syzbot

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10500 ticks this GP) idle=8834/1/0x4000000000000000 softirq=23216/23216 fqs=0
	(t=10502 jiffies g=27737 q=82 ncpus=2)
rcu: rcu_preempt kthread timer wakeup didn't happen for 10502 jiffies! g27737 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=18961
rcu: rcu_preempt kthread starved for 10505 jiffies! g27737 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
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:27776 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:2168
 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 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:741
CPU: 0 PID: 7077 Comm: syz.0.407 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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 de 6c 48 f7 48 89 df e8 36 32 49 f7 e8 d1 27 6c f7 fb bf 01 00 00 00 <e8> f6 a7 3c f7 65 8b 05 27 31 e7 75 85 c0 74 02 5b c3 e8 c4 42 e5
RSP: 0018:ffffc90004467b98 EFLAGS: 00000282
RAX: b1ed92f7d9505c00 RBX: ffff888078cfc0c0 RCX: b1ed92f7d9505c00
RDX: dffffc0000000000 RSI: ffffffff8a6c0600 RDI: 0000000000000001
RBP: ffff888078cfc558 R08: dffffc0000000000 R09: ffffed100f19f819
R10: ffffed100f19f819 R11: 1ffff1100f19f818 R12: 1ffff1100f19f8ab
R13: 0000000000000021 R14: dffffc0000000000 R15: 0000000000000000
FS:  000055555e3d5500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9e5dff6d58 CR3: 0000000064d50000 CR4: 00000000003506f0
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+0xb7/0x1240 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/0x180 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:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9e5fc6ef22
Code: 29 fe 48 85 ff 74 05 e8 fc b6 00 00 48 89 df e8 14 5a 0a 00 e8 9f c4 00 00 48 89 c3 eb d5 66 2e 0f 1f 84 00 00 00 00 00 41 57 <41> 56 41 55 41 54 55 53 48 83 ec 38 80 7f 4e 00 44 8b 6f 48 88 4c
RSP: 002b:00007ffcca3e5d30 EFLAGS: 00000202
RAX: 00007f9e5ffe6090 RBX: 00007f9e60b15720 RCX: 0000000000000000
RDX: 00007f9e5ffe6128 RSI: 000000000000001d RDI: 00007f9e60b15720
RBP: 00007f9e5ffe6128 R08: 0000000000000000 R09: 0000000000000009
R10: 00007ffcca3e5ef0 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000009 R14: 00000000000525b2 R15: 00007ffcca3e5f10
 </TASK>