syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P24935/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=317233, q=837 ncpus=2)
task:kworker/u10:11  state:R  running task     stack:22792 pid:24935 tgid:24935 ppid:2      task_flags:0x4208160 flags:0x00080000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5387 [inline]
 __schedule+0x10e9/0x6820 kernel/sched/core.c:7188
 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7512
 irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:476 [inline]
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline]
 irqentry_exit+0x1fe/0x790 kernel/entry/common.c:164
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_acquire+0x5e/0x370 kernel/locking/lockdep.c:5872
Code: 05 bb c2 2d 12 83 f8 07 0f 87 d9 02 00 00 48 0f a3 05 86 8e f7 0e 0f 82 a4 02 00 00 8b 35 0e c2 f7 0e 85 f6 0f 85 bf 00 00 00 <48> 8b 44 24 30 65 48 2b 05 5d c2 2d 12 0f 85 ed 02 00 00 48 83 c4
RSP: 0018:ffffc9000e27f030 EFLAGS: 00000206
RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000004
RDX: 0000000000000000 RSI: ffffffff8df24d98 RDI: ffffffff8c1be660
RBP: ffffffff8e7e6ce0 R08: 0000000011b8cb06 R09: 0000000000000007
R10: 0000000000000200 R11: 0000000000000000 R12: 0000000000000002
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 rcu_read_lock include/linux/rcupdate.h:838 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1181 [inline]
 unwind_next_frame+0xd1/0x2090 arch/x86/kernel/unwind_orc.c:495
 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2689 [inline]
 slab_free mm/slub.c:6246 [inline]
 kmem_cache_free+0x127/0x6c0 mm/slub.c:6373
 kfree_skbmem+0x19a/0x210 net/core/skbuff.c:1137
 __kfree_skb net/core/skbuff.c:1204 [inline]
 consume_skb net/core/skbuff.c:1436 [inline]
 consume_skb+0xd1/0x110 net/core/skbuff.c:1430
 netlink_broadcast_filtered+0x363/0xe90 net/netlink/af_netlink.c:1535
 nlmsg_multicast_filtered include/net/netlink.h:1165 [inline]
 nlmsg_multicast include/net/netlink.h:1184 [inline]
 nlmsg_notify+0xb1/0x290 net/netlink/af_netlink.c:2593
 inet6_netconf_notify_devconf+0xf8/0x170 net/ipv6/addrconf.c:605
 __addrconf_sysctl_unregister net/ipv6/addrconf.c:7369 [inline]
 addrconf_sysctl_unregister+0x134/0x1c0 net/ipv6/addrconf.c:7393
 addrconf_ifdown.isra.0+0x1522/0x1b70 net/ipv6/addrconf.c:4018
 addrconf_notify+0x4a3/0x1ba0 net/ipv6/addrconf.c:3788
 notifier_call_chain+0x99/0x400 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x110 net/core/dev.c:2249
 call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
 call_netdevice_notifiers net/core/dev.c:2301 [inline]
 unregister_netdevice_many_notify+0x118f/0x24f0 net/core/dev.c:12464
 ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
 ops_undo_list+0x8ff/0xab0 net/core/net_namespace.c:248
 cleanup_net+0x499/0x920 net/core/net_namespace.c:702
 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3302
 process_scheduled_works kernel/workqueue.c:3385 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3466
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: rcu_preempt kthread starved for 9254 jiffies! g317233 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:28904 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5387 [inline]
 __schedule+0x10e9/0x6820 kernel/sched/core.c:7188
 __schedule_loop kernel/sched/core.c:7267 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7282
 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2095
 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2297
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63
Code: e6 8c 02 e9 83 42 03 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 23 8b 18 00 fb f4 <c3> cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffc90000197df0 EFLAGS: 00000246
RAX: 0000000000f5f41b RBX: ffff88801eaa8000 RCX: ffffffff8b930045
RDX: 0000000000000000 RSI: ffffffff8df4a1bf RDI: ffffffff8c1be660
RBP: 0000000000000000 R08: 0000000000000001 R09: ffffed10170a67ad
R10: ffff8880b8533d6b R11: 0000000000000000 R12: 0000000000000001
R13: ffffed1003d55000 R14: 0000000000000001 R15: ffffffff90dbbc10
FS:  0000000000000000(0000) GS:ffff888124401000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055cb548a8088 CR3: 000000007485e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:62 [inline]
 default_idle+0x9/0x10 arch/x86/kernel/process.c:767
 default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:199 [inline]
 do_idle+0x464/0x590 kernel/sched/idle.c:352
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:451
 start_secondary+0x21d/0x2d0 arch/x86/kernel/smpboot.c:312
 common_startup_64+0x13e/0x148
 </TASK>