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Wed, 04 Mar 2020 00:34:01 -0800 (PST) MIME-Version: 1.0 References: <000000000000dd909105a002ebe6@google.com> <01d56a46-2ed1-9953-9824-f32e778beea4@moonlit-rail.com> <60c24894-f0ab-fb41-b0f3-e6c9f940a955@moonlit-rail.com> In-Reply-To: <60c24894-f0ab-fb41-b0f3-e6c9f940a955@moonlit-rail.com> From: Dmitry Vyukov Date: Wed, 4 Mar 2020 09:33:50 +0100 Message-ID: Subject: Re: INFO: rcu detected stall in sys_keyctl To: Kris Karas Cc: LKML Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 4, 2020 at 9:32 AM Kris Karas wrote: > > Dmitry Vyukov wrote: > > syzbot wrote: > >> Call Trace: > >> > >> __dump_stack lib/dump_stack.c:77 [inline] > >> dump_stack+0x197/0x210 lib/dump_stack.c:118 > >> nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101 > >> nmi_trigger_cpumask_backtrace+0x23b/0x28b lib/nmi_backtrace.c:62 > >> arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 > >> trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] > >> rcu_dump_cpu_stacks+0x183/0x1cf kernel/rcu/tree_stall.h:254 > >> print_cpu_stall kernel/rcu/tree_stall.h:475 [inline] > >> check_cpu_stall kernel/rcu/tree_stall.h:549 [inline] > >> rcu_pending kernel/rcu/tree.c:3030 [inline] > >> rcu_sched_clock_irq.cold+0x51a/0xc37 kernel/rcu/tree.c:2276 > >> update_process_times+0x2d/0x70 kernel/time/timer.c:1726 > >> tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:171 > >> tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1314 > >> __run_hrtimer kernel/time/hrtimer.c:1517 [inline] > >> __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1579 > >> hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1641 > >> local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1119 [inline] > >> smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1144 > >> apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 > >> > >> > > +lib/mpi maintainers > > > > I wonder if this can also be triggered by remote actors (tls, wifi, usb, etc). > > > > This looks somewhat similar to an OOPS + rcu stall I reported earlier in > reply to Greg KH's announcement of 5.5.7: > > 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 > > > 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). > > Kris Hi Kris, Please re-send this to full To/Cc list. Nobody reads LKML/syzbot per se.