [] ? kthread_worker_fn+0x190/0x190 > [11790.638485] [] ret_from_fork+0x3f/0x70 > [11790.641745] [] ? kthread_worker_fn+0x190/0x190 > [11820.319166] INFO: rcu_preempt detected stalls on CPUs/tasks: > [11820.322523] 2-...: (0 ticks this GP) idle=9b4/0/0 softirq=133674/133674 fqs=0 > [11820.326301] (detected by 3, t=60002 jiffies, g=27620, c=27619, q=64) > [11820.329856] Task dump for CPU 2: > [11820.332536] swapper/2 R running task 0 0 1 0x00200000 > [11820.336228] 00002ca4dc6b2bb1 ffff8801785d3ed0 ffffffff818af34c ffff880100000000 > [11820.339990] 0000000600000003 ffff8801785d4000 ffff880177d01e00 ffffffff822dcf80 > [11820.343749] ffff8801785d0000 ffff8801785d0000 ffff8801785d3ee0 ffffffff818af597 > [11820.347483] Call Trace: > [11820.349852] [] ? cpuidle_enter_state+0xfc/0x310 > [11820.353250] [] ? cpuidle_enter+0x17/0x20 > [11820.356463] [] ? call_cpuidle+0x2a/0x40 > [11820.359637] [] ? cpu_startup_entry+0x28d/0x360 > [11820.362973] [] ? start_secondary+0x114/0x140 > [11820.366264] rcu_preempt kthread starved for 60002 jiffies! g27620 c27619 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x1 > [11820.370643] rcu_preempt S ffff8801785b7d68 0 7 2 0x00000000 > [11820.374276] ffff8801785b7d68 ffff88017dd0cc80 ffff8801785c5940 ffff8801785abb80 > [11820.378026] ffff8801785b8000 ffff8801785b7da0 ffff88017dd0cc80 ffff88017dd0cc80 > [11820.381775] 0000000000000003 ffff8801785b7d80 ffffffff81ab03df 0000000102e7b58c > [11820.385537] Call Trace: > [11820.387940] [] schedule+0x3f/0xa0 > [11820.391005] [] schedule_timeout+0x127/0x270 > [11820.394286] [] ? detach_if_pending+0x120/0x120 > [11820.397626] [] rcu_gp_kthread+0x6d3/0xa40 > [11820.400853] [] ? wake_atomic_t_function+0x70/0x70 > [11820.404269] [] ? force_qs_rnp+0x1b0/0x1b0 > [11820.407478] [] kthread+0xe6/0x100 > [11820.410493] [] ? kthread_worker_fn+0x190/0x190 > [11820.413824] [] ret_from_fork+0x3f/0x70 > [11820.416966] [] ? kthread_worker_fn+0x190/0x190 > [11903.292474] INFO: rcu_preempt detected stalls on CPUs/tasks: > [11903.295736] 2-...: (0 ticks this GP) idle=bd2/0/0 softirq=133700/133700 fqs=0 > [11903.299427] (detected by 3, t=60003 jiffies, g=27759, c=27758, q=277) > [11903.302921] Task dump for CPU 2: > [11903.305513] swapper/2 R running task 0 0 1 0x00200000 > [11903.309164] 00002cf65a063204 ffff8801785d3ed0 ffffffff818af34c ffff880100000000 > [11903.312931] 0000000600000003 ffff8801785d4000 ffff880177d01e00 ffffffff822dcf80 > [11903.316685] ffff8801785d0000 ffff8801785d0000 ffff8801785d3ee0 ffffffff818af597 > [11903.320426] Call Trace: > [11903.322802] [] ? cpuidle_enter_state+0xfc/0x310 > [11903.326199] [] ? cpuidle_enter+0x17/0x20 > [11903.329416] [] ? call_cpuidle+0x2a/0x40 > [11903.332591] [] ? cpu_startup_entry+0x28d/0x360 > [11903.335931] [] ? start_secondary+0x114/0x140 > [11903.339226] rcu_preempt kthread starved for 60003 jiffies! g27759 c27758 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x1 > [11903.343607] rcu_preempt S ffff8801785b7d68 0 7 2 0x00000000 > [11903.347246] ffff8801785b7d68 ffff88017dd0cc80 ffff8801785c5940 