From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE8FCC3F2CE for ; Wed, 4 Mar 2020 20:36:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8DE962146E for ; Wed, 4 Mar 2020 20:36:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728512AbgCDUgA (ORCPT ); Wed, 4 Mar 2020 15:36:00 -0500 Received: from hua.moonlit-rail.com ([45.79.167.250]:41370 "EHLO hua.moonlit-rail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728539AbgCDUf7 (ORCPT ); Wed, 4 Mar 2020 15:35:59 -0500 Received: from 209-6-248-230.s2276.c3-0.wrx-ubr1.sbo-wrx.ma.cable.rcncustomer.com ([209.6.248.230] helo=boston.moonlit-rail.com) by hua.moonlit-rail.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1j9akH-0004Fl-Lg; Wed, 04 Mar 2020 15:35:57 -0500 Received: from springdale.moonlit-rail.com ([192.168.71.35]) by boston.moonlit-rail.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.93) (envelope-from ) id 1j9akF-0006RO-Ub; Wed, 04 Mar 2020 15:35:55 -0500 Subject: Re: INFO: rcu detected stall in sys_keyctl To: Dmitry Vyukov Cc: syzbot , David Miller , Herbert Xu , "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" , LKML , syzkaller-bugs , Kate Stewart , Thomas Gleixner , Eric Biggers , allison@lohutok.net References: <000000000000dd909105a002ebe6@google.com> <96b956f4-62cb-83e6-38c2-ca698a862282@moonlit-rail.com> From: Kris Karas Message-ID: <32326cc8-86fb-5527-fcf4-db3c19c4ec38@moonlit-rail.com> Date: Wed, 4 Mar 2020 15:35:55 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org Dmitry Vyukov wrote: > Kris Karas wrote: >> [...] >> rcu: INFO: rcu_sched self-detected stall on CPU >> rcu: 14-....: (20999 ticks this GP) >> idle=216/1/0x4000000000000002 softirq=454/454 fqs=5250 >> (t=21004 jiffies g=-755 q=1327) >> NMI backtrace for cpu 14 >> CPU: 14 PID: 520 Comm: pidof Tainted: G D 5.5.7 #1 >> [...] >> I don't have a reproducer for it, either. It showed up in 5.5.7 (but >> might be from earlier as it reproduces so infrequently). > Hi Kris, > > What follows after this stack? That's the most interesting part. The > part that you showed is common for all stalls and does not mean much, > besides the fact that there is a stall. These can well be very > different stalls in different parts of kernel. Hi Dmitry, Sorry, dummy me, I should have found my original post in Lore and posted a link to that. Oh, here we go: https://lore.kernel.org/lkml/6d4f9ac8-a478-2ae4-0fe3-5d074d267148@moonlit-rail.com/ Given that the stall stack is not terribly useful, it would seem that the OOPS I saw was probably unrelated to this one caught by syzbot, though the stalled CPU does make me curious (as in all the OOPSen I've encountered in the past 25 years have rarely mentioned an RCU stall).  For convenience, I'll re-post everything I was able to salvage from dmesg originally. Kris The OOPS in the dump, below, occurred while the machine was booting, right about the time that /sbin/init switched from runstate S => 3.  System daemons (haveged, named, syslogd, etc...) were starting. The OOPS occurred in /bin/pidof, which is no doubt checking whether a daemon is up before attempting to start it.  Under the OOPS, the filesystem was functioning (at least well enough to save dmesg to a file), though many things were hanging.  It required an Alt-SysRq-E to get me a login prompt, and I lucked out in PAM and friends working well enough to give me a functioning command prompt. Alt-SysRq-S,U,S,B was necessary to reboot.  