BUG: soft lockup in tcp_write_timer

Status: auto-closed as invalid on 2020/09/05 12:42
Reported-by: syzbot+e48013d86223d2ce3c18@syzkaller.appspotmail.com
First crash: 2364d, last: 2285d
▶ ▼ Similar bugs (18)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream BUG: soft lockup in tcp_write_timer (10) perf mm net 1 3 151d 181d 0/29 closed as invalid on 2026/03/27 01:43
linux-4.19 BUG: soft lockup in tcp_write_timer (3) 1 2 1318d 1332d 0/1 upstream: reported on 2022/12/17 21:41
linux-4.19 BUG: soft lockup in tcp_write_timer (2) 1 2 1728d 1792d 0/1 auto-closed as invalid on 2022/03/16 10:56
linux-5.15 INFO: rcu detected stall in tcp_write_timer 1 4 665d 718d 0/3 auto-obsoleted due to no activity on 2025/01/22 08:13
android-54 BUG: soft lockup in tcp_write_timer 1 1 464d 464d 0/2 auto-obsoleted due to no activity on 2025/08/01 21:51
linux-4.19 BUG: soft lockup in tcp_write_timer 1 1 1957d 1957d 0/1 auto-closed as invalid on 2021/07/30 14:52
upstream BUG: soft lockup in tcp_write_timer (9) net 1 2 245d 249d 0/29 closed as invalid on 2026/01/07 12:42
upstream BUG: soft lockup in tcp_write_timer net 1 11 2564d 2572d 0/29 auto-closed as invalid on 2019/10/25 14:11
upstream BUG: soft lockup in tcp_write_timer (4) mm 1 4 765d 790d 26/29 fixed on 2024/07/09 19:14
upstream BUG: soft lockup in tcp_write_timer (2) kvm 1 1 1567d 1567d 0/29 auto-closed as invalid on 2022/06/24 22:31
linux-5.15 INFO: rcu detected stall in tcp_write_timer (4) origin:lts-only 1 syz error 4 81d 162d 0/3 upstream: reported syz repro on 2026/03/01 05:59
upstream BUG: soft lockup in tcp_write_timer (3) net 1 6 945d 1052d 0/29 closed as invalid on 2024/03/18 17:07
linux-6.6 INFO: rcu detected stall in tcp_write_timer 1 5 23d 153d 0/2 upstream: reported on 2026/03/10 11:19
upstream BUG: soft lockup in tcp_write_timer (7) net 1 1 330d 330d 0/29 closed as invalid on 2025/09/29 07:16
upstream BUG: soft lockup in tcp_write_timer (8) mm 1 1 306d 306d 0/29 closed as invalid on 2025/11/04 11:28
upstream BUG: soft lockup in tcp_write_timer (6) bpf 1 1 378d 378d 0/29 closed as invalid on 2025/09/01 08:24
upstream BUG: soft lockup in tcp_write_timer (5) mm net 1 8 434d 496d 0/29 closed as invalid on 2025/07/11 15:27
android-5-15 BUG: soft lockup in tcp_write_timer 1 11 728d 841d 0/2 auto-obsoleted due to no activity on 2024/11/10 05:27

Sample crash report:
ip6_tables: ip6tables: counters copy to user failed while replacing table
ip6_tables: ip6tables: counters copy to user failed while replacing table
watchdog: BUG: soft lockup - CPU#0 stuck for 123s! [swapper/0:0]
Modules linked in:
irq event stamp: 20434323
hardirqs last  enabled at (20434322): [<ffffffff86600972>] restore_regs_and_return_to_kernel+0x0/0x2e
hardirqs last disabled at (20434323): [<ffffffff86601aba>] apic_timer_interrupt+0x8a/0xa0 arch/x86/entry/entry_64.S:792
softirqs last  enabled at (20404574): [<ffffffff81374d4d>] irq_enter+0xbd/0xd0 kernel/softirq.c:350
softirqs last disabled at (20404575): [<ffffffff81374ebb>] invoke_softirq kernel/softirq.c:368 [inline]
softirqs last disabled at (20404575): [<ffffffff81374ebb>] irq_exit+0x15b/0x1a0 kernel/softirq.c:409
