syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P8008/3:b..l
	(detected by 1, t=10502 jiffies, g=39317, q=27 ncpus=2)
task:syz.2.986       state:R  running task     stack:25848 pid:8008  ppid:4256   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5243 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6560
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6872
 irqentry_exit+0x53/0x80 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__sanitizer_cov_trace_switch+0x0/0xe0 kernel/kcov.c:326
Code: 39 c8 77 1e 49 ff c2 4c 89 12 48 c7 44 11 08 07 00 00 00 48 89 7c 11 10 48 89 74 11 18 4c 89 44 11 20 c3 0f 1f 80 00 00 00 00 <41> 57 41 56 41 54 53 48 8b 46 08 48 83 c0 f8 48 c1 c0 3d 48 83 f8
RSP: 0018:ffffc90006516ef0 EFLAGS: 00000297
RAX: 0000000000000002 RBX: ffff888076b98000 RCX: 0000000000080000
RDX: ffff88802f528000 RSI: ffffffff8e656dc0 RDI: 0000000000000001
RBP: 0000000000000001 R08: ffffffff896cb0df R09: fffff52000ca2e07
R10: 0000000000000000 R11: dffffc0000000001 R12: ffffc90006517040
R13: ffffc90006517080 R14: dffffc0000000000 R15: 0000000000000001
 ipv6_get_saddr_eval+0x66/0xe90 net/ipv6/addrconf.c:1558
 __ipv6_dev_get_saddr+0x1d3/0x4a0 net/ipv6/addrconf.c:1712
 ipv6_dev_get_saddr+0x417/0xbc0 net/ipv6/addrconf.c:1848
 ip6_route_get_saddr include/net/ip6_route.h:152 [inline]
 ip6_dst_lookup_tail+0xebc/0x1470 net/ipv6/ip6_output.c:1129
 ip6_dst_lookup_flow+0xb5/0x170 net/ipv6/ip6_output.c:1255
 sctp_v6_get_dst+0x955/0x1e80 net/sctp/ipv6.c:327
 sctp_transport_route+0x10c/0x2b0 net/sctp/transport.c:455
 sctp_packet_config+0x432/0xd90 net/sctp/output.c:103
 sctp_outq_select_transport+0x470/0x580 net/sctp/outqueue.c:869
 sctp_outq_flush_ctrl net/sctp/outqueue.c:903 [inline]
 sctp_outq_flush+0x4ba/0x3d70 net/sctp/outqueue.c:1212
 sctp_side_effects net/sctp/sm_sideeffect.c:1199 [inline]
 sctp_do_sm+0x55e7/0x5c80 net/sctp/sm_sideeffect.c:1170
 sctp_primitive_ASSOCIATE+0x91/0xc0 net/sctp/primitive.c:73
 __sctp_connect+0x9b7/0xe10 net/sctp/socket.c:1232
 __sctp_setsockopt_connectx net/sctp/socket.c:1334 [inline]
 sctp_getsockopt_connectx3+0x467/0x720 net/sctp/socket.c:1419
 sctp_getsockopt+0x3a0/0x7f0 net/sctp/socket.c:8125
 __sys_getsockopt+0x2b2/0x5d0 net/socket.c:2332
 __do_sys_getsockopt net/socket.c:2347 [inline]
 __se_sys_getsockopt net/socket.c:2344 [inline]
 __x64_sys_getsockopt+0xb1/0xc0 net/socket.c:2344
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f1dea18d169
RSP: 002b:00007f1deaf64038 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 00007f1dea3a5fa0 RCX: 00007f1dea18d169
RDX: 000000000000006f RSI: 0000000000000084 RDI: 0000000000000004
RBP: 00007f1dea20e2a0 R08: 00002000000002c0 R09: 0000000000000000
R10: 0000200000000280 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f1dea3a5fa0 R15: 00007ffe891ba938
 </TASK>
rcu: rcu_preempt kthread starved for 10548 jiffies! g39317 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:26712 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5243 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6560
 schedule+0xbf/0x180 kernel/sched/core.c:6636
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2d2/0x1150 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0xa3/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x28d/0x320 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 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt drivers/acpi/processor_idle.c:111 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:567