rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-...!: (1 ticks this GP) idle=7b6/1/0x4000000000000000 softirq=9700/9700 fqs=0 (t=28690 jiffies g=3765 q=4311) rcu: rcu_preempt kthread starved for 28690 jiffies! g3765 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:14328 pid: 10 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:3774 [inline] __schedule+0x404/0x890 kernel/sched/core.c:4523 schedule+0x38/0xe0 kernel/sched/core.c:4601 schedule_timeout+0x1be/0x2e0 kernel/time/timer.c:1871 rcu_gp_fqs_loop kernel/rcu/tree.c:1925 [inline] rcu_gp_kthread+0x707/0xc60 kernel/rcu/tree.c:2099 kthread+0x145/0x170 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 NMI backtrace for cpu 0 CPU: 0 PID: 8261 Comm: syz-executor.3 Not tainted 5.10.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xa3/0xc8 lib/dump_stack.c:118 nmi_cpu_backtrace.cold.8+0x53/0x6d lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0xd5/0xf0 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0xa2/0xce kernel/rcu/tree_stall.h:318 print_cpu_stall kernel/rcu/tree_stall.h:551 [inline] check_cpu_stall kernel/rcu/tree_stall.h:625 [inline] rcu_pending kernel/rcu/tree.c:3694 [inline] rcu_sched_clock_irq.cold.93+0x61/0x52b kernel/rcu/tree.c:2567 update_process_times+0x50/0x80 kernel/time/timer.c:1709 tick_sched_handle.isra.24+0x1a/0x50 kernel/time/tick-sched.c:176 tick_sched_timer+0x6c/0x80 kernel/time/tick-sched.c:1328 __run_hrtimer kernel/time/hrtimer.c:1519 [inline] __hrtimer_run_queues+0x1e3/0x4f0 kernel/time/hrtimer.c:1583 hrtimer_interrupt+0xf9/0x210 kernel/time/hrtimer.c:1645 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1080 [inline] __sysvec_apic_timer_interrupt+0x8e/0x290 arch/x86/kernel/apic/apic.c:1097 asm_call_irq_on_stack+0xf/0x20 __run_sysvec_on_irqstack arch/x86/include/asm/irq_stack.h:37 [inline] run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:89 [inline] sysvec_apic_timer_interrupt+0xcc/0xf0 arch/x86/kernel/apic/apic.c:1091 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:631 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:653 [inline] RIP: 0010:on_each_cpu+0x61/0xa0 kernel/smp.c:835 Code: e4 6a 04 03 00 48 89 c3 74 52 fa 66 0f 1f 44 00 00 f6 c7 02 75 33 4c 89 e7 ff d5 48 83 3d be 6a 04 03 00 74 39 48 89 df 57 9d <0f> 1f 44 00 00 bf 01 00 00 00 e8 70 94 f7 ff 65 8b 05 d9 25 d9 7e RSP: 0018:ffffc90002defe98 EFLAGS: 00000282 RAX: 000000000000006f RBX: 0000000000000282 RCX: 0000000000000002 RDX: 0000000000000000 RSI: ffffffff83f2aaa3 RDI: 0000000000000282 RBP: ffffffff8126a720 R08: 0000000000000001 R09: 0000000000000001 R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000 R13: 00000000178d9b47 R14: ffffffffce790001 R15: 0000000000000282 clock_was_set+0x13/0x20 kernel/time/hrtimer.c:871 do_settimeofday64+0x179/0x210 kernel/time/timekeeping.c:1331 __do_sys_clock_settime kernel/time/posix-timers.c:1079 [inline] __se_sys_clock_settime kernel/time/posix-timers.c:1067 [inline] __x64_sys_clock_settime+0x64/0xb0 kernel/time/posix-timers.c:1067 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45cba9 Code: 8d 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 5b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f5fc14c6c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000e3 RAX: ffffffffffffffda RBX: 00000000004db5e0 RCX: 000000000045cba9 RDX: 0000000000000000 RSI: 0000000020000400 RDI: 0000000000000000 RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 000000000000007b R14: 00000000004c352c R15: 00007f5fc14c76d4 ------------[ cut here ]------------ WARNING: CPU: 0 PID: 9 at kernel/fork.c:457 free_task_struct kernel/fork.c:175 [inline] WARNING: CPU: 0 PID: 9 at kernel/fork.c:457 free_task+0x4c/0x50 kernel/fork.c:464 Modules linked in: CPU: 0 PID: 9 Comm: ksoftirqd/0 Not tainted 5.10.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:free_task+0x4c/0x50 kernel/fork.c:457 Code: 75 10 48 89 de 48 8b 3d 8a 81 28 04 5b e9 0c 2d 23 00 48 89 df e8 d4 08 03 00 48 89 de 48 8b 3d 72 81 28 04 5b e9 f4 2c 23 00 <0f> 0b eb be 41 55 41 54 55 53 8b 87 94 04 00 00 48 89 fb 85 c0 0f RSP: 0018:ffffc90000cb3e00 EFLAGS: 00010202 RAX: 0000000000000001 RBX: ffff88811d5122c0 RCX: ffffc90000cb3d7c RDX: 0000000000000001 RSI: ffffffff83e86c57 RDI: ffff88811d5122c0 RBP: ffff88813bc2edd8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: ffffffffffffffff R12: ffffffff8362d180 R13: ffff88811d513678 R14: 0000000000000000 R15: ffffffff8125cbe9 FS: 0000000000000000(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000bf3000 CR3: 000000010967d000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_do_batch kernel/rcu/tree.c:2476 [inline] rcu_core+0x4b4/0x890 kernel/rcu/tree.c:2711 __do_softirq+0xe9/0x52f kernel/softirq.c:298 run_ksoftirqd+0x68/0xa0 kernel/softirq.c:653 smpboot_thread_fn+0x1c5/0x280 kernel/smpboot.c:165 kthread+0x145/0x170 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296