rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4295/1:b..l
	(detected by 1, t=10503 jiffies, g=9321, q=61)
task:kworker/u4:8    state:R  running task     stack:25952 pid: 4295 ppid:     2 flags:0x00004000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6780
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lock_acquire+0x1f2/0x3f0 kernel/locking/lockdep.c:5627
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f6 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b
RSP: 0018:ffffc90002f1f900 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 82936a7b31629e00
RDX: 0000000000000000 RSI: ffffffff8a0b2460 RDI: ffffffff8a59a740
RBP: ffffc90002f1fa20 R08: dffffc0000000000 R09: fffffbfff1ff3619
R10: fffffbfff1ff3619 R11: 1ffffffff1ff3618 R12: ffffffff8c11bfa0
R13: 1ffff920005e3f2c R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:312
 rcu_read_lock include/linux/rcupdate.h:739 [inline]
 inet_twsk_purge+0x119/0x810 net/ipv4/inet_timewait_sock.c:268
 ops_exit_list net/core/net_namespace.c:177 [inline]
 cleanup_net+0x77b/0xb80 net/core/net_namespace.c:635
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: rcu_preempt kthread starved for 10531 jiffies! g9321 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:28192 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1e0 kernel/sched/core.c:6459
 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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4647 Comm: syz.4.104 Not tainted 5.15.185-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:__unsafe_setup_sigcontext arch/x86/kernel/signal.c:168 [inline]
RIP: 0010:__setup_rt_frame arch/x86/kernel/signal.c:485 [inline]
RIP: 0010:setup_rt_frame arch/x86/kernel/signal.c:780 [inline]
RIP: 0010:handle_signal arch/x86/kernel/signal.c:824 [inline]
RIP: 0010:arch_do_signal_or_restart+0xaea/0x1300 arch/x86/kernel/signal.c:869
Code: 49 8b 06 49 89 47 48 4c 8d 73 18 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 4c 89 f7 e8 d6 df 93 00 <49> 8b 06 49 89 47 50 4c 8d 73 10 4c 89 f0 48 c1 e8 03 48 b9 00 00
RSP: 0018:ffffc9000324fcc0 EFLAGS: 00040246
RAX: 1ffff92000649fee RBX: ffffc9000324ff58 RCX: dffffc0000000000
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000324fec0 R08: 0000000000000000 R09: fffffbfff1775e66
R10: fffffbfff1775e66 R11: 1ffffffff1775e60 R12: 0000000000000000
R13: 00007f1674481d00 R14: ffffc9000324ff70 R15: 00007f1674481b38
FS:  00007f16744826c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c404a33 CR3: 0000000073588000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f167663b929
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:00007f16744820e8 EFLAGS: 00000246
RAX: fffffffffffffffc RBX: 00007f1676863088 RCX: 00007f167663b929
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f1676863088
RBP: 00007f1676863080 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f167686308c
R13: 0000000000000000 R14: 00007fff22ed9a00 R15: 00007fff22ed9ae8
 </TASK>