BUG: soft lockup in tcp_write_timer

Status: auto-closed as invalid on 2021/07/30 14:52
Reported-by: syzbot+4300ddfa0facc43bddea@syzkaller.appspotmail.com
First crash: 1954d, last: 1954d
▶ ▼ Similar bugs (25)
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 148d 178d 0/29 closed as invalid on 2026/03/27 01:43
linux-4.19 BUG: soft lockup in tcp_write_timer (3) 1 2 1316d 1329d 0/1 upstream: reported on 2022/12/17 21:41
linux-4.14 BUG: soft lockup in tcp_write_timer 1 2 2282d 2362d 0/1 auto-closed as invalid on 2020/09/05 12:42
linux-4.19 BUG: soft lockup in tcp_write_timer (2) 1 2 1725d 1789d 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 663d 715d 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 461d 461d 0/2 auto-obsoleted due to no activity on 2025/08/01 21:51
upstream BUG: soft lockup in tcp_write_timer (9) net 1 2 243d 247d 0/29 closed as invalid on 2026/01/07 12:42
upstream BUG: soft lockup in tcp_write_timer net 1 11 2562d 2569d 0/29 auto-closed as invalid on 2019/10/25 14:11
upstream BUG: soft lockup in tcp_write_timer (4) mm 1 4 763d 787d 26/29 fixed on 2024/07/09 19:14
upstream BUG: soft lockup in tcp_write_timer (2) kvm 1 1 1565d 1565d 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 78d 160d 0/3 upstream: reported syz repro on 2026/03/01 05:59
upstream BUG: soft lockup in tcp_write_timer (3) net 1 6 942d 1050d 0/29 closed as invalid on 2024/03/18 17:07
linux-6.6 INFO: rcu detected stall in tcp_write_timer 1 5 20d 150d 0/2 upstream: reported on 2026/03/10 11:19
upstream BUG: soft lockup in tcp_write_timer (7) net 1 1 328d 328d 0/29 closed as invalid on 2025/09/29 07:16
upstream BUG: soft lockup in tcp_write_timer (8) mm 1 1 304d 304d 0/29 closed as invalid on 2025/11/04 11:28
upstream BUG: soft lockup in tcp_write_timer (6) bpf 1 1 376d 376d 0/29 closed as invalid on 2025/09/01 08:24
upstream BUG: soft lockup in tcp_write_timer (5) mm net 1 8 431d 493d 0/29 closed as invalid on 2025/07/11 15:27
android-5-15 BUG: soft lockup in tcp_write_timer 1 11 726d 838d 0/2 auto-obsoleted due to no activity on 2024/11/10 05:27
upstream INFO: rcu detected stall in tcp_write_timer (2) bpf 1 2 2012d 2068d 0/29 auto-closed as invalid on 2021/05/03 11:59
upstream INFO: rcu detected stall in tcp_write_timer (4) net 1 1 754d 754d 0/29 auto-obsoleted due to no activity on 2024/10/13 08:46
linux-5.15 INFO: rcu detected stall in tcp_write_timer (2) 1 2 448d 532d 0/3 auto-obsoleted due to no activity on 2025/08/25 02:13
upstream INFO: rcu detected stall in tcp_write_timer (3) net 1 1 1879d 1879d 0/29 auto-closed as invalid on 2021/09/13 13:17
linux-6.1 INFO: rcu detected stall in tcp_write_timer 1 16 548d 778d 0/3 auto-obsoleted due to no activity on 2025/05/16 12:07
linux-6.1 INFO: rcu detected stall in tcp_write_timer (2) 1 3 35d 155d 0/3 upstream: reported on 2026/03/06 03:16
linux-5.15 INFO: rcu detected stall in tcp_write_timer (3) 1 2 297d 313d 0/3 auto-obsoleted due to no activity on 2026/01/22 20:12

Sample crash report:
watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [syz-executor.4:14945]
Modules linked in:
irq event stamp: 3325185
hardirqs last  enabled at (3325184): [<ffffffff81003ce4>] trace_hardirqs_on_thunk+0x1a/0x1c
hardirqs last disabled at (3325185): [<ffffffff81003d00>] trace_hardirqs_off_thunk+0x1a/0x1c
softirqs last  enabled at (30858): [<ffffffff88400678>] __do_softirq+0x678/0x980 kernel/softirq.c:318
softirqs last disabled at (32063): [<ffffffff81392675>] invoke_softirq kernel/softirq.c:372 [inline]
softirqs last disabled at (32063): [<ffffffff81392675>] irq_exit+0x215/0x260 kernel/softirq.c:412
CPU: 1 PID: 14945 Comm: syz-executor.4 Not tainted 4.19.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:debug_lockdep_rcu_enabled+0x35/0xe0 kernel/rcu/update.c:253
