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[73.241.150.58]) by smtp.gmail.com with ESMTPSA id gn5sm369103pjb.23.2020.07.22.11.22.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 22 Jul 2020 11:22:42 -0700 (PDT) Subject: Re: INFO: rcu detected stall in seq_read (2) To: syzbot , a@unstable.cc, b.a.t.m.a.n@lists.open-mesh.org, corbet@lwn.net, davem@davemloft.net, fweisbec@gmail.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, mareklindner@neomailbox.ch, mingo@kernel.org, netdev@vger.kernel.org, sw@simonwunderlich.de, syzkaller-bugs@googlegroups.com, tglx@linutronix.de, vasundhara-v.volam@broadcom.com References: <000000000000b217d105ab0b8ae4@google.com> From: Eric Dumazet Message-ID: <435c3097-9174-f45b-b9bb-42bc377e43e2@gmail.com> Date: Wed, 22 Jul 2020 11:22:41 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <000000000000b217d105ab0b8ae4@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On 7/22/20 11:02 AM, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 4fa640dc Merge tag 'vfio-v5.8-rc7' of git://github.com/awi.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=145cac30900000 > kernel config: https://syzkaller.appspot.com/x/.config?x=f87a5e4232fdb267 > dashboard link: https://syzkaller.appspot.com/bug?extid=c28b5fee66fd3b7f766e > compiler: gcc (GCC) 10.1.0-syz 20200507 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17e23ac8900000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1198c440900000 > > The issue was bisected to: > > commit 53e233ea2fa9fa7e2405e95070981f327d90e519 > Author: Vasundhara Volam > Date: Thu Oct 4 05:43:52 2018 +0000 > > devlink: Add Documentation/networking/devlink-params-bnxt.txt Probably bogus bisection. This rather looks like a bug in taprio packet scheduler. > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15e22b94900000 > final oops: https://syzkaller.appspot.com/x/report.txt?x=17e22b94900000 > console output: https://syzkaller.appspot.com/x/log.txt?x=13e22b94900000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+c28b5fee66fd3b7f766e@syzkaller.appspotmail.com > Fixes: 53e233ea2fa9 ("devlink: Add Documentation/networking/devlink-params-bnxt.txt") > > hrtimer: interrupt took 6305559 ns > rcu: INFO: rcu_preempt self-detected stall on CPU > rcu: 1-...!: (1 GPs behind) idle=91e/1/0x4000000000000000 softirq=10105/10107 fqs=1 > (t=18319 jiffies g=8905 q=457) > NMI backtrace for cpu 1 > CPU: 1 PID: 4008 Comm: systemd-journal Not tainted 5.8.0-rc6-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: > > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x18f/0x20d lib/dump_stack.c:118 > nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101 > nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62 > trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] > rcu_dump_cpu_stacks+0x194/0x1cf kernel/rcu/tree_stall.h:320 > print_cpu_stall kernel/rcu/tree_stall.h:553 [inline] > check_cpu_stall kernel/rcu/tree_stall.h:627 [inline] > rcu_pending kernel/rcu/tree.c:3489 [inline] > rcu_sched_clock_irq.cold+0x5b3/0xccc kernel/rcu/tree.c:2504 > update_process_times+0x25/0x60 kernel/time/timer.c:1737 > tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:176 > tick_sched_timer+0x108/0x290 kernel/time/tick-sched.c:1320 > __run_hrtimer kernel/time/hrtimer.c:1520 [inline] > __hrtimer_run_queues+0x1d5/0xfc0 kernel/time/hrtimer.c:1584 > hrtimer_interrupt+0x32a/0x930 kernel/time/hrtimer.c:1646 > local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1080 [inline] > __sysvec_apic_timer_interrupt+0x142/0x5e0 arch/x86/kernel/apic/apic.c:1097 > asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711 > > __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline] > run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline] > sysvec_apic_timer_interrupt+0xe0/0x120 arch/x86/kernel/apic/apic.c:1091 > asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:585 > RIP: 0010:format_decode+0x0/0xad0 lib/vsprintf.c:2329 > Code: c7 c7 10 05 af 8a be 10 00 00 00 e8 5a c3 46 00 48 c7 c7 20 78 0d 8a e9 6e f2 e2 fd 0f 1f 40 00 66 2e 0f 1f 84 00 00 00 00 00 <41> 57 41 56 41 55 41 54 55 48 89 f5 53 48 bb 00 00 00 00 00 fc ff > RSP: 0018:ffffc90001077a10 EFLAGS: 00000293 > RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffffffff83b0a497 > RDX: ffff888093224040 RSI: ffffc90001077a80 RDI: ffffffff884e6293 > RBP: ffffffff884e6293 R08: 0000000000000001 R09: ffff8880952a63d1 > R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880952a63d2 > R13: ffffffff884e6293 R14: 0000000000000025 R15: ffffc90001077b30 > vsnprintf+0x155/0x14f0 lib/vsprintf.c:2572 > seq_vprintf fs/seq_file.c:379 [inline] > seq_printf+0x195/0x240 fs/seq_file.c:394 > proc_pid_status+0x1c6d/0x24b0 fs/proc/array.c:424 > proc_single_show+0x116/0x1e0 fs/proc/base.c:766 > seq_read+0x432/0x1070 fs/seq_file.c:208 > vfs_read+0x1df/0x520 fs/read_write.c:479 > ksys_read+0x12d/0x250 fs/read_write.c:607 > do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > RIP: 0033:0x7f0fc43d9910 > Code: Bad RIP value. > RSP: 002b:00007ffdcb193978 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 > RAX: ffffffffffffffda RBX: 000055b1476b96f0 RCX: 00007f0fc43d9910 > RDX: 0000000000000800 RSI: 000055b1476b8b00 RDI: 0000000000000013 > RBP: 00007f0fc4694440 R08: 00007f0fc4697fc8 R09: 0000000000000410 > R10: 000055b1476b96f0 R11: 0000000000000246 R12: 0000000000000800 > R13: 0000000000000d68 R14: 000055b1476b8b00 R15: 00007f0fc4693900 > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > syzbot can test patches for this issue, for details see: > https://goo.gl/tpsmEJ#testing-patches >