syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P9/1:b..l
rcu: 	(detected by 0, t=10503 jiffies, g=7277, q=72 ncpus=2)
task:kworker/0:1     state:R  running task     stack:27448 pid:9     ppid:2      flags:0x00004000
Workqueue: events_power_efficient gc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x14e2/0x4580 kernel/sched/core.c:6700
 preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7010
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:lock_acquire+0x1f2/0x410 kernel/locking/lockdep.c:5758
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 66 43 c7 44 3c 09 00 00 43 c6 44 3c 0b 00
RSP: 0018:ffffc900000e7940 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: c7aed6ab9775da00
RDX: 0000000000000000 RSI: ffffffff8aaac440 RDI: ffffffff8afc6780
RBP: ffffc900000e7a48 R08: dffffc0000000000 R09: 1ffffffff21b08a4
R10: dffffc0000000000 R11: fffffbfff21b08a5 R12: 1ffff9200001cf34
R13: ffffffff8cd2f760 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 rcu_read_lock include/linux/rcupdate.h:786 [inline]
 gc_worker+0x28d/0x14b0 net/netfilter/nf_conntrack_core.c:1488
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 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: rcu_preempt kthread starved for 10528 jiffies! g7277 f0x0 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:27496 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x14e2/0x4580 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_timeout+0x160/0x280 kernel/time/timer.c:2167
 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1663
 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1862
 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: 5798 Comm: syz-executor331 Not tainted 6.6.93-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:trace_irq_disable+0x30/0xe0 include/trace/events/preemptirq.h:36
Code: 8b 05 c0 bf 77 7e 83 f8 08 73 2e 89 c3 c1 e8 06 48 8d 3c c5 68 a7 49 8e be 08 00 00 00 e8 28 43 52 00 48 0f a3 1d f8 ac bd 0c <73> 09 e8 99 95 e3 ff 84 c0 74 08 5b 41 5e c3 0f 0b eb ce 0f 0b eb
RSP: 0018:ffffc9000482fa88 EFLAGS: 00000057
RAX: 0000000000000001 RBX: 0000000000000001 RCX: ffffffff818bfa68
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8e49a768
RBP: ffffc9000482fb30 R08: ffffffff8e49a76f R09: 1ffffffff1c934ed
R10: dffffc0000000000 R11: fffffbfff1c934ee R12: ffffffff8131483e
R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffff92000905f54
FS:  0000555573f123c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000006b000 CR3: 0000000020d77000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __local_bh_enable_ip+0xcf/0x1c0 kernel/softirq.c:388
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 fpregs_unlock arch/x86/include/asm/fpu/api.h:80 [inline]
 restore_fpregs_from_user arch/x86/kernel/fpu/signal.c:331 [inline]
 __fpu_restore_sig arch/x86/kernel/fpu/signal.c:359 [inline]
 fpu__restore_sig+0x920/0x10e0 arch/x86/kernel/fpu/signal.c:493
 restore_sigcontext arch/x86/kernel/signal_64.c:95 [inline]
 __ia32_sys_rt_sigreturn+0x65d/0x7b0 arch/x86/kernel/signal_64.c:266
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f745abaa91a
Code: 48 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c 24 0c e8 e3 6a 02 00 8b 7c 24 0c 89 c2 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 36 89 d7 89 44 24 0c e8 43 6b 02 00 8b 44 24
RSP: 002b:00007fff6ab2a9d0 EFLAGS: 00000293
RAX: fffffffffffffff7 RBX: 0000000000000007 RCX: 00007f745abaa91a
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 0000000000000000 R08: 00007f745ab6b990 R09: 00007f745ab6b990
R10: 0000000000000000 R11: 0000000000000293 R12: 00007f745ac0933c
R13: 00007f745ac03106 R14: 00007fff6ab2aa20 R15: 0000000000000000
 </TASK>