rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (10499 ticks this GP) idle=72d4/1/0x4000000000000000 softirq=53945/53945 fqs=6
	(t=10500 jiffies g=78869 q=500 ncpus=2)
rcu: rcu_preempt kthread starved for 10475 jiffies! g78869 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:27280 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5257 [inline]
 __schedule+0x1089/0x4140 kernel/sched/core.c:6584
 schedule+0xb9/0x180 kernel/sched/core.c:6660
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x303/0x13a0 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x9a/0x400 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: 15650 Comm: syz.0.3505 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
RIP: 0010:check_preemption_disabled+0x1/0x110 lib/smp_processor_id.c:13
Code: 40 a0 bc 8d 4c 89 f6 e8 9d 4d 01 fa e9 6e ff ff ff 00 00 cc cc 00 00 cc cc 48 c7 c7 40 72 fe 8a 48 c7 c6 80 72 fe 8a eb 00 55 <41> 57 41 56 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24
RSP: 0018:ffffc90000006cb0 EFLAGS: 00000007
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff81649c90
RDX: 0000000000000000 RSI: ffffffff8afe7280 RDI: ffffffff8afe7240
RBP: ffffc90000006df0 R08: ffffffff8f22416f R09: 1ffffffff1e4482d
R10: dffffc0000000000 R11: fffffbfff1e4482e R12: 1ffff92000000da8
R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffff92000000da8
FS:  00007f5fe281a6c0(0000) GS:ffff8880b8c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b35014ff8 CR3: 000000003b703000 CR4: 00000000003506f0
DR0: 0000200000000f40 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 rcu_dynticks_curr_cpu_in_eqs include/linux/context_tracking.h:122 [inline]
 rcu_is_watching+0x11/0xa0 kernel/rcu/tree.c:721
 trace_lock_release include/trace/events/lock.h:69 [inline]
 lock_release+0xcf/0x920 kernel/locking/lockdep.c:5801
 rcu_lock_release include/linux/rcupdate.h:355 [inline]
 rcu_read_unlock include/linux/rcupdate.h:824 [inline]
 __perf_event_output kernel/events/core.c:7732 [inline]
 perf_event_output_forward+0x282/0x2f0 kernel/events/core.c:7741
 __perf_event_overflow+0x457/0x630 kernel/events/core.c:9487
 perf_event_overflow kernel/events/core.c:9508 [inline]
 perf_swevent_hrtimer+0x472/0x630 kernel/events/core.c:10958
 __run_hrtimer kernel/time/hrtimer.c:1751 [inline]
 __hrtimer_run_queues+0x4e7/0xc90 kernel/time/hrtimer.c:1815
 hrtimer_interrupt+0x399/0x980 kernel/time/hrtimer.c:1877
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
 __sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1118
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:unwind_next_frame+0xac/0x1fd0 arch/x86/kernel/unwind_orc.c:436
Code: 68 4c 89 64 24 48 4c 89 7c 24 10 bf 01 00 00 00 e8 e9 c5 1f 00 4c 8d 7b 50 4c 89 f8 48 c1 e8 03 48 89 44 24 30 42 80 3c 30 00 <74> 08 4c 89 ff e8 1a c1 9a 00 4d 8b 37 4d 85 f6 74 30 49 81 c6 88
RSP: 0018:ffffc90000007540 EFLAGS: 00000246
RAX: 1ffff92000000ec7 RBX: ffffc900000075e8 RCX: ffffffff97c69103
RDX: dffffc0000000000 RSI: ffffffff88836795 RDI: 0000000000000001
RBP: 1ffff92000000ec4 R08: ffffc900000076b0 R09: 0000000000000012
R10: dffffc0000000000 R11: fffff52000000ec9 R12: ffffffff88836795
R13: ffffc900061bea80 R14: dffffc0000000000 R15: ffffc90000007638
 arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1735 [inline]
 slab_free_freelist_hook+0x133/0x1b0 mm/slub.c:1761
 slab_free mm/slub.c:3694 [inline]
 kmem_cache_free+0xf7/0x2a0 mm/slub.c:3716
 tcp_write_queue_purge+0x13c/0x300 net/ipv4/tcp.c:3123
 tcp_done_with_error+0x3f/0xc0 net/ipv4/tcp_input.c:4444
 tcp_write_err net/ipv4/tcp_timer.c:70 [inline]
 tcp_write_timeout net/ipv4/tcp_timer.c:273 [inline]
 tcp_retransmit_timer+0x1299/0x27c0 net/ipv4/tcp_timer.c:547
 tcp_write_timer+0x126/0x280 net/ipv4/tcp_timer.c:676
 call_timer_fn+0x1ac/0x670 kernel/time/timer.c:1701
 expire_timers kernel/time/timer.c:1752 [inline]
 __run_timers+0x56c/0x810 kernel/time/timer.c:2023
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2036
 handle_softirqs+0x291/0x910 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:queue_work_on+0x1a0/0x1f0 kernel/workqueue.c:1553
