INFO: rcu detected stall in ip_expire (2)

Status: upstream: reported on 2026/10/05 00:10
Reported-by: syzbot+3857037c2b93f02661ef@syzkaller.appspotmail.com
First crash: 5d12h, last: 4d06h
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 INFO: rcu detected stall in ip_expire 1 2 4d05h 19d 0/2 upstream: reported on 2026/09/20 15:33
linux-6.1 INFO: rcu detected stall in ip_expire (2) 1 1 125d 125d 0/3 auto-obsoleted due to no activity on 2026/09/15 02:40
upstream INFO: rcu detected stall in ip_expire (2) net 1 1 2100d 2100d 0/29 auto-closed as invalid on 2021/04/09 11:48
linux-6.1 INFO: rcu detected stall in ip_expire 1 1 748d 748d 0/3 auto-obsoleted due to no activity on 2024/12/30 13:44
linux-5.15 INFO: rcu detected stall in ip_expire 1 1 316d 316d 0/3 auto-obsoleted due to no activity on 2026/03/08 05:26
upstream INFO: rcu detected stall in ip_expire net 1 1 2230d 2230d 0/29 auto-closed as invalid on 2020/11/30 05:39
upstream BUG: soft lockup in ip_expire net 1 1 383d 383d 0/29 closed as invalid on 2025/11/14 20:35

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (1 GPs behind) idle=6c3/1/0x4000000000000000 softirq=29955/29956 fqs=3537 
	(t=10500 jiffies g=43609 q=1867)
NMI backtrace for cpu 0
CPU: 0 PID: 12787 Comm: syz.0.3000 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 <IRQ>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 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+0x22d/0x380 kernel/rcu/tree_stall.h:349
 print_cpu_stall+0x31f/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+0x6ec/0x1120 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:2021
 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+0x4b0/0xb60 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x397/0x8b0 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:lock_acquire+0x209/0x400 kernel/locking/lockdep.c:5741
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3c 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 43 c7 44 3c 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc90000007a00 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: d728080b23dec600
RDX: 0000000000000000 RSI: ffffffff8a2b3e80 RDI: ffffffff8a7a4b80
RBP: ffffc90000007b18 R08: dffffc0000000000 R09: 1ffffffff2042818
R10: dffffc0000000000 R11: fffffbfff2042819 R12: 1ffff92000000f4c
R13: ffffffff8c31efa0 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 ip_expire+0x6b/0x6c0 net/ipv4/ip_fragment.c:145
 call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
 expire_timers kernel/time/timer.c:1699 [inline]
 __run_timers+0x56c/0x810 kernel/time/timer.c:1970
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
 handle_softirqs+0x336/0x830 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x13b/0x230 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:generic_exec_single+0x37d/0x470 kernel/smp.c:532
Code: df eb 27 e8 f5 82 0b 00 0f 0b e9 ac fd ff ff e8 e9 82 0b 00 e8 54 76 54 08 48 85 db 0f 84 5c ff ff ff e8 d6 82 0b 00 fb 31 c0 <48> c7 44 24 20 0e 36 e0 45 4b c7 44 3d 00 00 00 00 00 43 c7 44 3d
RSP: 0018:ffffc9000405fa60 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000200 RCX: 0000000000080000
RDX: ffffc9000d8a9000 RSI: 000000000000168d RDI: 000000000000168e
RBP: ffffc9000405fb30 R08: ffffffff902141cf R09: 1ffffffff2042839
R10: dffffc0000000000 R11: fffffbfff204283a R12: ffffc9000405fb88
R13: 1ffff9200080bf50 R14: 0000000000000000 R15: dffffc0000000000
 smp_call_function_single+0x202/0x4c0 kernel/smp.c:755
 task_function_call kernel/events/core.c:120 [inline]
 perf_install_in_context+0x5cf/0x930 kernel/events/core.c:3026
 __do_sys_perf_event_open kernel/events/core.c:12803 [inline]
 __se_sys_perf_event_open+0x12b3/0x1bb0 kernel/events/core.c:12397
 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: 0033:0x7f5288818199
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5286a4f028 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: ffffffffffffffda RBX: 00007f5288aa0090 RCX: 00007f5288818199
RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 00002000000012c0
RBP: 00007f52888af8e0 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5288aa0128 R14: 00007f5288aa0090 R15: 00007ffdec9e9088
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/06 06:32 linux-5.15.y a051a4bf909f f7710056 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in ip_expire
2026/10/05 00:10 linux-5.15.y a051a4bf909f 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in ip_expire
* Struck through repros no longer work on HEAD.