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.14.179-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff87c76240 task.stack: ffffffff87c00000
RIP: 0010:__sanitizer_cov_trace_pc+0x28/0x50 kernel/kcov.c:93
RSP: 0018:ffff8880aea06dd8 EFLAGS: 00000206 ORIG_RAX: ffffffffffffff10
RAX: ffffffff87c76240 RBX: 000000000000007f RCX: 0000000000001bc8
RDX: 0000000000000100 RSI: 0000000000000003 RDI: 0000000000000000
RBP: ffff888177fc7862 R08: 0000000000000043 R09: ffffffff8a05fa58
R10: ffffffff87c76c30 R11: ffffffff87c76240 R12: ffff888056d28b80
R13: 0000000000000003 R14: ffff888177fc7848 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000564575c4b920 CR3: 0000000007c6a000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 sfq_dequeue+0x125/0xdb0 net/sched/sch_sfq.c:497
 dequeue_skb net/sched/sch_generic.c:148 [inline]
 qdisc_restart net/sched/sch_generic.c:241 [inline]
 __qdisc_run+0x2b7/0xde0 net/sched/sch_generic.c:257
 __dev_xmit_skb net/core/dev.c:3223 [inline]
 __dev_queue_xmit+0x1b9b/0x25c0 net/core/dev.c:3493
 neigh_hh_output include/net/neighbour.h:490 [inline]
 neigh_output include/net/neighbour.h:498 [inline]
 ip_finish_output2+0xde8/0x14a0 net/ipv4/ip_output.c:229
 ip_finish_output+0x556/0xc30 net/ipv4/ip_output.c:317
 NF_HOOK_COND include/linux/netfilter.h:239 [inline]
 ip_output+0x1c2/0x520 net/ipv4/ip_output.c:405
 dst_output include/net/dst.h:462 [inline]
 ip_local_out+0x93/0x170 net/ipv4/ip_output.c:124
 ip_send_skb+0x3a/0xc0 net/ipv4/ip_output.c:1422
 ip_push_pending_frames+0x5f/0x80 net/ipv4/ip_output.c:1442
 icmp_push_reply+0x381/0x4f0 net/ipv4/icmp.c:395
 __icmp_send+0x90f/0x1110 net/ipv4/icmp.c:743
 ipv4_send_dest_unreach net/ipv4/route.c:1222 [inline]
 ipv4_link_failure+0x417/0x790 net/ipv4/route.c:1229
 dst_link_failure include/net/dst.h:445 [inline]
 vti_xmit net/ipv4/ip_vti.c:304 [inline]
 vti_tunnel_xmit+0x3fc/0x16c0 net/ipv4/ip_vti.c:339
 __netdev_start_xmit include/linux/netdevice.h:4039 [inline]
 netdev_start_xmit include/linux/netdevice.h:4048 [inline]
 xmit_one net/core/dev.c:3009 [inline]
 dev_hard_start_xmit+0x186/0x890 net/core/dev.c:3025
 __dev_queue_xmit+0x1d91/0x25c0 net/core/dev.c:3525
 neigh_output include/net/neighbour.h:500 [inline]
 ip_finish_output2+0x766/0x14a0 net/ipv4/ip_output.c:229
 ip_finish_output+0x556/0xc30 net/ipv4/ip_output.c:317
 NF_HOOK_COND include/linux/netfilter.h:239 [inline]
 ip_output+0x1c2/0x520 net/ipv4/ip_output.c:405
 dst_output include/net/dst.h:462 [inline]
 ip_local_out+0x93/0x170 net/ipv4/ip_output.c:124
 ip_queue_xmit+0x7b2/0x1b20 net/ipv4/ip_output.c:504
 __tcp_transmit_skb+0x1654/0x2dd0 net/ipv4/tcp_output.c:1131
 tcp_transmit_skb net/ipv4/tcp_output.c:1147 [inline]
 __tcp_retransmit_skb+0x52b/0x1b20 net/ipv4/tcp_output.c:2938
 tcp_retransmit_skb+0x28/0x220 net/ipv4/tcp_output.c:2952
 tcp_retransmit_timer+0x97e/0x2540 net/ipv4/tcp_timer.c:498
 tcp_write_timer_handler+0x44f/0x7b0 net/ipv4/tcp_timer.c:583
 tcp_write_timer+0xc7/0x160 net/ipv4/tcp_timer.c:601
 call_timer_fn+0x14a/0x650 kernel/time/timer.c:1279
 expire_timers kernel/time/timer.c:1318 [inline]
