syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4299/1:b..l
	(detected by 1, t=10502 jiffies, g=4969, q=276 ncpus=2)
task:syz-executor316 state:R  running task     stack:0     pid:4299  ppid:4292   flags:0x00000004
Call trace:
 __switch_to+0x2f4/0x568 arch/arm64/kernel/process.c:555
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0xdd4/0x1b2c kernel/sched/core.c:6561
 preempt_schedule_irq+0x8c/0x1b8 kernel/sched/core.c:6873
 arm64_preempt_schedule_irq+0x44/0x58 arch/arm64/kernel/entry-common.c:265
 __el1_irq arch/arm64/kernel/entry-common.c:474 [inline]
 el1_interrupt+0x3c/0x54 arch/arm64/kernel/entry-common.c:486
 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:491
 el1h_64_irq+0x64/0x68 arch/arm64/kernel/entry.S:581
 arch_local_irq_restore arch/arm64/include/asm/irqflags.h:122 [inline]
 lock_acquire+0x24c/0x644 kernel/locking/lockdep.c:5665
 rcu_lock_acquire+0x40/0x4c include/linux/rcupdate.h:350
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 net_generic+0x28/0x240 include/net/netns/generic.h:45
 xt_find_table_lock+0x4c/0x394 net/netfilter/x_tables.c:1237
 xt_request_find_table_lock+0x38/0x114 net/netfilter/x_tables.c:1284
 get_info net/ipv6/netfilter/ip6_tables.c:981 [inline]
 do_ip6t_get_ctl+0x6d0/0x1314 net/ipv6/netfilter/ip6_tables.c:1670
 nf_getsockopt+0x264/0x284 net/netfilter/nf_sockopt.c:116
 ipv6_getsockopt+0x2bc/0x3e4 net/ipv6/ipv6_sockglue.c:1512
 tcp_getsockopt+0xcc/0xe8 net/ipv4/tcp.c:4469
 sock_common_getsockopt+0xa8/0xc4 net/core/sock.c:3655
 __sys_getsockopt+0x1e0/0x480 net/socket.c:2332
 __do_sys_getsockopt net/socket.c:2347 [inline]
 __se_sys_getsockopt net/socket.c:2344 [inline]
 __arm64_sys_getsockopt+0xb8/0xd4 net/socket.c:2344
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
rcu: rcu_preempt kthread starved for 10506 jiffies! g4969 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:0     pid:16    ppid:2      flags:0x00000008
Call trace:
 __switch_to+0x2f4/0x568 arch/arm64/kernel/process.c:555
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0xdd4/0x1b2c kernel/sched/core.c:6561
 schedule+0xc4/0x170 kernel/sched/core.c:6637
 schedule_timeout+0x180/0x2c8 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2a8/0x134c kernel/rcu/tree.c:1706
 rcu_gp_kthread+0xc0/0x2f8 kernel/rcu/tree.c:1905
 kthread+0x250/0x2d8 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:864
rcu: Stack dump where RCU GP kthread last ran:
Task dump for CPU 0:
task:syz-executor316 state:R  running task     stack:0     pid:4372  ppid:4296   flags:0x00000001
Call trace:
 __switch_to+0x2f4/0x568 arch/arm64/kernel/process.c:555
 0xffff0000c9e6a61c