syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P1190/1:b..l
	(detected by 1, t=10502 jiffies, g=7161, q=154 ncpus=2)
task:kworker/1:2     state:R  running task     stack:27256 pid:1190  ppid:2      flags:0x00004000
Workqueue: events_power_efficient gc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 preempt_schedule_notrace+0xd9/0x120 kernel/sched/core.c:6824
 preempt_schedule_notrace_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35
 rcu_is_watching+0x76/0xa0 kernel/rcu/tree.c:722
 rcu_read_lock include/linux/rcupdate.h:792 [inline]
 gc_worker+0x29f/0x13c0 net/netfilter/nf_conntrack_core.c:1515
 process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: rcu_preempt kthread starved for 10518 jiffies! g7161 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:28016 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x303/0x1340 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x99/0x3b0 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
CPU: 0 PID: 4298 Comm: syz-executor126 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:182 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0xc/0x60 kernel/kcov.c:216
Code: 89 fb e8 17 00 00 00 48 8b 3d 40 5a 9d 0c 48 89 de 5b e9 47 22 50 00 00 00 cc cc 00 00 cc 48 8b 04 24 65 48 8b 0d 14 fa 7f 7e <65> 8b 15 15 fa 7f 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75
RSP: 0018:ffffc90003fc79d8 EFLAGS: 00000046
RAX: ffffffff8172b29d RBX: 0000000000000000 RCX: ffff88801cfe8000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003fc7a88 R08: ffffffff8e1fcd2f R09: 1ffffffff1c3f9a5
R10: dffffc0000000000 R11: fffffbfff1c3f9a6 R12: 0000000000000000
R13: dffffc0000000000 R14: 1ffff920007f8f3c R15: dffffc0000000000
FS:  0000555560e743c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000000203a0000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 arch_irqs_disabled_flags arch/x86/include/asm/irqflags.h:125 [inline]
 seqcount_lockdep_reader_access+0x16d/0x1d0 include/linux/seqlock.h:101
 timekeeping_get_delta kernel/time/timekeeping.c:254 [inline]
 timekeeping_get_ns kernel/time/timekeeping.c:388 [inline]
 ktime_get+0x7b/0x270 kernel/time/timekeeping.c:848
 common_hrtimer_rearm+0x5d/0x110 kernel/time/posix-timers.c:303
 posixtimer_rearm+0x131/0x340 kernel/time/posix-timers.c:329
 dequeue_signal+0x1b6/0x4b0 kernel/signal.c:704
 get_signal+0x547/0x1350 kernel/signal.c:2751
 arch_do_signal_or_restart+0xc4/0x1350 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: 0033:0x7f2551c953ee
Code: 08 0f 85 45 e1 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 90 41 57 41 56 4d 89 c6 41 55 4d 89 cd 41 54 55 53 48 83 ec 08
RSP: 002b:00007ffc6ce04fa8 EFLAGS: 00000246
RAX: fffffffffffffff7 RBX: 0000555560e743c0 RCX: 00007f2551c953ee
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000000000e
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc6ce0502c
R13: 00007f2551d30488 R14: 0000000000000000 R15: 431bde82d7b634db
 </TASK>