 __run_timers kernel/time/timer.c:1636 [inline]
 __run_timers kernel/time/timer.c:1604 [inline]
 run_timer_softirq+0x52a/0x1390 kernel/time/timer.c:1649
 __do_softirq+0x254/0x9bf kernel/softirq.c:288
 invoke_softirq kernel/softirq.c:368 [inline]
 irq_exit+0x15b/0x1a0 kernel/softirq.c:409
 exiting_irq arch/x86/include/asm/apic.h:648 [inline]
 smp_apic_timer_interrupt+0x141/0x5e0 arch/x86/kernel/apic/apic.c:1102
 apic_timer_interrupt+0x8f/0xa0 arch/x86/entry/entry_64.S:792
 </IRQ>
RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61
RSP: 0018:ffffffff87c07e78 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff10
RAX: 1ffffffff0fa2cd4 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000001 RDI: ffffffff87c76ac4
RBP: ffffffff87d16690 R08: 1ffffffff1124201 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: fffffbfff0f8ec48
R13: ffffffff87c76240 R14: 0000000000000000 R15: 0000000000000000
 arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline]
 default_idle+0x47/0x370 arch/x86/kernel/process.c:566
 cpuidle_idle_call kernel/sched/idle.c:156 [inline]
 do_idle+0x250/0x3c0 kernel/sched/idle.c:246
 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:351
 start_kernel+0x659/0x676 init/main.c:708
 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240
Code: ff ff 90 65 48 8b 04 25 40 ee 01 00 48 85 c0 74 1a 65 8b 15 fb a7 a7 7e 81 e2 00 01 1f 00 75 0b 8b 90 58 13 00 00 83 fa 01 74 01 <c3> 48 8b 34 24 48 8b 88 60 13 00 00 8b 80 5c 13 00 00 48 8b 11 
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.14.179-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8880a988c340 task.stack: ffff8880a9898000
RIP: 0010:__read_once_size include/linux/compiler.h:183 [inline]
RIP: 0010:trylock_clear_pending kernel/locking/qspinlock_paravirt.h:99 [inline]
RIP: 0010:pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:412 [inline]
RIP: 0010:__pv_queued_spin_lock_slowpath+0x270/0x950 kernel/locking/qspinlock.c:465
RSP: 0018:ffff8880aeb06f20 EFLAGS: 00000206
RAX: 0000000000000000 RBX: ffff8880aeb2c0c0 RCX: ffffed100ada5184
RDX: 0000000000004d35 RSI: 0000000000000001 RDI: 0000000000000286
RBP: ffff888056d28c20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff888056d28c21 R15: ffffed1015d65820
FS:  0000000000000000(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000564575c4b920 CR3: 0000000081efb000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:669 [inline]
 queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:52 [inline]
 queued_spin_lock include/asm-generic/qspinlock.h:90 [inline]
 do_raw_spin_lock+0x189/0x230 kernel/locking/spinlock_debug.c:113
 spin_lock include/linux/spinlock.h:317 [inline]
 __dev_xmit_skb net/core/dev.c:3204 [inline]
 __dev_queue_xmit+0x11c2/0x25c0 net/core/dev.c:3493
 neigh_hh_output include/net/neighbour.h:490 [inline]
 neigh_output include/net/neighbour.h:498 [inline]
 ip_finish_output2+0xde8/0x14a0 net/ipv4/ip_output.c:229
 ip_finish_output+0x556/0xc30 net/ipv4/ip_output.c:317
 NF_HOOK_COND include/linux/netfilter.h:239 [inline]
 ip_output+0x1c2/0x520 net/ipv4/ip_output.c:405
 dst_output include/net/dst.h:462 [inline]
 ip_local_out+0x93/0x170 net/ipv4/ip_output.c:124
