Re: INFO: rcu detected stall in do_softirq

[Dmitry Vyukov]

On Fri, Jan 5, 2018 at 11:14 PM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
> On Fri, Jan 5, 2018 at 11:10 PM, syzbot
> <syzbot+6a74dabfc3393d3e527f@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>> Hello,
>>
>> syzkaller hit the following crash on
>> 8a4816cad00bf14642f0ed6043b32d29a05006ce
>> git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/master
>> compiler: gcc (GCC) 7.1.1 20170620
>> .config is attached
>> Raw console output is attached.
>> Unfortunately, I don't have any reproducer for this bug yet.
>>
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+6a74dabfc3393d3e527f@xxxxxxxxxxxxxxxxxxxxxxxxx
>> It will help syzbot understand when the bug is fixed. See footer for
>> details.
>> If you forward the report, please keep this part and the footer.
>
> Looks like a hang in xfrm, so +xfrm maintainers.


#syz dup: INFO: rcu detected stall in __xfrm_decode_session


>> Can not set IPV6_FL_F_REFLECT if flowlabel_consistency sysctl is enable
>> INFO: rcu_sched detected stalls on CPUs/tasks:
>>         (detected by 0, t=125007 jiffies, g=66299, c=66298, q=40)
>> All QSes seen, last rcu_sched kthread activity 125014
>> (4294991138-4294866124), jiffies_till_next_fqs=3, root ->qsmask 0x0
>> syz-executor5   R  running task    22056 22277   3688 0x00000008
>> Call Trace:
>>  <IRQ>
>>  sched_show_task+0x4a3/0x5e0 kernel/sched/core.c:5198
>>  print_other_cpu_stall+0x996/0x1090 kernel/rcu/tree.c:1564
>>  check_cpu_stall.isra.61+0x6e6/0x15b0 kernel/rcu/tree.c:1682
>>  __rcu_pending kernel/rcu/tree.c:3440 [inline]
>>  rcu_pending kernel/rcu/tree.c:3502 [inline]
>>  rcu_check_callbacks+0x256/0xd00 kernel/rcu/tree.c:2842
>>  update_process_times+0x30/0x60 kernel/time/timer.c:1630
>>  tick_sched_handle+0x85/0x160 kernel/time/tick-sched.c:162
>>  tick_sched_timer+0x42/0x120 kernel/time/tick-sched.c:1166
>>  __run_hrtimer kernel/time/hrtimer.c:1211 [inline]
>>  __hrtimer_run_queues+0x358/0xe20 kernel/time/hrtimer.c:1275
>>  hrtimer_interrupt+0x1c2/0x5e0 kernel/time/hrtimer.c:1309
>>  local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
>>  smp_apic_timer_interrupt+0x14a/0x700 arch/x86/kernel/apic/apic.c:1050
>>  apic_timer_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:904
>> RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x50
>> RSP: 0018:ffff8801db206738 EFLAGS: 00000206 ORIG_RAX: ffffffffffffff11
>> RAX: ffffed003a2965e3 RBX: ffff8801d14b2e40 RCX: ffffffff84c25899
>> RDX: 0000000000000100 RSI: ffff8801c5f47f29 RDI: 00000000000079c8
>> RBP: ffff8801db2067c8 R08: ffffed0038bea003 R09: ffffed0038bea003
>> R10: 000000000000000b R11: ffffed0038bea002 R12: ffff8801c5f40580
>> R13: ffff8801db206aa0 R14: 00000000000079d0 R15: dffffc0000000000
>>  __xfrm_decode_session+0x68/0x110 net/xfrm/xfrm_policy.c:2358
>>  __xfrm_policy_check+0x18c/0x2350 net/xfrm/xfrm_policy.c:2393
>>  __xfrm_policy_check2 include/net/xfrm.h:1170 [inline]
>>  xfrm_policy_check include/net/xfrm.h:1175 [inline]
>>  xfrm6_policy_check include/net/xfrm.h:1185 [inline]
