rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4053/1:b..l (detected by 1, t=10502 jiffies, g=5813, q=291) task:udevd state:R running task stack: 0 pid: 4053 ppid: 3644 flags:0x00000004 Call trace: __switch_to+0x2f4/0x558 arch/arm64/kernel/process.c:521 context_switch kernel/sched/core.c:5030 [inline] __schedule+0xe00/0x1c0c kernel/sched/core.c:6376 preempt_schedule_common+0x138/0x218 kernel/sched/core.c:6552 preempt_schedule+0x64/0x84 kernel/sched/core.c:6577 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline] _raw_spin_unlock_irqrestore+0x108/0x14c kernel/locking/spinlock.c:194 spin_unlock_irqrestore include/linux/spinlock.h:418 [inline] __wake_up_common_lock kernel/sched/wait.c:140 [inline] __wake_up_sync_key+0x11c/0x178 kernel/sched/wait.c:205 sock_def_readable+0x150/0x278 net/core/sock.c:3093 unix_dgram_sendmsg+0xcc8/0x1188 net/unix/af_unix.c:1935 sock_sendmsg_nosec net/socket.c:704 [inline] __sock_sendmsg net/socket.c:716 [inline] sock_write_iter+0x23c/0x31c net/socket.c:1079 call_write_iter include/linux/fs.h:2172 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x7c8/0xa2c fs/read_write.c:594 ksys_write+0x120/0x210 fs/read_write.c:647 __do_sys_write fs/read_write.c:659 [inline] __se_sys_write fs/read_write.c:656 [inline] __arm64_sys_write+0x7c/0x90 fs/read_write.c:656 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 rcu: rcu_preempt kthread starved for 10491 jiffies! g5813 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 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: 0 pid: 15 ppid: 2 flags:0x00000008 Call trace: __switch_to+0x2f4/0x558 arch/arm64/kernel/process.c:521 context_switch kernel/sched/core.c:5030 [inline] __schedule+0xe00/0x1c0c kernel/sched/core.c:6376 schedule+0x11c/0x1c8 kernel/sched/core.c:6459 schedule_timeout+0x180/0x2c8 kernel/time/timer.c:1914 rcu_gp_fqs_loop+0x25c/0x11f0 kernel/rcu/tree.c:1972 rcu_gp_kthread+0xc4/0x2a8 kernel/rcu/tree.c:2145 kthread+0x374/0x454 kernel/kthread.c:334 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870 rcu: Stack dump where RCU GP kthread last ran: Task dump for CPU 1: task:syz.1.17 state:R running task stack: 0 pid: 4199 ppid: 4134 flags:0x00000001 Call trace: dump_backtrace+0x0/0x43c arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 sched_show_task+0x3c8/0x4b4 kernel/sched/core.c:8640 dump_cpu_task+0x84/0xa8 kernel/sched/core.c:10927 rcu_check_gp_kthread_starvation+0x1e8/0x274 kernel/rcu/tree_stall.h:488 print_other_cpu_stall+0x1a24/0x1c10 kernel/rcu/tree_stall.h:592 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline] rcu_pending kernel/rcu/tree.c:3932 [inline] rcu_sched_clock_irq+0x1558/0x1810 kernel/rcu/tree.c:2619 update_process_times+0x1c4/0x260 kernel/time/timer.c:1818 tick_sched_handle kernel/time/tick-sched.c:254 [inline] tick_sched_timer+0x30c/0x4bc kernel/time/tick-sched.c:1473 __run_hrtimer kernel/time/hrtimer.c:1690 [inline] __hrtimer_run_queues+0x3fc/0xb6c kernel/time/hrtimer.c:1754 hrtimer_interrupt+0x2bc/0xb5c kernel/time/hrtimer.c:1816 timer_handler drivers/clocksource/arm_arch_timer.c:659 [inline] arch_timer_handler_virt+0x74/0x88 drivers/clocksource/arm_arch_timer.c:670 handle_percpu_devid_irq+0x29c/0x76c kernel/irq/chip.c:930 generic_handle_irq_desc include/linux/irqdesc.h:158 [inline] handle_irq_desc kernel/irq/irqdesc.c:652 [inline] handle_domain_irq+0x144/0x1fc kernel/irq/irqdesc.c:707 gic_handle_irq+0x78/0x1c8 drivers/irqchip/irq-gic-v3.c:765 call_on_irq_stack+0x24/0x4c arch/arm64/kernel/entry.S:899 do_interrupt_handler+0x6c/0x88 arch/arm64/kernel/entry-common.c:267 el1_interrupt+0x30/0x58 arch/arm64/kernel/entry-common.c:454 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:470 el1h_64_irq+0x78/0x7c arch/arm64/kernel/entry.S:522 arch_local_irq_restore+0x8/0x10 arch/arm64/include/asm/irqflags.h:122 lock_is_held include/linux/lockdep.h:287 [inline] ___might_sleep+0x98/0x4d4 kernel/sched/core.c:9605 __might_sleep+0x98/0x124 kernel/sched/core.c:9593 __might_fault+0x80/0x128 mm/memory.c:5354 restore_sigframe arch/arm64/kernel/signal.c:506 [inline] __arm64_sys_rt_sigreturn+0x298/0x1fec arch/arm64/kernel/signal.c:558 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584