Without further ado... BUG: kernel NULL pointer dereference, address: 00000000000000e8 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 7f6a50067 P4D 7f6a50067 PUD 7f6a51067 PMD 0 Oops: 0000 [#1] SMP CPU: 3 PID: 516 Comm: pidof Not tainted 5.5.7 #1 Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./X470 Taichi, BIOS P3.50 07/18/2019 RIP: 0010:cap_capable+0x13/0x70 Code: bf f4 ff ff ff 66 90 e9 01 ff ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 4c 8b 87 88 00 00 00 4c 39 c6 74 39 45 8b 88 e8 00 00 00 <44> 39 8e e8 00 00 00 7e 18 48 8b 86 e0 00 00 00 4c 39 c0 74 12 48 RSP: 0018:ffffc90000777cb0 EFLAGS: 00010207 RAX: ffff8887f96ea000 RBX: 0000000000000002 RCX: 0000000000000002 RDX: 0000000000000013 RSI: 0000000000000000 RDI: ffff8887f9646480 RBP: 0000000000000013 R08: ffffffff82423da0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8887f9646480 R14: ffffffff822a7620 R15: ffff8887fae600c0 FS: 00007f8ee26cd740(0000) GS:ffff8887fecc0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000000000e8 CR3: 00000007f8691000 CR4: 00000000003406e0 Call Trace: security_capable+0x36/0x50 ptrace_has_cap+0x14/0x30 __ptrace_may_access+0x76/0x110 ptrace_may_access+0x28/0x50 do_task_stat+0x7b/0xd90 ? do_filp_open+0xab/0x100 proc_single_show+0x54/0xc0 ? __kmalloc+0x183/0x210 seq_read+0xbb/0x3c0 vfs_read+0xc6/0x150 ksys_read+0x6b/0x100 do_syscall_64+0x3d/0x120 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f8ee27d682e Code: c0 e9 f6 fe ff ff 50 48 8d 3d b6 5d 0a 00 e8 e9 fd 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28 RSP: 002b:00007ffdc7fdcf58 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007f8ee28ce958 RCX: 00007f8ee27d682e RDX: 0000000000000400 RSI: 00000000017e2590 RDI: 0000000000000004 RBP: 00007f8ee28ce950 R08: 00007f8ee28ac120 R09: 00007ffdc7fdce00 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004 R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffdc7fddf02 Modules linked in: CR2: 00000000000000e8 ---[ end trace 9da0e81512fbb929 ]--- RIP: 0010:cap_capable+0x13/0x70 Code: bf f4 ff ff ff 66 90 e9 01 ff ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 4c 8b 87 88 00 00 00 4c 39 c6 74 39 45 8b 88 e8 00 00 00 <44> 39 8e e8 00 00 00 7e 18 48 8b 86 e0 00 00 00 4c 39 c0 74 12 48 RSP: 0018:ffffc90000777cb0 EFLAGS: 00010207 RAX: ffff8887f96ea000 RBX: 0000000000000002 RCX: 0000000000000002 RDX: 0000000000000013 RSI: 0000000000000000 RDI: ffff8887f9646480 RBP: 0000000000000013 R08: ffffffff82423da0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8887f9646480 R14: ffffffff822a7620 R15: ffff8887fae600c0 FS: 00007f8ee26cd740(0000) GS:ffff8887fecc0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000000000e8 CR3: 00000007f8691000 CR4: 00000000003406e0 udevd[518]: starting eudev-3.2.9 rcu: INFO: rcu_sched self-detected stall on CPU rcu: 14-....: (20999 ticks this GP) idle=216/1/0x4000000000000002 softirq=454/454 fqs=5250 (t=21004 jiffies g=-755 q=1327) NMI backtrace for cpu 14 CPU: 14 PID: 520 Comm: pidof Tainted: G D 5.5.7 #1 Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./X470 Taichi, BIOS P3.50 07/18/2019 Call Trace: dump_stack+0x50/0x70 nmi_cpu_backtrace.cold+0x14/0x53 ? lapic_can_unplug_cpu.cold+0x44/0x44 nmi_trigger_cpumask_backtrace+0x7b/0x88 rcu_dump_cpu_stacks+0x7b/0xa9 rcu_sched_clock_irq.cold+0x152/0x39b update_process_times+0x1f/0x50 tick_sched_timer+0x40/0x90 ? tick_sched_do_timer+0x50/0x50 __hrtimer_run_queues+0xdd/0x180 hrtimer_interrupt+0x108/0x230 smp_apic_timer_interrupt+0x53/0xa0 apic_timer_interrupt+0xf/0x20 RIP: 0010:queued_spin_lock_slowpath+0x41/0x1a0 Code: 2f 08 0f 92 c0 0f b6 c0 c1 e0 08 89 c2 8b 07 30 e4 09 d0 a9 00 01 ff ff 75 18 85 c0 74 0e 8b 07 84 c0 74 08 f3 90 8b 07 84 c0 <75> f8 66 c7 07 01 00 c3 f6 c4 01 75 04 c6 47 01 00 48 c7 c0 40 29 RSP: 0018:ffffc90001e87d08 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000101 RBX: ffff8887f96f0000 RCX: ffff8887f96f0000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8887f96f0658 RBP: 000000000000000d R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8887f50b7080 R13: ffffffff82424480 R14: ffffffff82424480 R15: ffff8887f50b70c0 ptrace_may_access+0x1e/0x50 do_task_stat+0x7b/0xd90 ? do_filp_open+0xab/0x100 proc_single_show+0x54/0xc0 ? __kmalloc+0x183/0x210 seq_read+0xbb/0x3c0 vfs_read+0xc6/0x150 ksys_read+0x6b/0x100 do_syscall_64+0x3d/0x120 