Dear Linux Developer, Recently when using our tool to fuzz kernel, the following crash was triggered: HEAD commit: 64570fbc14f8 Linux 5.15-rc5 git tree: upstream compiler: clang 12.0.0 console output: https://drive.google.com/file/d/1BOhVEmi3RPIxx-F0LMLsgflaj0r0MyKv/view?usp=sharing kernel config: https://drive.google.com/file/d/1lNwvovjLNrcuyFGrg05IoSmgO5jaKBBJ/view?usp=sharing Unfortunately, I don't have any reproducer for this crash yet. rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-...!: (88 ticks this GP) idle=4c5/1/0x4000000000000000 softirq=42739/42739 fqs=1 (t=15633 jiffies g=62957 q=125) rcu: rcu_preempt kthread starved for 15193 jiffies! g62957 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:R running task stack:27696 pid: 14 ppid: 2 flags:0x00004000 Call Trace: __schedule+0xc1a/0x11e0 schedule+0x14b/0x210 schedule_timeout+0x1b4/0x310 rcu_gp_fqs_loop+0x1fd/0x770 rcu_gp_kthread+0xa5/0x340 kthread+0x419/0x510 ret_from_fork+0x1f/0x30 rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 0 CPU: 0 PID: 13 Comm: ksoftirqd/0 Not tainted 5.15.0-rc5+ #14 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Call Trace: <IRQ> dump_stack_lvl+0x1d8/0x2c4 nmi_cpu_backtrace+0x452/0x480 nmi_trigger_cpumask_backtrace+0x1a3/0x330 rcu_check_gp_kthread_starvation+0x1f9/0x270 rcu_sched_clock_irq+0x1de4/0x2bc0 update_process_times+0x1ab/0x220 tick_sched_timer+0x2a0/0x440 __hrtimer_run_queues+0x51a/0xae0 hrtimer_interrupt+0x3c9/0x1130 __sysvec_apic_timer_interrupt+0xf9/0x280 sysvec_apic_timer_interrupt+0x8c/0xb0 </IRQ> asm_sysvec_apic_timer_interrupt+0x12/0x20 RIP: 0010:e1000_clean+0x15ad/0x40b0 Code: c5 c8 04 00 00 4c 89 eb 48 c1 eb 03 42 80 3c 23 00 74 08 4c 89 ef e8 a2 2c 65 fc 49 8b 45 00 b9 9d 00 00 00 89 88 d0 00 00 00 <42> 80 3c 23 00 74 08 4c 89 ef e8 84 2c 65 fc 49 8b 45 00 8b 40 08 RSP: 0018:ffffc90000707840 EFLAGS: 00000246 RAX: ffffc900065c0000 RBX: 1ffff1100371f229 RCX: 000000000000009d RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90000707ac8 R08: ffffffff856f35c6 R09: ffffed100371f2a7 R10: ffffed100371f2a7 R11: 0000000000000000 R12: dffffc0000000000 R13: ffff88801b8f9148 R14: 0000000000004e20 R15: 1ffff920000e0f2c __napi_poll+0xbd/0x550 net_rx_action+0x67b/0xfc0 __do_softirq+0x372/0x783 run_ksoftirqd+0xa2/0x100 smpboot_thread_fn+0x570/0xa20 kthread+0x419/0x510 ret_from_fork+0x1f/0x30 NMI backtrace for cpu 0 CPU: 0 PID: 13 Comm: ksoftirqd/0 Not tainted 5.15.0-rc5+ #14 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Call Trace: <IRQ> dump_stack_lvl+0x1d8/0x2c4 nmi_cpu_backtrace+0x452/0x480 nmi_trigger_cpumask_backtrace+0x1a3/0x330 rcu_dump_cpu_stacks+0x22d/0x390 rcu_sched_clock_irq+0x1de9/0x2bc0 update_process_times+0x1ab/0x220 tick_sched_timer+0x2a0/0x440 __hrtimer_run_queues+0x51a/0xae0 hrtimer_interrupt+0x3c9/0x1130 __sysvec_apic_timer_interrupt+0xf9/0x280 sysvec_apic_timer_interrupt+0x8c/0xb0 </IRQ> asm_sysvec_apic_timer_interrupt+0x12/0x20 RIP: 0010:e1000_clean+0x15ad/0x40b0 Code: c5 c8 04 00 00 4c 89 eb 48 c1 eb 03 42 80 3c 23 00 74 08 4c 89 ef e8 a2 2c 65 fc 49 8b 45 00 b9 9d 00 00 00 89 88 d0 00 00 00 <42> 80 3c 23 00 74 08 4c 89 ef e8 84 2c 65 fc 49 8b 45 00 8b 40 08 RSP: 0018:ffffc90000707840 EFLAGS: 00000246 RAX: ffffc900065c0000 RBX: 1ffff1100371f229 RCX: 000000000000009d RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90000707ac8 R08: ffffffff856f35c6 R09: ffffed100371f2a7 R10: ffffed100371f2a7 R11: 0000000000000000 R12: dffffc0000000000 R13: ffff88801b8f9148 R14: 0000000000004e20 R15: 1ffff920000e0f2c __napi_poll+0xbd/0x550 net_rx_action+0x67b/0xfc0 __do_softirq+0x372/0x783 run_ksoftirqd+0xa2/0x100 smpboot_thread_fn+0x570/0xa20 kthread+0x419/0x510 ret_from_fork+0x1f/0x30 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: c8 04 00 00 enterq $0x4,$0x0 4: 4c 89 eb mov %r13,%rbx 7: 48 c1 eb 03 shr $0x3,%rbx b: 42 80 3c 23 00 cmpb $0x0,(%rbx,%r12,1) 10: 74 08 je 0x1a 12: 4c 89 ef mov %r13,%rdi 15: e8 a2 2c 65 fc callq 0xfc652cbc 1a: 49 8b 45 00 mov 0x0(%r13),%rax 1e: b9 9d 00 00 00 mov $0x9d,%ecx 23: 89 88 d0 00 00 00 mov %ecx,0xd0(%rax) * 29: 42 80 3c 23 00 cmpb $0x0,(%rbx,%r12,1) <-- trapping instruction 2e: 74 08 je 0x38 30: 4c 89 ef mov %r13,%rdi 33: e8 84 2c 65 fc callq 0xfc652cbc 38: 49 8b 45 00 mov 0x0(%r13),%rax 3c: 8b 40 08 mov 0x8(%rax),%eax Best, Wei