ffff8801785abb80 > [11903.350999] ffff8801785b8000 ffff8801785b7da0 ffff88017dd0cc80 ffff88017dd0cc80 > [11903.354750] 0000000000000003 ffff8801785b7d80 ffffffff81ab03df 0000000102ecf7e4 > [11903.358508] Call Trace: > [11903.360909] [] schedule+0x3f/0xa0 > [11903.363979] [] schedule_timeout+0x127/0x270 > [11903.367259] [] ? detach_if_pending+0x120/0x120 > [11903.370601] [] rcu_gp_kthread+0x6d3/0xa40 > [11903.373829] [] ? wake_atomic_t_function+0x70/0x70 > [11903.377243] [] ? force_qs_rnp+0x1b0/0x1b0 > [11903.380455] [] kthread+0xe6/0x100 > [11903.383473] [] ? kthread_worker_fn+0x190/0x190 > [11903.386804] [] ret_from_fork+0x3f/0x70 > [11903.389942] [] ? kthread_worker_fn+0x190/0x190 > [12101.322638] INFO: rcu_preempt detected stalls on CPUs/tasks: > [12101.325902] 2-...: (19 GPs behind) idle=880/0/0 softirq=133768/133768 fqs=1 > [12101.329542] (detected by 1, t=60004 jiffies, g=28170, c=28169, q=41) > [12101.333009] Task dump for CPU 2: > [12101.335599] swapper/2 R running task 0 0 1 0x00200000 > [12101.339248] 00002db4171b61e1 ffff8801785d3ed0 ffffffff818af34c ffff880100000000 > [12101.343008] 0000000600000003 ffff8801785d4000 ffff880177d01e00 ffffffff822dcf80 > [12101.346763] ffff8801785d0000 ffff8801785d0000 ffff8801785d3ee0 ffffffff818af597 > [12101.350501] Call Trace: > [12101.352868] [] ? cpuidle_enter_state+0xfc/0x310 > [12101.356262] [] ? cpuidle_enter+0x17/0x20 > [12101.359475] [] ? call_cpuidle+0x2a/0x40 > [12101.362645] [] ? cpu_startup_entry+0x28d/0x360 > [12101.365980] [] ? start_secondary+0x114/0x140 > [12101.369270] rcu_preempt kthread starved for 60000 jiffies! g28170 c28169 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x1 > [12101.373646] rcu_preempt S ffff8801785b7d68 0 7 2 0x00000000 > [12101.377281] ffff8801785b7d68 ffff88017dd0cc80 ffff8801785c5940 ffff8801785abb80 > [12101.381030] ffff8801785b8000 ffff8801785b7da0 ffff88017dd0cc80 ffff88017dd0cc80 > [12101.384778] 0000000000000003 ffff8801785b7d80 ffffffff81ab03df 0000000102f98533 > [12101.388532] Call Trace: > [12101.390927] [] schedule+0x3f/0xa0 > [12101.393991] [] schedule_timeout+0x127/0x270 > [12101.397266] [] ? detach_if_pending+0x120/0x120 > [12101.400602] [] rcu_gp_kthread+0x6d3/0xa40 > [12101.403825] [] ? wake_atomic_t_function+0x70/0x70 > [12101.407240] [] ? force_qs_rnp+0x1b0/0x1b0 > [12101.410450] [] kthread+0xe6/0x100 > [12101.413465] [] ? kthread_worker_fn+0x190/0x190 > [12101.416793] [] ret_from_fork+0x3f/0x70 > [12101.419930] [] ? kthread_worker_fn+0x190/0x190 > [12269.411058] INFO: rcu_preempt detected stalls on CPUs/tasks: > [12269.414316] 2-...: (27 GPs behind) idle=daa/0/0 softirq=133902/133902 fqs=1 > [12269.417947] (detected by 0, t=60003 jiffies, g=28504, c=28503, q=347) > [12269.421426] Task dump for CPU 2: > [12269.424012] swapper/2 R running task 0 0 1 0x00200000 > [12269.427656] 00002e58b5f8d033 ffff8801785d3ed0 ffffffff818af34c ffff880100000000 > [12269.431405] 0000000600000003 ffff8801785d4000 ffff880177d01e00 ffffffff822dcf80 > [12269.435153] ffff8801785d0000 ffff8801785d0000 ffff8801785d3ee0 