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f666796082e Code: c0 e9 f6 fe ff ff 50 48 8d 3d b6 5d 0a 00 e8 e9 fd 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28 RSP: 002b:00007ffe26688b38 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007f6667a58958 RCX: 00007f666796082e RDX: 0000000000000400 RSI: 000000000153e590 RDI: 0000000000000004 RBP: 00007f6667a58950 R08: 00007f6667a36120 R09: 00007ffe266889e0 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004 R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffe2668aee9 ... sysrq: Terminate All Tasks rcu: INFO: rcu_sched self-detected stall on CPU rcu: 14-....: (83876 ticks this GP) idle=216/1/0x4000000000000002 softirq=454/454 fqs=20970 (t=84003 jiffies g=-755 q=2695) NMI backtrace for cpu 14 CPU: 14 PID: 520 Comm: pidof Tainted: G D 5.5.7 #1 Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./X470 Taichi, BIOS P3.50 07/18/2019 Call Trace: dump_stack+0x50/0x70 nmi_cpu_backtrace.cold+0x14/0x53 ? lapic_can_unplug_cpu.cold+0x44/0x44 nmi_trigger_cpumask_backtrace+0x7b/0x88 rcu_dump_cpu_stacks+0x7b/0xa9 rcu_sched_clock_irq.cold+0x152/0x39b update_process_times+0x1f/0x50 tick_sched_timer+0x40/0x90 ? tick_sched_do_timer+0x50/0x50 __hrtimer_run_queues+0xdd/0x180 hrtimer_interrupt+0x108/0x230 smp_apic_timer_interrupt+0x53/0xa0 apic_timer_interrupt+0xf/0x20 RIP: 0010:queued_spin_lock_slowpath+0x3d/0x1a0 Code: 3e f0 0f ba 2f 08 0f 92 c0 0f b6 c0 c1 e0 08 89 c2 8b 07 30 e4 09 d0 a9 00 01 ff ff 75 18 85 c0 74 0e 8b 07 84 c0 74 08 f3 90 <8b> 07 84 c0 75 f8 66 c7 07 01 00 c3 f6 c4 01 75 04 c6 47 01 00 48 RSP: 0018:ffffc90001e87d08 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000101 RBX: ffff8887f96f0000 RCX: ffff8887f96f0000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8887f96f0658 RBP: 000000000000000d R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8887f50b7080 R13: ffffffff82424480 R14: ffffffff82424480 R15: ffff8887f50b70c0 ptrace_may_access+0x1e/0x50 do_task_stat+0x7b/0xd90 ? do_filp_open+0xab/0x100 proc_single_show+0x54/0xc0 ? __kmalloc+0x183/0x210 seq_read+0xbb/0x3c0 vfs_read+0xc6/0x150 ksys_read+0x6b/0x100 do_syscall_64+0x3d/0x120 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f666796082e Code: c0 e9 f6 fe ff ff 50 48 8d 3d b6 5d 0a 00 e8 e9 fd 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28 RSP: 002b:00007ffe26688b38 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007f6667a58958 RCX: 00007f666796082e RDX: 0000000000000400 RSI: 000000000153e590 RDI: 0000000000000004 RBP: 00007f6667a58950 R08: 00007f6667a36120 R09: 00007ffe266889e0 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004 R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffe2668aee9 rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 14-... } 21041 jiffies s: 45 root: 0x4000/. rcu: blocking rcu_node structures: Task dump for CPU 14: pidof R running task 0 520 1 0x8000000c Call Trace: ? do_syscall_64+0x3d/0x120 ? entry_SYSCALL_64_after_hwframe+0x44/0xa9 rcu: INFO: rcu_sched self-detected stall on CPU rcu: 14-....: (146878 ticks this GP) idle=216/1/0x4000000000000002 softirq=454/454 fqs=36715 (t=147006 jiffies g=-755 q=3376) NMI backtrace for cpu 14 CPU: 14 PID: 520 Comm: pidof Tainted: G D 5.5.7 #1 Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./X470 Taichi, BIOS P3.50 07/18/2019 Call Trace: dump_stack+0x50/0x70 nmi_cpu_backtrace.cold+0x14/0x53 ? lapic_can_unplug_cpu.cold+0x44/0x44 nmi_trigger_cpumask_backtrace+0x7b/0x88 rcu_dump_cpu_stacks+0x7b/0xa9 rcu_sched_clock_irq.cold+0x152/0x39b update_process_times+0x1f/0x50 tick_sched_timer+0x40/0x90 ? tick_sched_do_timer+0x50/0x50 __hrtimer_run_queues+0xdd/0x180 hrtimer_interrupt+0x108/0x230 smp_apic_timer_interrupt+0x53/0xa0 apic_timer_interrupt+0xf/0x20 RIP: 0010:queued_spin_lock_slowpath+0x3d/0x1a0 Code: 3e f0 0f ba 2f 08 0f 92 c0 0f b6 c0 c1 e0 08 89 c2 8b 07 30 e4 09 d0 a9 00 01 ff ff 75 18 85 c0 74 