syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (4 ticks this GP) idle=fb14/1/0x4000000000000000 softirq=48419/48420 fqs=320
rcu: 	(detected by 0, t=10502 jiffies, g=39253, q=100 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 12 Comm: kworker/u8:0 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:kasan_check_range+0x163/0x1b0 mm/kasan/generic.c:201
Code: 89 da 4c 89 d8 4c 29 da e9 46 ff ff ff 48 85 d2 74 18 48 01 ea eb 09 48 83 c0 01 48 39 d0 74 0a 80 38 00 74 f2 e9 75 ff ff ff <5b> b8 01 00 00 00 5d 41 5c c3 cc cc cc cc b8 01 00 00 00 e9 95 70
RSP: 0018:ffffc90000a08d00 EFLAGS: 00000046
RAX: ffffed1006e71655 RBX: ffffed1006e71655 RCX: ffffffff897fecba
RDX: ffffed1006e71655 RSI: 0000000000000008 RDI: ffff88803738b2a0
RBP: ffffed1006e71654 R08: 0000000000000000 R09: ffffed1006e71654
R10: ffff88803738b2a7 R11: ffff88801d6c54b0 R12: 0000000000000000
R13: ffff8880577e8c00 R14: 000000000401004e R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8881249f6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007faa659b3f98 CR3: 00000000566df000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 atomic64_read include/linux/atomic/atomic-instrumented.h:1610 [inline]
 taprio_set_budgets+0x13a/0x310 net/sched/sch_taprio.c:676
 advance_sched+0x5f6/0xc80 net/sched/sch_taprio.c:983
 __run_hrtimer kernel/time/hrtimer.c:1777 [inline]
 __hrtimer_run_queues+0x202/0xc40 kernel/time/hrtimer.c:1841
 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1903
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x3c0 arch/x86/kernel/apic/apic.c:1062
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1056
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:crng_make_state+0x2b5/0x6c0 drivers/char/random.c:394
Code: fc 4d 85 ed 0f 85 cf 01 00 00 e8 c6 53 88 fc 9c 5b 81 e3 00 02 00 00 31 ff 48 89 de e8 84 4e 88 fc 48 85 db 0f 85 59 02 00 00 <48> 83 c4 20 5b 5d 41 5c 41 5d 41 5e 41 5f e9 98 53 88 fc e8 93 53
RSP: 0018:ffffc90000117990 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff85369220
RDX: ffff88801d6c4980 RSI: ffffffff8536922e RDI: 0000000000000007
RBP: 0000000000000000 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 7102910b58e08395 R12: ffff8880b8536df0
R13: 0000000000000200 R14: 0000000000000006 R15: 0000000000000013
 _get_random_bytes+0x120/0x1e0 drivers/char/random.c:406
 eth_random_addr include/linux/etherdevice.h:238 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:826 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:875 [inline]
 nsim_dev_trap_report_work+0x3ad/0xcf0 drivers/net/netdevsim/dev.c:921
 process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257
 process_scheduled_works kernel/workqueue.c:3340 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
rcu: rcu_preempt kthread starved for 9862 jiffies! g39253 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:28328 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x1139/0x6150 kernel/sched/core.c:6863
 __schedule_loop kernel/sched/core.c:6945 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6960
 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1ea/0xaf0 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x26d/0x380 kernel/rcu/tree.c:2285
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82
Code: c6 5f 02 c3 cc cc cc cc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 13 59 12 00 fb f4 <e9> cc 35 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffffff8e007df8 EFLAGS: 000002c6
RAX: 00000000013bc9a5 RBX: 0000000000000000 RCX: ffffffff8b7806d9
RDX: 0000000000000000 RSI: ffffffff8dacdb2d RDI: ffffffff8bf2b300
RBP: fffffbfff1c12f68 R08: 0000000000000001 R09: ffffed101708673d
R10: ffff8880b84339eb R11: ffffffff8e098670 R12: 0000000000000000
R13: ffffffff8e097b40 R14: ffffffff9088aed0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881248f6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007faa659d5d58 CR3: 0000000067343000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:767
 default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:191 [inline]
 do_idle+0x38d/0x510 kernel/sched/idle.c:332
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:430
 rest_init+0x16b/0x2b0 init/main.c:757
 start_kernel+0x3ef/0x4d0 init/main.c:1206
 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:310
 x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:291
 common_startup_64+0x13e/0x148
 </TASK>