INFO: rcu detected stall in tcp_write_timer (3)

Status: auto-obsoleted due to no activity on 2026/01/22 20:12
Reported-by: syzbot+17b5e26c2a6a7eedcb8c@syzkaller.appspotmail.com
First crash: 339d, last: 324d
▶ ▼ Similar bugs (26)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in tcp_write_timer (2) bpf 1 2 2039d 2095d 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 780d 780d 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 1 4 689d 742d 0/3 auto-obsoleted due to no activity on 2025/01/22 08:13
upstream INFO: rcu detected stall in tcp_write_timer net 1 3 2588d 2583d 0/29 auto-closed as invalid on 2019/10/25 14:11
linux-5.15 INFO: rcu detected stall in tcp_write_timer (2) 1 2 475d 559d 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 1906d 1906d 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 575d 805d 0/3 auto-obsoleted due to no activity on 2025/05/16 12:07
upstream BUG: soft lockup in tcp_write_timer (4) mm 1 4 790d 814d 26/29 fixed on 2024/07/09 19:14
linux-6.1 INFO: rcu detected stall in tcp_write_timer (2) 1 3 62d 182d 0/3 upstream: reported on 2026/03/06 03:16
linux-5.15 INFO: rcu detected stall in tcp_write_timer (4) origin:lts-only 1 syz error 4 105d 186d 0/3 upstream: reported syz repro on 2026/03/01 05:59
linux-6.6 INFO: rcu detected stall in tcp_write_timer 1 7 8d11h 177d 0/2 upstream: reported on 2026/03/10 11:19
linux-4.14 INFO: rcu detected stall in tcp_write_timer 1 4 2190d 2433d 0/1 auto-closed as invalid on 2021/01/02 05:45
linux-4.19 INFO: rcu detected stall in tcp_write_timer 1 2 2319d 2373d 0/1 auto-closed as invalid on 2020/08/26 06:46
upstream BUG: soft lockup in tcp_write_timer (10) perf mm net 1 3 175d 205d 0/29 closed as invalid on 2026/03/27 01:43
linux-4.19 BUG: soft lockup in tcp_write_timer (3) 1 2 1343d 1356d 0/1 upstream: reported on 2022/12/17 21:41
linux-4.19 BUG: soft lockup in tcp_write_timer (2) 1 2 1752d 1816d 0/1 auto-closed as invalid on 2022/03/16 10:56
android-54 BUG: soft lockup in tcp_write_timer 1 1 488d 488d 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 1981d 1981d 0/1 auto-closed as invalid on 2021/07/30 14:52
upstream BUG: soft lockup in tcp_write_timer (9) net 1 2 269d 273d 0/29 closed as invalid on 2026/01/07 12:42
upstream BUG: soft lockup in tcp_write_timer (2) kvm 1 1 1592d 1592d 0/29 auto-closed as invalid on 2022/06/24 22:31
upstream BUG: soft lockup in tcp_write_timer (3) net 1 6 969d 1076d 0/29 closed as invalid on 2024/03/18 17:07
upstream BUG: soft lockup in tcp_write_timer (7) net 1 1 355d 355d 0/29 closed as invalid on 2025/09/29 07:16
upstream BUG: soft lockup in tcp_write_timer (8) mm 1 1 330d 330d 0/29 closed as invalid on 2025/11/04 11:28
upstream BUG: soft lockup in tcp_write_timer (6) bpf 1 1 402d 402d 0/29 closed as invalid on 2025/09/01 08:24
upstream BUG: soft lockup in tcp_write_timer (5) mm net 1 8 458d 520d 0/29 closed as invalid on 2025/07/11 15:27
android-5-15 BUG: soft lockup in tcp_write_timer 1 11 752d 865d 0/2 auto-obsoleted due to no activity on 2024/11/10 05:27

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (10498 ticks this GP) idle=4a3/1/0x4000000000000000 softirq=22367/22367 fqs=5237 
	(t=10502 jiffies g=29317 q=3137)
NMI backtrace for cpu 0
CPU: 0 PID: 8664 Comm: syz.7.920 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <IRQ>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_dump_cpu_stacks+0x22f/0x380 kernel/rcu/tree_stall.h:349
 print_cpu_stall+0x31d/0x5f0 kernel/rcu/tree_stall.h:633
 check_cpu_stall kernel/rcu/tree_stall.h:727 [inline]
 rcu_pending kernel/rcu/tree.c:3936 [inline]
 rcu_sched_clock_irq+0x6d8/0x1110 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:1818
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1108
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:check_kcov_mode kernel/kcov.c:172 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:227 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp8+0x1b/0x80 kernel/kcov.c:300
Code: 02 18 4a 89 44 02 20 48 ff c1 48 89 0a c3 90 48 8b 04 24 65 48 8b 0d 84 a1 8a 7e 65 8b 15 85 a1 8a 7e 81 e2 00 01 ff 00 74 11 <81> fa 00 01 00 00 75 57 83 b9 34 16 00 00 00 74 4e 8b 91 10 16 00
RSP: 0018:ffffc90000007ab8 EFLAGS: 00000206
RAX: ffffffff8167ffb9 RBX: 00000000012589c8 RCX: ffff888021140000
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 000000000000ecac R08: dffffc0000000000 R09: fffffbfff1ff7a32
