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INFO: rcu detected stall in rtnl_dellink (2)

Status: upstream: reported on 2026/02/05 02:24
Reported-by: syzbot+8f938bb07bba5be3eaeb@syzkaller.appspotmail.com
First crash: 4d04h, last: 4d04h
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in rtnl_dellink 1 1 351d 351d 0/3 auto-obsoleted due to no activity on 2025/06/03 01:04
linux-6.6 INFO: rcu detected stall in rtnl_dellink 1 1 15d 15d 0/2 upstream: reported on 2026/01/25 01:43
upstream INFO: rcu detected stall in rtnl_dellink net 1 2 351d 419d 0/29 auto-obsoleted due to no activity on 2025/05/23 22:00
linux-5.15 INFO: rcu detected stall in rtnl_dellink 1 3 138d 218d 0/3 auto-obsoleted due to no activity on 2026/01/01 07:23

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-.... } 2631 jiffies s: 241089 root: 0x2/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 32608 Comm: syz.4.7724 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__lock_acquire+0x1354/0x7d10 kernel/locking/lockdep.c:5046
Code: fc ff df 42 0f b6 04 00 84 c0 0f 85 b4 5b 00 00 83 3d 8f 48 5b 15 00 0f 84 11 05 00 00 31 db 48 83 c3 40 48 89 d8 48 c1 e8 03 <42> 80 3c 00 00 74 12 48 89 df e8 8d 04 6f 00 49 b8 00 00 00 00 00
RSP: 0018:ffffc900001e0200 EFLAGS: 00000802
RAX: 1ffffffff208f820 RBX: ffffffff9047c100 RCX: ffffffff81645864
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90af3240
RBP: ffffc900001e0450 R08: dffffc0000000000 R09: 1ffffffff215e648
R10: dffffc0000000000 R11: fffffbfff215e649 R12: 00000000a00424dd
R13: 000000007d6f40c2 R14: 00000000334dffec R15: ffff88802c91c650
FS:  00007f4cc08916c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001b00 CR3: 0000000035c04000 CR4: 00000000003506e0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock_sched include/linux/rcupdate.h:883 [inline]
 pfn_valid include/linux/mmzone.h:1857 [inline]
 __virt_addr_valid+0x1a5/0x540 arch/x86/mm/physaddr.c:65
 kasan_addr_to_slab+0x9/0xc0 mm/kasan/common.c:36
 __kasan_record_aux_stack+0xf/0xc0 mm/kasan/generic.c:471
 irq_work_queue_on+0x10f/0x260 kernel/irq_work.c:140
 rcu_read_unlock_special+0x3c9/0x510 kernel/rcu/tree_plugin.h:678
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:823 [inline]
 trace_call_bpf+0x5bb/0x6b0 kernel/trace/bpf_trace.c:137
 perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:9997
 perf_trace_preemptirq_template+0x268/0x320 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0xd3/0x140 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x24/0x40 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:rcu_read_unlock_special+0x7f/0x510 kernel/rcu/tree_plugin.h:685
Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 92 30 95 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc900001e0aa0 EFLAGS: 00000206
RAX: 50a946bd44f41600 RBX: 1ffff9200003c15c RCX: 50a946bd44f41600
RDX: dffffc0000000000 RSI: ffffffff8a8c1220 RDI: ffffffff8adf0c20
RBP: ffffc900001e0b90 R08: ffffffff90af324f R09: 1ffffffff215e649
R10: dffffc0000000000 R11: fffffbfff215e64a R12: 0000000000000246
R13: dffffc0000000000 R14: ffff8880b8f3b900 R15: 0000000000000002
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:823 [inline]
 ieee80211_iterate_active_interfaces_atomic+0x156/0x170 net/mac80211/util.c:826
 mac80211_hwsim_beacon+0xb7/0x1b0 drivers/net/wireless/mac80211_hwsim.c:2147
 __run_hrtimer kernel/time/hrtimer.c:1747 [inline]
 __hrtimer_run_queues+0x560/0xd70 kernel/time/hrtimer.c:1811
 hrtimer_run_softirq+0x183/0x2a0 kernel/time/hrtimer.c:1828
 handle_softirqs+0x2a1/0x930 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:drop_sysctl_table+0x0/0x4e0 fs/proc/proc_sysctl.c:1719
Code: ff 48 8b 14 24 e9 0f f8 ff ff 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c b1 f9 ff ff 48 89 df e8 08 b9 cd ff e9 a4 f9 ff ff 0f 1f 00 <55> 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 e4 e0 48 81 ec 00 01
RSP: 0018:ffffc90004c0edb8 EFLAGS: 00000246
RAX: 50a946bd44f41600 RBX: ffff88802c680c00 RCX: 0000000000000001
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff88802c680c00
RBP: 0000000000000001 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000981da8 R12: ffff888055d7a800
R13: dffffc0000000000 R14: ffff88802c680c20 R15: ffff88802c680c00
 unregister_sysctl_table+0x85/0x130 fs/proc/proc_sysctl.c:1769
 mpls_dev_sysctl_unregister+0x8b/0xc0 net/mpls/af_mpls.c:1445
 mpls_dev_notify+0x555/0x760 net/mpls/af_mpls.c:1657
 notifier_call_chain kernel/notifier.c:87 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:455
 call_netdevice_notifiers_extack net/core/dev.c:2039 [inline]
 call_netdevice_notifiers net/core/dev.c:2053 [inline]
 unregister_netdevice_many+0x1086/0x1930 net/core/dev.c:10990
 rtnl_delete_link net/core/rtnetlink.c:3175 [inline]
 rtnl_dellink+0x538/0x7d0 net/core/rtnetlink.c:3226
 rtnetlink_rcv_msg+0x87c/0xfc0 net/core/rtnetlink.c:6150
 netlink_rcv_skb+0x1fb/0x450 net/netlink/af_netlink.c:2511
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x74d/0x8d0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1872
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x5be/0x970 net/socket.c:2518
 ___sys_sendmsg+0x2a2/0x360 net/socket.c:2572
 __sys_sendmsg net/socket.c:2601 [inline]
 __do_sys_sendmsg net/socket.c:2610 [inline]
 __se_sys_sendmsg+0x1bb/0x2a0 net/socket.c:2608
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f4cbf99aeb9
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:00007f4cc0891028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f4cbfc15fa0 RCX: 00007f4cbf99aeb9
RDX: 0000000000000000 RSI: 00002000000002c0 RDI: 0000000000000005
RBP: 00007f4cbfa08c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4cbfc16038 R14: 00007f4cbfc15fa0 R15: 00007fff2ba0f788
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/05 02:23 linux-6.1.y cd9b81672742 ea10c935 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in rtnl_dellink
* Struck through repros no longer work on HEAD.