syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 0, t=10502 jiffies, g=10753, q=707 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294961880-4294951378), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g10753 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:27088 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_timeout+0x160/0x280 kernel/time/timer.c:2167
 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </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: 5996 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
RIP: 0010:_raw_spin_lock_irqsave+0xac/0xf0 kernel/locking/spinlock.c:162
Code: f7 bf 01 00 00 00 e8 d3 f9 e2 f6 48 8d 7b 18 31 f6 31 d2 31 c9 41 b8 01 00 00 00 45 31 c9 ff 75 08 e8 18 85 ee f6 48 83 c4 08 <48> 89 df e8 bc d4 ef f6 48 c7 04 24 0e 36 e0 45 4b c7 04 27 00 00
RSP: 0018:ffffc900001f0c20 EFLAGS: 00000092
RAX: 9190340e25d60f00 RBX: ffffffff97126588 RCX: 9190340e25d60f00
RDX: 0000000000000000 RSI: ffffffff8aaace60 RDI: ffffffff8afc6b00
RBP: ffffc900001f0cb0 R08: dffffc0000000000 R09: 1ffffffff21b50a0
R10: dffffc0000000000 R11: fffffbfff21b50a1 R12: dffffc0000000000
R13: ffffffff97126580 R14: 0000000000000806 R15: 1ffff9200003e184
FS:  0000555559533500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000006b000 CR3: 000000001bfb0000 CR4: 00000000003506e0
Call Trace:
 <IRQ>
 debug_object_deactivate+0x67/0x350 lib/debugobjects.c:764
 debug_hrtimer_deactivate kernel/time/hrtimer.c:455 [inline]
 debug_deactivate+0x1d/0x1d0 kernel/time/hrtimer.c:511
 __run_hrtimer kernel/time/hrtimer.c:1718 [inline]
 __hrtimer_run_queues+0x2bf/0xc40 kernel/time/hrtimer.c:1814
 hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1876
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline]
 __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:202
Code: 00 f3 0f 1e fa 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 0a 04 ef f6 48 89 df e8 22 d6 ef f6 e8 3d 7c 13 f7 fb bf 01 00 00 00 <e8> 62 f8 e2 f6 65 8b 05 53 41 8b 75 85 c0 74 02 5b c3 e8 70 25 88
RSP: 0018:ffffc90003697c78 EFLAGS: 00000286
RAX: 9190340e25d60f00 RBX: ffff8880611a0000 RCX: 9190340e25d60f00
RDX: dffffc0000000000 RSI: ffffffff8aaabce0 RDI: 0000000000000001
RBP: ffff8880611a0498 R08: ffffffff8e4a8d6f R09: 1ffffffff1c951ad
R10: dffffc0000000000 R11: fffffbfff1c951ae R12: 1ffff1100c234093
R13: 0000000000000021 R14: dffffc0000000000 R15: 0000000000000000
 spin_unlock_irq include/linux/spinlock.h:401 [inline]
 get_signal+0x11f5/0x1400 kernel/signal.c:2905
 arch_do_signal_or_restart+0x9c/0x7b0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f5d34b8f6c9
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:00007fff25d5d1e8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 00007f5d34de5fa0 RCX: 00007f5d34b8f6c9
RDX: 000020000006b000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f5d34c11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5d34de5fa0 R14: 00007f5d34de5fa0 R15: 0000000000000004
 </TASK>