 iptunnel_xmit+0x583/0x970 net/ipv4/ip_tunnel_core.c:91
 ip_tunnel_xmit+0xf67/0x32d8 net/ipv4/ip_tunnel.c:797
 sit_tunnel_xmit__+0xa0/0x120 net/ipv6/sit.c:1008
 sit_tunnel_xmit+0x12e/0x1f6b net/ipv6/sit.c:1021
 __netdev_start_xmit include/linux/netdevice.h:4039 [inline]
 netdev_start_xmit include/linux/netdevice.h:4048 [inline]
 xmit_one net/core/dev.c:3009 [inline]
 dev_hard_start_xmit+0x186/0x890 net/core/dev.c:3025
 __dev_queue_xmit+0x1d91/0x25c0 net/core/dev.c:3525
 neigh_output include/net/neighbour.h:500 [inline]
 ip_finish_output2+0x766/0x14a0 net/ipv4/ip_output.c:229
 ip_finish_output+0x556/0xc30 net/ipv4/ip_output.c:317
 NF_HOOK_COND include/linux/netfilter.h:239 [inline]
 ip_output+0x1c2/0x520 net/ipv4/ip_output.c:405
 dst_output include/net/dst.h:462 [inline]
 ip_local_out+0x93/0x170 net/ipv4/ip_output.c:124
 ip_queue_xmit+0x7b2/0x1b20 net/ipv4/ip_output.c:504
 __tcp_transmit_skb+0x1654/0x2dd0 net/ipv4/tcp_output.c:1131
 tcp_transmit_skb net/ipv4/tcp_output.c:1147 [inline]
 __tcp_retransmit_skb+0x52b/0x1b20 net/ipv4/tcp_output.c:2938
 tcp_retransmit_skb+0x28/0x220 net/ipv4/tcp_output.c:2952
 tcp_retransmit_timer+0x97e/0x2540 net/ipv4/tcp_timer.c:498
 tcp_write_timer_handler+0x44f/0x7b0 net/ipv4/tcp_timer.c:583
 tcp_write_timer+0xc7/0x160 net/ipv4/tcp_timer.c:601
 call_timer_fn+0x14a/0x650 kernel/time/timer.c:1279
 expire_timers kernel/time/timer.c:1318 [inline]
 __run_timers kernel/time/timer.c:1636 [inline]
 __run_timers kernel/time/timer.c:1604 [inline]
 run_timer_softirq+0x52a/0x1390 kernel/time/timer.c:1649
 __do_softirq+0x254/0x9bf kernel/softirq.c:288
 invoke_softirq kernel/softirq.c:368 [inline]
 irq_exit+0x15b/0x1a0 kernel/softirq.c:409
 exiting_irq arch/x86/include/asm/apic.h:648 [inline]
 smp_apic_timer_interrupt+0x141/0x5e0 arch/x86/kernel/apic/apic.c:1102
 apic_timer_interrupt+0x8f/0xa0 arch/x86/entry/entry_64.S:792
 </IRQ>
RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61
RSP: 0018:ffff8880a989fee0 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff10
RAX: 1ffffffff0fa2cd4 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000001 RDI: ffff8880a988cbc4
RBP: ffffffff87d16690 R08: 1ffffffff1124201 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffed1015311868
R13: ffff8880a988c340 R14: 0000000000000000 R15: 0000000000000000
 arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline]
 default_idle+0x47/0x370 arch/x86/kernel/process.c:566
 cpuidle_idle_call kernel/sched/idle.c:156 [inline]
 do_idle+0x250/0x3c0 kernel/sched/idle.c:246
 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:351
 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240
Code: 89 e8 c6 45 01 01 ba 00 80 00 00 48 c1 e9 03 41 83 e0 07 be 01 00 00 00 4c 01 e9 eb 0b f3 90 83 ea 01 0f 84 6f 04 00 00 0f b6 01 <44> 38 c0 7f 08 84 c0 0f 85 78 05 00 00 0f b6 45 00 84 c0 75 dd

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/05/08 12:41 linux-4.14.y d71f695ce745 fe4122c3 .config console log report ci2-linux-4-14
2020/02/19 09:46 linux-4.14.y 98db2bf27b9e 135c18aa .config console log report ci2-linux-4-14
* Struck through repros no longer work on HEAD.