Code: 4d 85 e4 75 16 e8 a0 31 2e 00 eb 15 e8 99 31 2e 00 e8 04 21 e3 08 4d 85 e4 74 ea e8 8a 31 2e 00 fb 48 c7 44 24 20 0e 36 e0 45 <48> b8 00 00 00 00 00 fc ff df 49 c7 44 05 00 00 00 00 00 41 c7 44
RSP: 0018:ffffc900061be9a0 EFLAGS: 00000287
RAX: ffffffff81543716 RBX: 0000000000000000 RCX: 0000000000080000
RDX: ffffc90016d32000 RSI: 000000000002c1a5 RDI: 000000000002c1a6
RBP: ffffc900061bea70 R08: ffffffff91b6224f R09: 1ffffffff236c449
R10: dffffc0000000000 R11: fffffbfff236c44a R12: 0000000000000200
R13: 1ffff92000c37d38 R14: 0000000000000000 R15: ffffc900061beb01
 queue_work include/linux/workqueue.h:515 [inline]
 schedule_work include/linux/workqueue.h:576 [inline]
 nf_nat_masq_schedule+0x465/0x560 net/netfilter/nf_nat_masquerade.c:130
 masq_inet6_event+0xe9/0x130 net/netfilter/nf_nat_masquerade.c:295
 notifier_call_chain kernel/notifier.c:87 [inline]
 atomic_notifier_call_chain+0x17a/0x2b0 kernel/notifier.c:225
 addrconf_ifdown+0xe94/0x1a30 net/ipv6/addrconf.c:3938
 addrconf_notify+0x405/0xf60 net/ipv6/addrconf.c:-1
 notifier_call_chain kernel/notifier.c:87 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:455
 call_netdevice_notifiers_extack net/core/dev.c:2052 [inline]
 call_netdevice_notifiers net/core/dev.c:2066 [inline]
 dev_close_many+0x2a2/0x400 net/core/dev.c:1614
 unregister_netdevice_many_notify+0x497/0x1990 net/core/dev.c:11021
 rtnl_delete_link net/core/rtnetlink.c:3187 [inline]
 rtnl_dellink+0x55d/0x830 net/core/rtnetlink.c:3239
 rtnetlink_rcv_msg+0x863/0xfb0 net/core/rtnetlink.c:6166
 netlink_rcv_skb+0x1ef/0x440 net/netlink/af_netlink.c:2516
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x7ad/0x920 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1877
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x5ed/0x9a0 net/socket.c:2519
 ___sys_sendmsg+0x2a2/0x360 net/socket.c:2573
 __sys_sendmsg net/socket.c:2602 [inline]
 __do_sys_sendmsg net/socket.c:2611 [inline]
 __se_sys_sendmsg+0x1c3/0x2b0 net/socket.c:2609
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f5fe199fb19
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5fe281a028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f5fe1c25fa0 RCX: 00007f5fe199fb19
RDX: 0000000000040000 RSI: 0000200000000140 RDI: 000000000000000b
RBP: 00007f5fe1a37b70 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5fe1c26038 R14: 00007f5fe1c25fa0 R15: 00007fffb02f4978
 </TASK>
CPU: 1 PID: 15641 Comm: syz.3.3504 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 9f 64 17 f7 65 8b 05 30 01 c1 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc900001e0800 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a06 RCX: 548ce1493b65a100
RDX: dffffc0000000000 RSI: ffffffff8aac1cc0 RDI: 0000000000000001
RBP: ffffc900001e0888 R08: ffffffff91b62307 R09: 1ffffffff236c460
R10: dffffc0000000000 R11: fffffbfff236c461 R12: dffffc0000000000
R13: ffff888038650000 R14: ffffffff97efcb30 R15: 1ffff9200003c100
FS:  00007fbb2e65e6c0(0000) GS:ffff8880b8d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000231000 CR3: 0000000051de5000 CR4: 00000000003506e0
DR0: 0000200000001b80 DR1: 0000000000000000 DR2: 0000200000000740
DR3: 0000200000000740 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 __debug_check_no_obj_freed lib/debugobjects.c:1054 [inline]
 debug_check_no_obj_freed+0x471/0x520 lib/debugobjects.c:1075
 free_pages_prepare mm/page_alloc.c:1493 [inline]
 free_pcp_prepare mm/page_alloc.c:1537 [inline]
 free_unref_page_prepare+0x2c3/0x9e0 mm/page_alloc.c:3414
 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3509
 __skb_frag_unref include/linux/skbuff.h:3509 [inline]
 skb_release_data+0x4a7/0x7e0 net/core/skbuff.c:785
 skb_release_all net/core/skbuff.c:856 [inline]
 __kfree_skb+0x4c/0x60 net/core/skbuff.c:870
 tcp_write_queue_purge+0x13c/0x300 net/ipv4/tcp.c:3123
 tcp_done_with_error+0x3f/0xc0 net/ipv4/tcp_input.c:4444
 tcp_write_err net/ipv4/tcp_timer.c:70 [inline]
 tcp_write_timeout net/ipv4/tcp_timer.c:273 [inline]
