syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6799/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=29453, q=516 ncpus=2)
task:syz-executor    state:R  running task     stack:19376 pid:6799  tgid:6799  ppid:6795   flags:0x00000000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5408 [inline]
 __schedule+0x1796/0x49d0 kernel/sched/core.c:6745
 preempt_schedule_irq+0xfb/0x1c0 kernel/sched/core.c:7067
 irqentry_exit+0x5e/0x90 kernel/entry/common.c:354
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_acquire+0x264/0x550 kernel/locking/lockdep.c:5758
Code: 2b 00 74 08 4c 89 f7 e8 fa 29 86 00 f6 44 24 61 02 0f 85 85 01 00 00 41 f7 c7 00 02 00 00 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 25 00 00 00 00 00 43 c7 44 25 09 00 00 00 00 43 c7 44 25
RSP: 0018:ffffc9000467ea40 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 1ffff920008cfd54 RCX: 0000000000000001
RDX: dffffc0000000000 RSI: ffffffff8bcaccc0 RDI: ffffffff8c1f1580
RBP: ffffc9000467eb98 R08: ffffffff92f71587 R09: 1ffffffff25ee2b0
R10: dffffc0000000000 R11: fffffbfff25ee2b1 R12: 1ffff920008cfd50
R13: dffffc0000000000 R14: ffffc9000467eaa0 R15: 0000000000000246
 rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 rcu_read_lock include/linux/rcupdate.h:781 [inline]
 in6_dev_get+0x39/0x290 include/net/addrconf.h:369
 fib6_nh_init+0x1ee/0x2180 net/ipv6/route.c:3549
 ip6_route_info_create+0x99e/0x12b0 net/ipv6/route.c:3811
 addrconf_f6i_alloc+0x3c2/0x7f0 net/ipv6/route.c:4590
 ipv6_add_addr+0x5b6/0x1090 net/ipv6/addrconf.c:1120
 inet6_addr_add+0x563/0xb00 net/ipv6/addrconf.c:3059
 inet6_rtm_newaddr+0x8a3/0xc80 net/ipv6/addrconf.c:5047
 rtnetlink_rcv_msg+0x89b/0x1180 net/core/rtnetlink.c:6635
 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2564
 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
 netlink_unicast+0x7ea/0x980 net/netlink/af_netlink.c:1361
 netlink_sendmsg+0x8db/0xcb0 net/netlink/af_netlink.c:1905
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:745
 __sys_sendto+0x3a4/0x4f0 net/socket.c:2192
 __do_sys_sendto net/socket.c:2204 [inline]
 __se_sys_sendto net/socket.c:2200 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2200
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f48f1d7796c
RSP: 002b:00007ffc7fe5f6c0 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f48f2a34620 RCX: 00007f48f1d7796c
RDX: 0000000000000040 RSI: 00007f48f2a34670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffc7fe5f714 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f48f2a34670 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 10567 jiffies! g29453 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:24912 pid:17    tgid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5408 [inline]
 __schedule+0x1796/0x49d0 kernel/sched/core.c:6745
 __schedule_loop kernel/sched/core.c:6822 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6837
 schedule_timeout+0x1be/0x310 kernel/time/timer.c:2581
 rcu_gp_fqs_loop+0x2df/0x1330 kernel/rcu/tree.c:2000
 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2202
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </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:48 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:86 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt+0x21/0x30 drivers/acpi/processor_idle.c:112