syzbot

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (10500 ticks this GP) idle=066c/1/0x4000000000000000 softirq=25241/25241 fqs=630
	(t=10502 jiffies g=34589 q=157 ncpus=2)
rcu: rcu_preempt kthread starved for 9242 jiffies! g34589 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:27280 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 0 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:741
CPU: 1 PID: 6670 Comm: syz.3.459 Not tainted 6.1.147-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: f5 ff 0f 1f 00 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 2e 31 43 f7 48 89 df e8 86 f6 43 f7 e8 91 e8 66 f7 fb bf 01 00 00 00 <e8> 36 74 37 f7 65 8b 05 07 35 e2 75 85 c0 74 02 5b c3 e8 54 46 e0
RSP: 0018:ffffc9000d527bb8 EFLAGS: 00000286
RAX: 79ffde1bd095e200 RBX: ffff888055a040c0 RCX: 79ffde1bd095e200
RDX: dffffc0000000000 RSI: ffffffff8a8c0460 RDI: 0000000000000001
RBP: ffff888055a04558 R08: dffffc0000000000 R09: ffffed100ab40819
R10: ffffed100ab40819 R11: 1ffff1100ab40818 R12: 1ffff1100ab408ab
R13: 0000000000000021 R14: dffffc0000000000 R15: 0000000000000000
FS:  00007f05a26ec6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000006b000 CR3: 0000000073603000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 spin_unlock_irq include/linux/spinlock.h:401 [inline]
 get_signal+0x1163/0x1350 kernel/signal.c:2874
 arch_do_signal_or_restart+0xb0/0x1230 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f05a178e9a7
Code: ff ff 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 a8 ff ff ff f7 d8 64 89
RSP: 002b:00007f05a26ec0e8 EFLAGS: 00000246
RAX: 00000000000000ca RBX: 00007f05a19b5fa8 RCX: 00007f05a178e9a9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f05a19b5fa8
RBP: 00007f05a19b5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f05a19b5fac
R13: 0000000000000000 R14: 00007ffd0c75f7b0 R15: 00007ffd0c75f898
 </TASK>
sched: RT throttling activated
hrtimer: interrupt took 484949333 ns