Code: 00 00 00 00 fc ff df 48 89 c1 83 e0 07 48 c1 e9 03 83 c0 03 0f b6 14 11 38 d0 7c 08 84 d2 0f 85 87 00 00 00 8b 35 6f 64 d6 09 <85> f6 74 79 48 c7 c0 00 ea 45 8a 48 ba 00 00 00 00 00 fc ff df 48
RSP: 0018:ffff8880ba1074e0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000007 RBX: ffff88803ac3a368 RCX: 1ffffffff164dc18
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000286
RBP: 0000000021f6f5f6 R08: 0000000058abd5ee R09: 0000000000000005
R10: ffff888043cdef10 R11: 0000000000000000 R12: ffffffff895062e0
R13: dffffc0000000000 R14: ffff888045cf0100 R15: ffff8880ba107730
FS:  00007ff80caaf700(0000) GS:ffff8880ba100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd19ea63fc8 CR3: 00000000a0586000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 rcu_read_lock include/linux/rcupdate.h:628 [inline]
 __nf_conntrack_find_get+0xbf/0x1740 net/netfilter/nf_conntrack_core.c:748
 resolve_normal_ct net/netfilter/nf_conntrack_core.c:1526 [inline]
 nf_conntrack_in+0x444/0xe20 net/netfilter/nf_conntrack_core.c:1606
 nf_hook_entry_hookfn include/linux/netfilter.h:119 [inline]
 nf_hook_slow+0xc5/0x1e0 net/netfilter/core.c:511
 nf_hook include/linux/netfilter.h:244 [inline]
 NF_HOOK include/linux/netfilter.h:287 [inline]
 ip6_xmit+0x1229/0x20a0 net/ipv6/ip6_output.c:313
 inet6_csk_xmit+0x2fb/0x5c0 net/ipv6/inet6_connection_sock.c:139
 __tcp_transmit_skb+0x1bb2/0x33f0 net/ipv4/tcp_output.c:1148
 tcp_transmit_skb net/ipv4/tcp_output.c:1164 [inline]
 tcp_write_wakeup+0x4f1/0x610 net/ipv4/tcp_output.c:3728
 tcp_send_probe0+0x46/0x400 net/ipv4/tcp_output.c:3750
 tcp_probe_timer net/ipv4/tcp_timer.c:385 [inline]
 tcp_write_timer_handler+0x8c2/0xa60 net/ipv4/tcp_timer.c:602
 tcp_write_timer+0x103/0x1b0 net/ipv4/tcp_timer.c:618
 call_timer_fn+0x177/0x700 kernel/time/timer.c:1338
 expire_timers+0x243/0x4e0 kernel/time/timer.c:1375
 __run_timers kernel/time/timer.c:1696 [inline]
 run_timer_softirq+0x21c/0x670 kernel/time/timer.c:1709
 __do_softirq+0x265/0x980 kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:372 [inline]
 irq_exit+0x215/0x260 kernel/softirq.c:412
 exiting_irq arch/x86/include/asm/apic.h:535 [inline]
 smp_apic_timer_interrupt+0x136/0x550 arch/x86/kernel/apic/apic.c:1098
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:894
 </IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:789 [inline]
RIP: 0010:qlink_free mm/kasan/quarantine.c:150 [inline]
RIP: 0010:qlist_free_all+0xfc/0x140 mm/kasan/quarantine.c:166
Code: 50 08 48 8d 4a ff 83 e2 01 48 0f 45 c1 4c 8b 70 18 e9 40 ff ff ff e8 e3 56 cf ff 48 83 3d 63 53 59 08 00 74 38 4c 89 ff 57 9d <0f> 1f 44 00 00 4d 85 e4 75 9e 49 c7 45 08 00 00 00 00 49 c7 45 00
RSP: 0018:ffff8880479d79f8 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000007 RBX: ffff888046842800 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff888043cdee48 RDI: 0000000000000286
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff888094551000
R13: ffff8880479d7a30 R14: ffff88813bff0940 R15: 0000000000000286
 quarantine_reduce+0x1a9/0x230 mm/kasan/quarantine.c:259
 kasan_kmalloc+0xa2/0x160 mm/kasan/kasan.c:538
 slab_post_alloc_hook mm/slab.h:445 [inline]
 slab_alloc mm/slab.c:3397 [inline]
 __do_kmalloc mm/slab.c:3725 [inline]
 __kmalloc+0x144/0x3c0 mm/slab.c:3736
 kmalloc include/linux/slab.h:520 [inline]
 sk_prot_alloc+0x1e2/0x2d0 net/core/sock.c:1466
 sk_alloc+0x36/0xec0 net/core/sock.c:1520
 __netlink_create+0x63/0x270 net/netlink/af_netlink.c:643
 netlink_create+0x3a1/0x5d0 net/netlink/af_netlink.c:706
 __sock_create+0x3d8/0x740 net/socket.c:1276
 sock_create net/socket.c:1316 [inline]
 __sys_socket+0xef/0x200 net/socket.c:1346
 __do_sys_socket net/socket.c:1355 [inline]
 __se_sys_socket net/socket.c:1353 [inline]
 __x64_sys_socket+0x6f/0xb0 net/socket.c:1353
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x466459