 tcp_retransmit_timer+0x1299/0x27c0 net/ipv4/tcp_timer.c:547
 tcp_write_timer+0x126/0x280 net/ipv4/tcp_timer.c:676
 call_timer_fn+0x1ac/0x670 kernel/time/timer.c:1701
 expire_timers kernel/time/timer.c:1752 [inline]
 __run_timers+0x56c/0x810 kernel/time/timer.c:2023
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2036
 handle_softirqs+0x291/0x910 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:preempt_schedule_irq+0xb6/0x160 kernel/sched/core.c:6896
Code: 00 00 43 c6 44 37 04 f8 74 0b 0f 0b 48 f7 03 08 00 00 00 74 7f bf 01 00 00 00 e8 c5 d5 18 f7 e8 e0 df 48 f7 fb bf 01 00 00 00 <e8> 15 b9 ff ff 43 c6 44 37 08 00 48 c7 44 24 40 00 00 00 00 9c 8f
RSP: 0018:ffffc9000572f1a0 EFLAGS: 00000286
RAX: 548ce1493b65a100 RBX: 0000000000000000 RCX: 548ce1493b65a100
RDX: dffffc0000000000 RSI: ffffffff8aac1cc0 RDI: 0000000000000001
RBP: ffffc9000572f250 R08: ffffffff91b62277 R09: 1ffffffff236c44e
R10: dffffc0000000000 R11: fffffbfff236c44f R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffff92000ae5e34
 irqentry_exit+0x63/0x70 kernel/entry/common.c:442
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:lock_is_held_type+0x13a/0x190 kernel/locking/lockdep.c:5866
Code: 75 40 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 46 41 f7 c5 00 02 00 00 74 01 fb 65 48 8b 04 25 28 00 00 00 <48> 3b 44 24 08 75 3c 89 e8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffffc9000572f318 EFLAGS: 00000206
RAX: 548ce1493b65a100 RBX: ffff88807610bc00 RCX: 548ce1493b65a100
RDX: ffff88807610bc00 RSI: ffffffff8aac2e40 RDI: ffffffff8afe72a0
RBP: 0000000000000001 R08: dffffc0000000000 R09: 1ffffffff236c44e
R10: dffffc0000000000 R11: fffffbfff236c44f R12: 0000000000000001
R13: 0000000000000246 R14: ffff88801e77d3d8 R15: ffff88807610c708
 lock_is_held include/linux/lockdep.h:288 [inline]
 mmap_assert_locked include/linux/mmap_lock.h:155 [inline]
 find_vma+0xaf/0x1b0 mm/mmap.c:1905
 lock_mm_and_find_vma+0x71/0x2f0 mm/memory.c:5385
 do_user_addr_fault+0x2ee/0xbb0 arch/x86/mm/fault.c:1310
 handle_page_fault arch/x86/mm/fault.c:1429 [inline]
 exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1482
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0010:copy_user_enhanced_fast_string+0xa/0x40 arch/x86/lib/copy_user_64.S:166
Code: ff c9 75 f2 89 d1 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 31 c0 0f 01 ca c3 8d 0c ca 89 ca eb 20 0f 01 cb 83 fa 40 72 38 89 d1 <f3> a4 31 c0 0f 01 ca c3 89 ca eb 0a 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000572f5e8 EFLAGS: 00050206
RAX: ffffffff840eeb01 RBX: 0000000000006a14 RCX: 00000000000000bc
RDX: 0000000000006a14 RSI: 0000200000231000 RDI: ffff88803473ff44
RBP: 0000000000000000 R08: ffff88803473ffff R09: 1ffff110068e7fff
R10: dffffc0000000000 R11: ffffed10068e8000 R12: 00007fffffff85ec
R13: 00000000002295e8 R14: 000020000022a6a8 R15: ffff8880347395ec
 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline]
 raw_copy_from_user arch/x86/include/asm/uaccess_64.h:52 [inline]
 copyin+0xe7/0x120 lib/iov_iter.c:183
 _copy_from_iter+0x447/0x1130 lib/iov_iter.c:632
 copy_from_iter include/linux/uio.h:187 [inline]
 copy_from_iter_full include/linux/uio.h:194 [inline]
 skb_do_copy_data_nocache include/net/sock.h:2379 [inline]
 skb_copy_to_page_nocache include/net/sock.h:2405 [inline]
 tcp_sendmsg_locked+0x184a/0x3a30 net/ipv4/tcp.c:1387
 tcp_sendmsg+0x2b/0x40 net/ipv4/tcp.c:1494
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x5ed/0x9a0 net/socket.c:2519
 ___sys_sendmsg+0x2a2/0x360 net/socket.c:2573
 __sys_sendmsg net/socket.c:2602 [inline]
 __do_sys_sendmsg net/socket.c:2611 [inline]
 __se_sys_sendmsg+0x1c3/0x2b0 net/socket.c:2609
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fbb2d79fb19
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fbb2e65e028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fbb2da25fa0 RCX: 00007fbb2d79fb19
RDX: 00000000000052cc RSI: 0000200000001040 RDI: 0000000000000007
RBP: 00007fbb2d837b70 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbb2da26038 R14: 00007fbb2da25fa0 R15: 00007fffc3e26e38
 </TASK>