R10: fffffbfff1ff7a32 R11: 1ffffffff1ff7a31 R12: 000000000000efa0
R13: 000000a583a6fb10 R14: ffffffffffffffff R15: 000001fb63109b96
 clocksource_delta kernel/time/timekeeping_internal.h:27 [inline]
 timekeeping_get_delta kernel/time/timekeeping.c:261 [inline]
 timekeeping_get_ns kernel/time/timekeeping.c:388 [inline]
 ktime_get+0x159/0x270 kernel/time/timekeeping.c:831
 ktime_get_ns include/linux/timekeeping.h:154 [inline]
 tcp_clock_ns include/net/tcp.h:775 [inline]
 tcp_mstamp_refresh+0x1c/0x90 net/ipv4/tcp_output.c:55
 tcp_write_timer_handler+0x1ad/0x9a0 net/ipv4/tcp_timer.c:643
 tcp_write_timer+0x126/0x280 net/ipv4/tcp_timer.c:675
 call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
 expire_timers kernel/time/timer.c:1496 [inline]
 __run_timers+0x525/0x7c0 kernel/time/timer.c:1767
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
 handle_softirqs+0x328/0x820 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:finish_lock_switch+0x134/0x280 kernel/sched/core.c:4804
Code: be ff ff ff ff e8 7c bd 55 08 85 c0 74 4a 4d 85 ff 75 66 0f 1f 44 00 00 48 89 df e8 36 28 5f 08 e8 a1 74 2a 00 fb 48 83 c4 08 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 48 89 df e8 d9 0f fe ff 43 80 3c
RSP: 0018:ffffc900036c7908 EFLAGS: 00000282
RAX: f8f5d1efbd870900 RBX: ffff8880b903a340 RCX: f8f5d1efbd870900
RDX: dffffc0000000000 RSI: ffffffff8a0b1820 RDI: ffffffff8a59a4c0
RBP: 1ffff11017207613 R08: dffffc0000000000 R09: fffffbfff1ff7a1f
R10: fffffbfff1ff7a1f R11: 1ffffffff1ff7a1e R12: 1ffff110172075c1
R13: dffffc0000000000 R14: ffff8880b903ae08 R15: 0000000000000000
 finish_task_switch+0x12f/0x640 kernel/sched/core.c:4921
 context_switch kernel/sched/core.c:5052 [inline]
 __schedule+0x11c3/0x4390 kernel/sched/core.c:6395
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6799
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:do_user_addr_fault+0x309/0xc80 arch/x86/mm/fault.c:-1
Code: 98 08 8a be 23 05 00 00 31 d2 e8 b2 22 1e 00 2e 2e 2e 31 c0 48 8b 7c 24 20 4c 89 fe e8 d0 5c 79 00 48 85 c0 0f 84 4f 05 00 00 <48> 89 c3 4c 89 64 24 08 49 89 c4 48 c1 e8 03 80 3c 28 00 74 08 4c
RSP: 0018:ffffc900036c7ce0 EFLAGS: 00000282
RAX: ffff88805e55cb58 RBX: 0000000000000001 RCX: ffff888021140000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: dffffc0000000000 R09: ffffed100fd63b78
R10: ffffed100fd63b78 R11: 1ffff1100fd63b77 R12: ffffc900036c7db8
R13: 0000000000000214 R14: 0000000000000000 R15: 0000000000000000
 handle_page_fault arch/x86/mm/fault.c:1445 [inline]
 exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1501
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606
RIP: 0010:do_strncpy_from_user lib/strncpy_from_user.c:72 [inline]
RIP: 0010:strncpy_from_user+0x271/0x360 lib/strncpy_from_user.c:139
Code: e9 93 00 00 00 e8 4f 95 7d fd 49 83 c5 08 4d 89 f4 4c 8b 74 24 08 4c 8b 3c 24 31 ff 4c 89 e6 e8 15 99 7d fd 49 83 ec 01 72 44 <43> 8a 2c 2f 4a 8d 3c 2b 48 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00
RSP: 0018:ffffc900036c7e60 EFLAGS: 00050212
RAX: ffffffff83fa351b RBX: ffff888058f73320 RCX: ffff888021140000
RDX: 0000000000000000 RSI: 0000000000000fe0 RDI: 0000000000000000
RBP: ffff888058f73320 R08: 0000000000000fe0 R09: 0000000000000020
R10: fffff940002c7b81 R11: 1ffffd40002c7b80 R12: 0000000000000fdf
R13: 0000000000000000 R14: 0000000000000fe0 R15: 0000000000000000
 getname_flags+0xef/0x500 fs/namei.c:149
 getname fs/namei.c:217 [inline]
 __do_sys_mkdirat fs/namei.c:4105 [inline]
 __se_sys_mkdirat fs/namei.c:4103 [inline]
 __x64_sys_mkdirat+0x78/0x90 fs/namei.c:4103
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f5bb003bec9
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5bae2a3038 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f5bb0292fa0 RCX: 00007f5bb003bec9
RDX: 00000000000001ff RSI: 0000000000000000 RDI: ffffffffffffff9c
RBP: 00007f5bb00bef91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5bb0293038 R14: 00007f5bb0292fa0 R15: 00007ffdda191e48
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/14 20:11 linux-5.15.y 29e53a5b1c4f b6605ba8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in tcp_write_timer
2025/09/29 07:40 linux-5.15.y 43bb85222e53 001c9061 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in tcp_write_timer
* Struck through repros no longer work on HEAD.