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff80caaf188 EFLAGS: 00000246 ORIG_RAX: 0000000000000029
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000466459
RDX: 0000000000000000 RSI: 0000000000000803 RDI: 0000000000000010
RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffc4cba2fdf R14: 00007ff80caaf300 R15: 0000000000022000
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 14965 Comm: syz-executor.4 Not tainted 4.19.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:ip_rcv_core+0x3db/0xc90 net/ipv4/ip_input.c:467
Code: 38 c2 7c 09 45 84 c0 0f 85 f7 05 00 00 66 83 79 06 00 ba 01 00 00 00 66 0f 45 51 06 4c 89 f9 48 c1 e9 03 0f b7 d2 65 48 01 16 <48> ba 00 00 00 00 00 fc ff df 0f b6 14 11 4c 89 f9 83 e1 07 38 ca
RSP: 0018:ffff8880ba007bf8 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffff888036f70940 RCX: 1ffff11003276392
RDX: 0000000000000001 RSI: 0000607f45c7b418 RDI: ffff8880193b1d46
RBP: ffff8880193b0e00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000000 R12: ffff8880193b0e84
R13: ffff8880193b0e80 R14: ffff8880193b0ec4 R15: ffff8880193b1c90
FS:  00007ff80ca8e700(0000) GS:ffff8880ba000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000201e3000 CR3: 00000000a0586000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 ip_rcv+0x9d/0x3c0 net/ipv4/ip_input.c:521
 __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:4954
 __netif_receive_skb+0x27/0x1c0 net/core/dev.c:5066
 process_backlog+0x241/0x700 net/core/dev.c:5848
 napi_poll net/core/dev.c:6272 [inline]
 net_rx_action+0x4ac/0xfb0 net/core/dev.c:6338
 __do_softirq+0x265/0x980 kernel/softirq.c:292
 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1092
 </IRQ>
 do_softirq.part.0+0x160/0x1c0 kernel/softirq.c:336
 do_softirq kernel/softirq.c:328 [inline]
 __local_bh_enable_ip+0x20e/0x270 kernel/softirq.c:189
 local_bh_enable include/linux/bottom_half.h:32 [inline]
 rcu_read_unlock_bh include/linux/rcupdate.h:721 [inline]
 ip_finish_output2+0xde2/0x15a0 net/ipv4/ip_output.c:232
 ip_do_fragment+0xe73/0x22c0 net/ipv4/ip_output.c:815
 ip_fragment.constprop.0+0x174/0x240 net/ipv4/ip_output.c:551
 ip_finish_output+0x7a4/0xd20 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:278 [inline]
 ip_output+0x203/0x5f0 net/ipv4/ip_output.c:406
 dst_output include/net/dst.h:455 [inline]
 ip_local_out+0xaf/0x170 net/ipv4/ip_output.c:125
 __ip_queue_xmit+0x866/0x1b50 net/ipv4/ip_output.c:506
 __tcp_transmit_skb+0x1bb2/0x33f0 net/ipv4/tcp_output.c:1148
 tcp_transmit_skb net/ipv4/tcp_output.c:1164 [inline]
 tcp_write_xmit+0x989/0x50f0 net/ipv4/tcp_output.c:2390
 __tcp_push_pending_frames+0xae/0x310 net/ipv4/tcp_output.c:2571
 tcp_push+0x4b7/0x6b0 net/ipv4/tcp.c:745
 tcp_sendmsg_locked+0x1553/0x2f60 net/ipv4/tcp.c:1419
 tcp_sendmsg+0x2b/0x40 net/ipv4/tcp.c:1462
 inet_sendmsg+0x132/0x5a0 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xc3/0x120 net/socket.c:632
 ___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2115
 __sys_sendmsg net/socket.c:2153 [inline]
 __do_sys_sendmsg net/socket.c:2162 [inline]
 __se_sys_sendmsg net/socket.c:2160 [inline]
 __x64_sys_sendmsg+0x132/0x220 net/socket.c:2160
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x466459
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff80ca8e188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000000000056c008 RCX: 0000000000466459
RDX: 0000000000000003 RSI: 0000000020000600 RDI: 0000000000000004
RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c008
R13: 00007ffc4cba2fdf R14: 00007ff80ca8e300 R15: 0000000000022000

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2021/04/01 14:52 linux-4.19.y 2034d6f0838e 6a81331a .config console log report info ci2-linux-4-19 BUG: soft lockup in tcp_write_timer
* Struck through repros no longer work on HEAD.