syzbot


INFO: rcu detected stall in rtnl_getlink

Status: closed as invalid on 2025/09/01 08:24
Subsystems: net
[Documentation on labels]
First crash: 75d, last: 75d
Cause bisection: failed (error log, bisect log)
  
Last patch testing requests (1)
Created Duration User Patch Repo Result
2025/08/13 04:52 1h27m retest repro net report log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=ee04/1/0x4000000000000000 softirq=19218/19218 fqs=0
rcu: 	(detected by 0, t=10504 jiffies, g=13901, q=3134 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 5980 Comm: syz-executor Not tainted 6.16.0-rc7-syzkaller-00100-gafd8c2c9e2e2 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:lock_is_held_type+0x0/0x190 kernel/locking/lockdep.c:5928
Code: 6a 16 f6 90 0f 0b 90 90 90 eb b5 e8 1a fc ff ff 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 55 41 57 41 56 41 55 41 54 53 48 83 ec 10 65 48 8b 05
RSP: 0018:ffffc90000a08c68 EFLAGS: 00000002
RAX: ffffffff898d67c4 RBX: 0000000000000001 RCX: 0000000000010000
RDX: ffff888025829e00 RSI: 00000000ffffffff RDI: ffff8880246ab300
RBP: 0000000000000002 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200014117c R12: ffff8880246ab340
R13: ffff8880246ab000 R14: dffffc0000000000 R15: ffff88802582a8d8
FS:  0000555566f07500(0000) GS:ffff888125d23000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555569eb25c8 CR3: 0000000074f14000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 lock_is_held include/linux/lockdep.h:249 [inline]
 advance_sched+0xe7/0xc90 net/sched/sch_taprio.c:925
 __run_hrtimer kernel/time/hrtimer.c:1761 [inline]
 __hrtimer_run_queues+0x52c/0xc60 kernel/time/hrtimer.c:1825
 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline]
 __sysvec_apic_timer_interrupt+0x108/0x410 arch/x86/kernel/apic/apic.c:1056
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1050
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_release+0x2b5/0x3e0 kernel/locking/lockdep.c:5896
Code: 51 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 75 56 f7 c3 00 02 00 00 74 01 fb 65 48 8b 05 fb 81 01 11 <48> 3b 44 24 28 0f 85 8b 00 00 00 48 83 c4 30 5b 41 5c 41 5d 41 5e
RSP: 0018:ffffc90003236da8 EFLAGS: 00000206
RAX: 0e1d170815068e00 RBX: 0000000000000283 RCX: 0e1d170815068e00
RDX: 0000000000000001 RSI: ffffffff8db8463f RDI: ffffffff8be28d40
RBP: ffff88802582a918 R08: 0000000000000000 R09: ffffffff8214ee0d
R10: ffffc90003236f48 R11: fffff52000646dfe R12: 0000000000000001
R13: 0000000000000001 R14: ffffffff8e2456e0 R15: ffff888025829e00
 might_alloc include/linux/sched/mm.h:319 [inline]
 slab_pre_alloc_hook mm/slub.c:4099 [inline]
 slab_alloc_node mm/slub.c:4177 [inline]
 __do_kmalloc_node mm/slub.c:4327 [inline]
 __kmalloc_noprof+0xa3/0x4f0 mm/slub.c:4340
 kmalloc_noprof include/linux/slab.h:909 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 fib6_info_alloc+0x30/0xf0 net/ipv6/ip6_fib.c:155
 ip6_route_info_create+0x142/0x860 net/ipv6/route.c:3811
 ip6_route_add+0x49/0x1b0 net/ipv6/route.c:3940
 addrconf_add_mroute net/ipv6/addrconf.c:2551 [inline]
 addrconf_add_dev+0x24f/0x340 net/ipv6/addrconf.c:2569
 addrconf_dev_config net/ipv6/addrconf.c:3477 [inline]
 addrconf_init_auto_addrs+0x5c4/0xab0 net/ipv6/addrconf.c:3566
 addrconf_notify+0xacc/0x1010 net/ipv6/addrconf.c:3739
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 netif_state_change+0x284/0x3a0 net/core/dev.c:1584
 linkwatch_do_dev+0x117/0x170 net/core/link_watch.c:186
 linkwatch_sync_dev+0x27f/0x390 net/core/link_watch.c:289
 rtnl_getlink+0x64f/0xb50 net/core/rtnetlink.c:4171
 rtnetlink_rcv_msg+0x779/0xb70 net/core/rtnetlink.c:6953
 netlink_rcv_skb+0x205/0x470 net/netlink/af_netlink.c:2552
