rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=78969, q=59) rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294997021-4294986519), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10502 jiffies! g78969 f0x2 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:29168 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4339 [inline] __schedule+0x916/0x2410 kernel/sched/core.c:5147 schedule+0xcf/0x270 kernel/sched/core.c:5226 schedule_timeout+0x14a/0x250 kernel/time/timer.c:1892 rcu_gp_fqs_loop kernel/rcu/tree.c:2004 [inline] rcu_gp_kthread+0xd07/0x2280 kernel/rcu/tree.c:2177 kthread+0x3b1/0x4a0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 0 CPU: 0 PID: 25194 Comm: syz-executor.0 Not tainted 5.12.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x141/0x1d7 lib/dump_stack.c:120 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_check_gp_kthread_starvation.cold+0x1cc/0x1d1 kernel/rcu/tree_stall.h:478 print_other_cpu_stall kernel/rcu/tree_stall.h:583 [inline] check_cpu_stall kernel/rcu/tree_stall.h:708 [inline] rcu_pending kernel/rcu/tree.c:3911 [inline] rcu_sched_clock_irq+0x1d46/0x2080 kernel/rcu/tree.c:2649 update_process_times+0x16d/0x200 kernel/time/timer.c:1796 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1373 __run_hrtimer kernel/time/hrtimer.c:1537 [inline] __hrtimer_run_queues+0x1c0/0xe40 kernel/time/hrtimer.c:1601 hrtimer_interrupt+0x330/0xa00 kernel/time/hrtimer.c:1663 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1089 [inline] __sysvec_apic_timer_interrupt+0x146/0x540 arch/x86/kernel/apic/apic.c:1106 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1100 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:632 RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:163 [inline] RIP: 0010:unwind_next_frame+0x24a/0x1ce0 arch/x86/kernel/unwind_orc.c:443 Code: 00 00 00 fc ff df 89 f2 48 8d 3c 95 e0 f9 d8 8e 48 89 f9 48 c1 e9 03 0f b6 0c 01 48 89 f8 83 e0 07 83 c0 03 38 c8 7c 27 84 c9 <74> 23 48 89 54 24 30 48 89 74 24 28 44 89 5c 24 20 e8 00 52 85 00 RSP: 0018:ffffc9000c45f4a0 EFLAGS: 00000246 RAX: 0000000000000007 RBX: 1ffff9200188be9c RCX: 0000000000000000 RDX: 00000000000062f1 RSI: 00000000000062f1 RDI: ffffffff8eda85a4 RBP: 0000000000000001 R08: ffffffff8bdf1740 R09: 0000000000000001 R10: fffff5200188beba R11: 0000000000084087 R12: ffffc9000c45f5c0 R13: ffffc9000c45f5ad R14: ffffc9000c45f578 R15: ffffffff8162f11b arch_stack_walk+0x7d/0xe0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:121 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:427 [inline] ____kasan_kmalloc mm/kasan/common.c:506 [inline] ____kasan_kmalloc mm/kasan/common.c:465 [inline] __kasan_kmalloc+0x99/0xc0 mm/kasan/common.c:515 kmalloc include/linux/slab.h:556 [inline] tty_alloc_file drivers/tty/tty_io.c:187 [inline] tty_open+0x140/0x1000 drivers/tty/tty_io.c:2144 chrdev_open+0x266/0x770 fs/char_dev.c:414 do_dentry_open+0x4b9/0x11b0 fs/open.c:826 do_open fs/namei.c:3361 [inline] path_openat+0x1c0e/0x27e0 fs/namei.c:3494 do_filp_open+0x190/0x3d0 fs/namei.c:3521 do_sys_openat2+0x16d/0x420 fs/open.c:1187 do_sys_open fs/open.c:1203 [inline] __do_sys_openat fs/open.c:1219 [inline] __se_sys_openat fs/open.c:1214 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1214 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665f9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fb18dde1188 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 00000000004665f9 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00000000004bfce1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60 R13: 00007fffe4ef9aff R14: 00007fb18dde1300 R15: 0000000000022000