>>  rawv6_rcv+0x8f6/0x1200 net/ipv6/raw.c:424
>>  ipv6_raw_deliver net/ipv6/raw.c:224 [inline]
>>  raw6_local_deliver+0x819/0xa80 net/ipv6/raw.c:240
>>  ip6_input_finish+0x3c7/0x17a0 net/ipv6/ip6_input.c:246
>>  NF_HOOK include/linux/netfilter.h:250 [inline]
>>  ip6_input+0xe9/0x560 net/ipv6/ip6_input.c:327
>>  dst_input include/net/dst.h:449 [inline]
>>  ip6_rcv_finish+0x1a9/0x7a0 net/ipv6/ip6_input.c:71
>>  NF_HOOK include/linux/netfilter.h:250 [inline]
>>  ipv6_rcv+0xf37/0x1fa0 net/ipv6/ip6_input.c:208
>>  __netif_receive_skb_core+0x1a41/0x3460 net/core/dev.c:4499
>>  __netif_receive_skb+0x2c/0x1b0 net/core/dev.c:4564
>>  process_backlog+0x203/0x740 net/core/dev.c:5244
>>  napi_poll net/core/dev.c:5642 [inline]
>>  net_rx_action+0x792/0x1910 net/core/dev.c:5708
>>  __do_softirq+0x2d7/0xb85 kernel/softirq.c:285
>>  do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1115
>>  </IRQ>
>>  do_softirq.part.21+0x14d/0x190 kernel/softirq.c:329
>>  do_softirq kernel/softirq.c:177 [inline]
>>  __local_bh_enable_ip+0x1ee/0x230 kernel/softirq.c:182
>>  local_bh_enable include/linux/bottom_half.h:32 [inline]
>>  rcu_read_unlock_bh include/linux/rcupdate.h:727 [inline]
>>  ip6_finish_output2+0xba0/0x23a0 net/ipv6/ip6_output.c:121
>>  ip6_fragment+0x25f2/0x3470 net/ipv6/ip6_output.c:739
>>  ip6_finish_output+0x6bb/0xaf0 net/ipv6/ip6_output.c:152
>>  NF_HOOK_COND include/linux/netfilter.h:239 [inline]
>>  ip6_output+0x1eb/0x840 net/ipv6/ip6_output.c:171
>>  dst_output include/net/dst.h:443 [inline]
>>  ip6_local_out+0x95/0x160 net/ipv6/output_core.c:176
>>  ip6_send_skb+0xa1/0x330 net/ipv6/ip6_output.c:1674
>>  ip6_push_pending_frames+0xb3/0xe0 net/ipv6/ip6_output.c:1694
>>  rawv6_push_pending_frames net/ipv6/raw.c:616 [inline]
>>  rawv6_sendmsg+0x2ee9/0x3e70 net/ipv6/raw.c:935
>>  inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:764
>>  sock_sendmsg_nosec net/socket.c:628 [inline]
>>  sock_sendmsg+0xca/0x110 net/socket.c:638
>>  SYSC_sendto+0x361/0x5c0 net/socket.c:1719
>>  SyS_sendto+0x40/0x50 net/socket.c:1687
>>  entry_SYSCALL_64_fastpath+0x23/0x9a
>> RIP: 0033:0x452ac9
>> RSP: 002b:00007f042a550c58 EFLAGS: 00000212 ORIG_RAX: 000000000000002c
>> RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452ac9
>> RDX: 0000000000000000 RSI: 0000000020aa7000 RDI: 0000000000000013
>> RBP: 00000000000004b6 R08: 00000000201e0000 R09: 000000000000001c
>> R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f51b0
>> R13: 00000000ffffffff R14: 00007f042a5516d4 R15: 0000000000000000
>> rcu_sched kthread starved for 126236 jiffies! g66299 c66298 f0x2
>> RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=0
>> rcu_sched       R  running task    23456     8      2 0x80000000
>> Call Trace:
>>  context_switch kernel/sched/core.c:2799 [inline]
>>  __schedule+0x8eb/0x2060 kernel/sched/core.c:3375
>>  schedule+0xf5/0x430 kernel/sched/core.c:3434
>>  schedule_timeout+0x118/0x230 kernel/time/timer.c:1795
>>  rcu_gp_kthread+0x9e5/0x1930 kernel/rcu/tree.c:2314
>>  kthread+0x33c/0x400 kernel/kthread.c:238
>>  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:515