syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
	(detected by 0, t=10502 jiffies, g=16689, q=52)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294961165-4294950663), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g16689 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R  running task     stack:27584 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5660 Comm: syz.3.280 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:hlock_class kernel/locking/lockdep.c:209 [inline]
RIP: 0010:mark_lock+0x9e/0x320 kernel/locking/lockdep.c:4569
Code: 41 81 e7 ff 1f 00 00 c1 e8 03 25 f8 03 00 00 48 8d b8 c0 c0 fb 8f be 08 00 00 00 e8 5c 85 5f 00 4c 0f a3 3d 54 11 9f 0e 73 10 <4b> 8d 04 7f c1 e0 06 4c 8d b8 80 3f 94 8f eb 24 48 c7 c0 80 2f 0c
RSP: 0018:ffffc90000dd08a0 EFLAGS: 00000057
RAX: 0000000000000001 RBX: ffff888020b53b80 RCX: ffffffff815caf64
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8ffbc0c8
RBP: 0000000000000000 R08: dffffc0000000000 R09: fffffbfff1ff781a
R10: fffffbfff1ff781a R11: 1ffffffff1ff7819 R12: 0000000000000001
R13: dffffc0000000000 R14: ffff888020b54698 R15: 000000000000005d
FS:  00007fc499c686c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2941ea CR3: 00000000756a9000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 mark_usage kernel/locking/lockdep.c:4483 [inline]
 __lock_acquire+0xc11/0x7c60 kernel/locking/lockdep.c:4966
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
 _raw_spin_lock_irq+0x9f/0xe0 kernel/locking/spinlock.c:170
 __run_hrtimer kernel/time/hrtimer.c:1694 [inline]
 __hrtimer_run_queues+0x5ff/0xc40 kernel/time/hrtimer.c:1754
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa5/0x100 kernel/locking/spinlock.c:194
Code: 74 05 e8 5e 8d cb f7 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> c6 15 9f f7 65 8b 05 a7 13 50 76 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc90002e2fb80 EFLAGS: 00000206
RAX: 034c98aa9953e900 RBX: 0000000000000a02 RCX: 034c98aa9953e900
RDX: dffffc0000000000 RSI: ffffffff8a0b1820 RDI: 0000000000000001
RBP: ffffc90002e2fc10 R08: dffffc0000000000 R09: fffffbfff1ff7819
R10: fffffbfff1ff7819 R11: 1ffffffff1ff7818 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff8880b902a240 R15: 1ffff920005c5f70
 clock_was_set+0x642/0x840 kernel/time/hrtimer.c:960
 do_settimeofday64+0x575/0x720 kernel/time/timekeeping.c:1328
 __do_sys_clock_settime kernel/time/posix-timers.c:1125 [inline]
 __se_sys_clock_settime kernel/time/posix-timers.c:1113 [inline]
 __x64_sys_clock_settime+0x223/0x270 kernel/time/posix-timers.c:1113
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fc49ba00ba9
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc499c68038 EFLAGS: 00000246 ORIG_RAX: 00000000000000e3
RAX: ffffffffffffffda RBX: 00007fc49bc47fa0 RCX: 00007fc49ba00ba9
RDX: 0000000000000000 RSI: 0000200000000240 RDI: 0000000000000000
RBP: 00007fc49ba83e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc49bc48038 R14: 00007fc49bc47fa0 R15: 00007ffe1d31e4e8
 </TASK>