INFO: rcu detected stall in netlink_sendmsg (5)

Status: closed as invalid on 2026/04/30 15:35
Subsystems: net
[Documentation on labels]
First crash: 254d, last: 154d
Cause bisection: failed (error log, bisect log)
  
▶ ▼ Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in netlink_sendmsg (2) 1 syz, C done 11 2521d 2527d 13/29 fixed on 2019/10/09 10:54
upstream INFO: rcu detected stall in netlink_sendmsg (6) prio:low mm kernfs 1 syz, C error 25 5h16m 8d19h 0/29 upstream: reported C repro on 2026/08/02 00:00
linux-4.19 INFO: rcu detected stall in netlink_sendmsg 1 syz, C done 3 2519d 2524d 1/1 fixed on 2019/12/10 03:52
upstream INFO: rcu detected stall in netlink_sendmsg (3) net 1 syz, C done 6 2372d 2425d 15/29 fixed on 2020/02/18 14:31
upstream INFO: rcu detected stall in netlink_sendmsg netfilter 1 syz 83 2730d 2786d 11/29 fixed on 2019/03/06 07:43
upstream INFO: rcu detected stall in netlink_sendmsg (4) net 1 syz, C done error 38 1132d 2323d 0/29 auto-obsoleted due to no activity on 2025/10/27 20:35
linux-4.14 BUG: soft lockup in netlink_sendmsg 1 1 1672d 1672d 0/1 auto-closed as invalid on 2022/05/11 11:30
linux-4.19 BUG: soft lockup in netlink_sendmsg 1 syz, C error 8 1306d 1956d 0/1 upstream: reported C repro on 2021/04/02 18:46
▶ ▼ Last patch testing requests (10)
Created Duration User Patch Repo Result
2026/04/02 05:51 26m retest repro linux-next OK log
2026/04/02 05:07 33m retest repro linux-next report log
2026/04/02 05:07 22m retest repro linux-next OK log
2026/04/02 04:00 27m retest repro linux-next OK log
2026/04/02 04:00 35m retest repro linux-next report log
2026/04/02 04:00 22m retest repro linux-next report log
2026/01/22 04:26 17m retest repro linux-next error
2026/01/22 03:13 34m retest repro linux-next error
2026/01/22 03:13 22m retest repro linux-next report log
2026/01/22 03:13 14m retest repro linux-next error