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x759/0x8e0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:727
 __sys_sendto+0x3bd/0x520 net/socket.c:2180
 __do_sys_sendto net/socket.c:2187 [inline]
 __se_sys_sendto net/socket.c:2183 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2183
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3cf459083c
Code: 2a 5f 02 00 44 8b 4c 24 2c 4c 8b 44 24 20 89 c5 44 8b 54 24 28 48 8b 54 24 18 b8 2c 00 00 00 48 8b 74 24 10 8b 7c 24 08 0f 05 <48> 3d 00 f0 ff ff 77 34 89 ef 48 89 44 24 08 e8 70 5f 02 00 48 8b
RSP: 002b:00007ffdf5c965d0 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f3cf52e4620 RCX: 00007f3cf459083c
RDX: 0000000000000020 RSI: 00007f3cf52e4670 RDI: 0000000000000005
RBP: 0000000000000000 R08: 00007ffdf5c96624 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000005
R13: 00007ffdf5c9668c R14: 00007f3cf52e4670 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 10504 jiffies! g13901 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:26632 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5397 [inline]
 __schedule+0x16fd/0x4cf0 kernel/sched/core.c:6786
 __schedule_loop kernel/sched/core.c:6864 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6879
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2054
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2256
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 5976 Comm: syz-executor Not tainted 6.16.0-rc7-syzkaller-00100-gafd8c2c9e2e2 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:csd_lock_wait kernel/smp.c:340 [inline]
RIP: 0010:smp_call_function_many_cond+0xf72/0x12d0 kernel/smp.c:885
Code: 01 31 ff e8 90 6e 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 3b 6a 0b 00 eb 37 f3 90 43 0f b6 04 2c 84 c0 75 10 <41> f7 07 01 00 00 00 74 1e e8 20 6a 0b 00 eb e5 44 89 f9 80 e1 07
RSP: 0018:ffffc90003437560 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff8880b863b1c0 RCX: ffff88805104da00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900034376c0 R08: ffffffff8fa1def7 R09: 1ffffffff1f43bde
R10: dffffc0000000000 R11: fffffbfff1f43bdf R12: 1ffff110170e7f5d
R13: dffffc0000000000 R14: 0000000000000001 R15: ffff8880b873fae8
FS:  0000555569e97500(0000) GS:ffff888125c23000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8bd48e56c0 CR3: 0000000052542000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1052
 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline]
 flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
 flush_tlb_mm_range+0x6b1/0x12c0 arch/x86/mm/tlb.c:1451
 dup_mmap+0x15a0/0x1ac0 mm/mmap.c:1877
 dup_mm kernel/fork.c:1477 [inline]
 copy_mm+0x13c/0x4b0 kernel/fork.c:1529
 copy_process+0x16d3/0x3b80 kernel/fork.c:2169
 kernel_clone+0x21e/0x870 kernel/fork.c:2599
 __do_sys_clone kernel/fork.c:2742 [inline]
 __se_sys_clone kernel/fork.c:2726 [inline]
 __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2726
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8bd3b85213
Code: 1f 84 00 00 00 00 00 64 48 8b 04 25 10 00 00 00 45 31 c0 31 d2 31 f6 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 89 c2 85 c0 75 2c 64 48 8b 04 25 10 00 00
RSP: 002b:00007ffcd4a52d58 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f8bd3b85213
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001
R10: 0000555569e977d0 R11: 0000000000000246 R12: 0000000000000000
R13: 00000000000927c0 R14: 00000000000263f8 R15: 00007ffcd4a52ef0
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/28 18:30 net afd8c2c9e2e2 c4a95487 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: rcu detected stall in rtnl_getlink
* Struck through repros no longer work on HEAD.