0e 8b 07 84 c0 74 08 f3 90 <8b> 07 84 c0 75 f8 66 c7 07 01 00 c3 f6 c4 01 75 04 c6 47 01 00 48 RSP: 0018:ffffc90001e87d08 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000101 RBX: ffff8887f96f0000 RCX: ffff8887f96f0000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8887f96f0658 RBP: 000000000000000d R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8887f50b7080 R13: ffffffff82424480 R14: ffffffff82424480 R15: ffff8887f50b70c0 ptrace_may_access+0x1e/0x50 do_task_stat+0x7b/0xd90 ? do_filp_open+0xab/0x100 proc_single_show+0x54/0xc0 ? __kmalloc+0x183/0x210 seq_read+0xbb/0x3c0 vfs_read+0xc6/0x150 ksys_read+0x6b/0x100 do_syscall_64+0x3d/0x120 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f666796082e Code: c0 e9 f6 fe ff ff 50 48 8d 3d b6 5d 0a 00 e8 e9 fd 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28 RSP: 002b:00007ffe26688b38 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007f6667a58958 RCX: 00007f666796082e RDX: 0000000000000400 RSI: 000000000153e590 RDI: 0000000000000004 RBP: 00007f6667a58950 R08: 00007f6667a36120 R09: 00007ffe266889e0 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004 R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffe2668aee9 rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 14-... } 85041 jiffies s: 45 root: 0x4000/. rcu: blocking rcu_node structures: Task dump for CPU 14: pidof R running task 0 520 1 0x8000000c Call Trace: ? do_syscall_64+0x3d/0x120 ? entry_SYSCALL_64_after_hwframe+0x44/0xa9 rcu: INFO: rcu_sched self-detected stall on CPU rcu: 14-....: (209792 ticks this GP) idle=216/1/0x4000000000000002 softirq=454/454 fqs=52439 (t=210009 jiffies g=-755 q=3747) NMI backtrace for cpu 14 CPU: 14 PID: 520 Comm: pidof Tainted: G D 5.5.7 #1 Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./X470 Taichi, BIOS P3.50 07/18/2019 Call Trace: dump_stack+0x50/0x70 nmi_cpu_backtrace.cold+0x14/0x53 ? lapic_can_unplug_cpu.cold+0x44/0x44 nmi_trigger_cpumask_backtrace+0x7b/0x88 rcu_dump_cpu_stacks+0x7b/0xa9 rcu_sched_clock_irq.cold+0x152/0x39b update_process_times+0x1f/0x50 tick_sched_timer+0x40/0x90 ? tick_sched_do_timer+0x50/0x50 __hrtimer_run_queues+0xdd/0x180 hrtimer_interrupt+0x108/0x230 smp_apic_timer_interrupt+0x53/0xa0 apic_timer_interrupt+0xf/0x20 RIP: 0010:queued_spin_lock_slowpath+0x3d/0x1a0 Code: 3e f0 0f ba 2f 08 0f 92 c0 0f b6 c0 c1 e0 08 89 c2 8b 07 30 e4 09 d0 a9 00 01 ff ff 75 18 85 c0 74 0e 8b 07 84 c0 74 08 f3 90 <8b> 07 84 c0 75 f8 66 c7 07 01 00 c3 f6 c4 01 75 04 c6 47 01 00 48 RSP: 0018:ffffc90001e87d08 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000101 RBX: ffff8887f96f0000 RCX: ffff8887f96f0000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8887f96f0658 RBP: 000000000000000d R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8887f50b7080 R13: ffffffff82424480 R14: ffffffff82424480 R15: ffff8887f50b70c0 ptrace_may_access+0x1e/0x50 do_task_stat+0x7b/0xd90 ? do_filp_open+0xab/0x100 proc_single_show+0x54/0xc0 ? __kmalloc+0x183/0x210 seq_read+0xbb/0x3c0 vfs_read+0xc6/0x150 ksys_read+0x6b/0x100 do_syscall_64+0x3d/0x120 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f666796082e Code: c0 e9 f6 fe ff ff 50 48 8d 3d b6 5d 0a 00 e8 e9 fd 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28 RSP: 002b:00007ffe26688b38 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007f6667a58958 RCX: 00007f666796082e RDX: 0000000000000400 RSI: 000000000153e590 RDI: 0000000000000004 RBP: 00007f6667a58950 R08: 00007f6667a36120 R09: 00007ffe266889e0 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004 R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffe2668aee9 rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 14-... } 150577 jiffies s: 45 root: 0x4000/. rcu: blocking rcu_node structures: Task dump for CPU 14: pidof R running task 0 520 1 0x8000000c Call Trace: ? do_syscall_64+0x3d/0x120 ? entry_SYSCALL_64_after_hwframe+0x44/0xa9