ffffffff818af597 > [12269.438886] Call Trace: > [12269.441252] [] ? cpuidle_enter_state+0xfc/0x310 > [12269.444638] [] ? cpuidle_enter+0x17/0x20 > [12269.447850] [] ? call_cpuidle+0x2a/0x40 > [12269.451014] [] ? cpu_startup_entry+0x28d/0x360 > [12269.454348] [] ? start_secondary+0x114/0x140 > [12269.457634] rcu_preempt kthread starved for 59872 jiffies! g28504 c28503 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x1 > [12269.462008] rcu_preempt S ffff8801785b7d68 0 7 2 0x00000000 > [12269.465636] ffff8801785b7d68 ffff88017dd0cc80 ffff8801785c5940 ffff8801785abb80 > [12269.469380] ffff8801785b8000 ffff8801785b7da0 ffff88017dd0cc80 ffff88017dd0cc80 > [12269.473121] 0000000000000003 ffff8801785b7d80 ffffffff81ab03df 0000000103042d26 > [12269.476868] Call Trace: > [12269.479262] [] schedule+0x3f/0xa0 > [12269.482321] [] schedule_timeout+0x127/0x270 > [12269.485592] [] ? detach_if_pending+0x120/0x120 > [12269.488926] [] rcu_gp_kthread+0x6d3/0xa40 > [12269.492144] [] ? wake_atomic_t_function+0x70/0x70 > [12269.495554] [] ? force_qs_rnp+0x1b0/0x1b0 > [12269.498756] [] kthread+0xe6/0x100 > [12269.501764] [] ? kthread_worker_fn+0x190/0x190 > [12269.505090] [] ret_from_fork+0x3f/0x70 > [12269.508224] [] ? kthread_worker_fn+0x190/0x190 > [12426.587923] INFO: rcu_preempt detected stalls on CPUs/tasks: > [12426.591181] 2-...: (17 GPs behind) idle=15c/0/0 softirq=134033/134034 fqs=1 > [12426.594815] (detected by 0, t=60002 jiffies, g=28804, c=28803, q=396) > [12426.598296] Task dump for CPU 2: > [12426.600881] swapper/2 R running task 0 0 1 0x00200000 > [12426.604528] 00002eed4414d5d4 ffff8801785d3ed0 ffffffff818af34c ffff880100000000 > [12426.608284] 0000000600000003 ffff8801785d4000 ffff880177d01e00 ffffffff822dcf80 > [12426.612030] ffff8801785d0000 ffff8801785d0000 ffff8801785d3ee0 ffffffff818af597 > [12426.615762] Call Trace: > [12426.618131] [] ? cpuidle_enter_state+0xfc/0x310 > [12426.621522] [] ? cpuidle_enter+0x17/0x20 > [12426.624733] [] ? call_cpuidle+0x2a/0x40 > [12426.627903] [] ? cpu_startup_entry+0x28d/0x360 > [12426.631238] [] ? start_secondary+0x114/0x140 > [12426.634527] rcu_preempt kthread starved for 59998 jiffies! g28804 c28803 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x1 > [12426.638900] rcu_preempt S ffff8801785b7d68 0 7 2 0x00000000 > [12426.642535] ffff8801785b7d68 ffff88017dd0cc80 ffff8801785c5940 ffff8801785abb80 > [12426.646285] ffff8801785b8000 ffff8801785b7da0 ffff88017dd0cc80 ffff88017dd0cc80 > [12426.650031] 0000000000000003 ffff8801785b7d80 ffffffff81ab03df 00000001030e230e > [12426.653787] Call Trace: > [12426.656186] [] schedule+0x3f/0xa0 > [12426.659251] [] schedule_timeout+0x127/0x270 > [12426.662528] [] ? detach_if_pending+0x120/0x120 > [12426.665868] [] rcu_gp_kthread+0x6d3/0xa40 > [12426.669091] [] ? wake_atomic_t_function+0x70/0x70 > [12426.672502] [] ? force_qs_rnp+0x1b0/0x1b0 > [12426.675710] [] kthread+0xe6/0x100 > [12426.678724] [] ? kthread_worker_fn+0x190/0x190 > [12426.682052] [] ret_from_fork+0x3f/0x70 > [12426.685188] [] ? kthread_worker_fn+0x190/0x190 > >