rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 1, t=10502 jiffies, g=18877, q=27) rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294981735-4294971232), jiffies_till_next_fqs=1, root ->qsmask 0x0 syz-executor.0 R running task 26776 11540 10278 0x00004000 Call Trace: sched_show_task kernel/sched/core.c:5952 [inline] sched_show_task.cold+0x2e2/0x343 kernel/sched/core.c:5927 print_other_cpu_stall kernel/rcu/tree_stall.h:430 [inline] check_cpu_stall kernel/rcu/tree_stall.h:558 [inline] rcu_pending kernel/rcu/tree.c:3030 [inline] rcu_sched_clock_irq.cold+0xb35/0xc55 kernel/rcu/tree.c:2276 update_process_times+0x25/0x60 kernel/time/timer.c:1726 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:171 tick_sched_timer+0x4e/0x140 kernel/time/tick-sched.c:1314 __run_hrtimer kernel/time/hrtimer.c:1517 [inline] __hrtimer_run_queues+0x32c/0xdd0 kernel/time/hrtimer.c:1579 hrtimer_interrupt+0x312/0x770 kernel/time/hrtimer.c:1641 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1119 [inline] smp_apic_timer_interrupt+0x15b/0x600 arch/x86/kernel/apic/apic.c:1144 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:deref_stack_reg+0x2a/0xe0 arch/x86/kernel/unwind_orc.c:347 Code: 41 55 49 bd 00 00 00 00 00 fc ff df 41 54 49 89 d4 ba 08 00 00 00 55 48 89 f5 53 48 83 ec 60 48 89 e3 48 c7 04 24 b3 8a b5 41 <48> c7 44 24 08 f8 19 24 89 48 c1 eb 03 48 c7 44 24 10 00 ff 31 81 RSP: 0018:ffffc90016797218 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000000 RBX: ffffc90016797218 RCX: 0000000000000000 RDX: 0000000000000008 RSI: ffffc90016797400 RDI: ffffc90016797430 RBP: ffffc90016797400 R08: ffffffff8acbb536 R09: 0000000000000001 R10: 000000000000c455 R11: 000000000006e027 R12: ffffc90016797470 R13: dffffc0000000000 R14: ffffc90016797480 R15: ffffc90016797430 unwind_next_frame+0x10f4/0x19d0 arch/x86/kernel/unwind_orc.c:548 __unwind_start arch/x86/kernel/unwind_orc.c:655 [inline] __unwind_start+0x474/0x820 arch/x86/kernel/unwind_orc.c:585 unwind_start arch/x86/include/asm/unwind.h:60 [inline] arch_stack_walk+0x57/0xd0 arch/x86/kernel/stacktrace.c:24 stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:123 save_stack+0x1b/0x80 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc mm/kasan/common.c:515 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:488 kmem_cache_alloc_trace+0x153/0x7d0 mm/slab.c:3551 kmalloc include/linux/slab.h:555 [inline] tty_alloc_file drivers/tty/tty_io.c:189 [inline] tty_open+0x138/0xb30 drivers/tty/tty_io.c:2029 chrdev_open+0x219/0x5c0 fs/char_dev.c:414 do_dentry_open+0x4a2/0x1250 fs/open.c:797 do_last fs/namei.c:3490 [inline] path_openat+0x122a/0x32b0 fs/namei.c:3607 do_filp_open+0x192/0x260 fs/namei.c:3637 do_sys_openat2+0x54c/0x740 fs/open.c:1149 do_sys_open+0xc3/0x140 fs/open.c:1165 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45c679 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fada8bc0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fada8bc16d4 RCX: 000000000045c679 RDX: 0000000000000000 RSI: 0000000020000080 RDI: ffffffffffffff9c RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000007f3 R14: 00000000004ca91c R15: 000000000076bf0c rcu: rcu_preempt kthread starved for 10562 jiffies! g18877 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29384 10 2 0x80004000 Call Trace: schedule+0xd0/0x2a0 kernel/sched/core.c:4154 schedule_timeout+0x474/0xba0 kernel/time/timer.c:1895 rcu_gp_fqs_loop kernel/rcu/tree.c:1658 [inline] rcu_gp_kthread+0x9d9/0x17d0 kernel/rcu/tree.c:1818 kthread+0x357/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352