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5944/1:b..l
rcu: 	(detected by 1, t=10503 jiffies, g=14381, q=193 ncpus=2)
task:syz-executor    state:R  running task     stack:19496 pid:5944  tgid:5944  ppid:5939   task_flags:0x400140 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5282 [inline]
 __schedule+0x14ed/0x5040 kernel/sched/core.c:6894
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7221
 irqentry_exit+0x5e3/0x670 kernel/entry/common.c:216
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:check_kcov_mode kernel/kcov.c:194 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:246 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x37/0x90 kernel/kcov.c:314
Code: 08 00 c6 92 65 8b 0d 08 00 05 11 81 e1 00 01 ff 00 74 11 81 f9 00 01 00 00 75 5b 83 ba 44 16 00 00 00 74 52 8b 8a 20 16 00 00 <83> f9 03 75 47 48 8b 8a 28 16 00 00 44 8b 8a 24 16 00 00 49 c1 e1
RSP: 0018:ffffc90003fae768 EFLAGS: 00000246
RAX: ffffffff81d027fe RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88802faddac0 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffffffff81d02626 R09: ffffffff8e33efa0
R10: ffffc90003fae858 R11: ffffffff81acf3b0 R12: 0000000000000004
R13: dffffc0000000000 R14: 00007f81293915dc R15: 0000000000000000
 rcu_read_unlock include/linux/rcupdate.h:879 [inline]
 is_bpf_text_address+0x1fe/0x2b0 kernel/bpf/core.c:750
 kernel_text_address+0xa5/0xe0 kernel/extable.c:125
 __kernel_text_address+0xd/0x40 kernel/extable.c:79
 unwind_get_return_address+0x4d/0x90 arch/x86/kernel/unwind_orc.c:385
 arch_stack_walk+0xfc/0x150 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5267 [inline]
 kmem_cache_alloc_lru_noprof+0x36c/0x6e0 mm/slub.c:5286
 __d_alloc+0x37/0x6f0 fs/dcache.c:1730
 d_alloc+0x4b/0x190 fs/dcache.c:1809
 lookup_one_qstr_excl+0xdc/0x360 fs/namei.c:1743
 __start_dirop fs/namei.c:2866 [inline]
 start_dirop+0x5c/0x90 fs/namei.c:2875
 simple_start_creating+0xc4/0x100 fs/libfs.c:2330
 debugfs_start_creating+0xdb/0x1a0 fs/debugfs/inode.c:394
 __debugfs_create_file+0x6f/0x400 fs/debugfs/inode.c:428
 debugfs_create_file_short+0x3f/0x60 fs/debugfs/inode.c:471
 add_sta_files net/mac80211/debugfs_netdev.c:843 [inline]
 add_files net/mac80211/debugfs_netdev.c:957 [inline]
 ieee80211_debugfs_add_netdev net/mac80211/debugfs_netdev.c:1010 [inline]
 ieee80211_debugfs_recreate_netdev+0xba3/0x1450 net/mac80211/debugfs_netdev.c:1034
 ieee80211_if_add+0xc3d/0x13a0 net/mac80211/iface.c:2311
 ieee80211_register_hw+0x35d9/0x4110 net/mac80211/main.c:1607
 mac80211_hwsim_new_radio+0x2f6d/0x52f0 drivers/net/wireless/virtual/mac80211_hwsim.c:5810
 hwsim_new_radio_nl+0xf5b/0x1bd0 drivers/net/wireless/virtual/mac80211_hwsim.c:6504
 genl_family_rcv_msg_doit+0x215/0x300 net/netlink/genetlink.c:1115
 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
 genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2550
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec+0x18f/0x1d0 net/socket.c:737
 __sock_sendmsg net/socket.c:752 [inline]
 __sys_sendto+0x3ce/0x540 net/socket.c:2221
 __do_sys_sendto net/socket.c:2228 [inline]
 __se_sys_sendto net/socket.c:2224 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2224
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f81293915dc
RSP: 002b:00007ffe05824fd0 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f812a114620 RCX: 00007f81293915dc
RDX: 0000000000000024 RSI: 00007f812a114670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffe05825024 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f812a114670 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 10486 jiffies! g14381 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:27976 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5282 [inline]
 __schedule+0x14ed/0x5040 kernel/sched/core.c:6894
 __schedule_loop kernel/sched/core.c:6976 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6991
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x11b0 kernel/rcu/tree.c:2095
 rcu_gp_kthread+0x9b/0x2d0 kernel/rcu/tree.c:2297
 kthread+0x389/0x480 kernel/kthread.c:467
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6034 Comm: syz.2.19 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__kasan_check_byte+0x4/0x40 mm/kasan/common.c:572
Code: 4c 89 f6 5b 41 5c 41 5e 41 5f e9 c7 fa ff ff 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 <41> 56 53 48 89 f3 49 89 fe e8 3e 15 00 00 84 c0 75 16 be 01 00 00
RSP: 0018:ffffc90002e77bd8 EFLAGS: 00000002
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000080000002
RDX: 0000000000000000 RSI: ffffffff8b69171d RDI: ffff88801cfdae58
RBP: ffffffff8187d5e9 R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f87cef R12: 0000000000000000
R13: ffff88801cfdae58 R14: 0000000000000000 R15: 0000000000000001
FS:  000055556a488500(0000) GS:ffff8881259c0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2ea63fff CR3: 000000005edb8000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 kasan_check_byte include/linux/kasan.h:402 [inline]
 lock_acquire+0x84/0x340 kernel/locking/lockdep.c:5842
 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:142 [inline]
 _raw_spin_lock_irq+0x3d/0x50 kernel/locking/spinlock.c:170
 spin_lock_irq include/linux/spinlock.h:374 [inline]
 get_signal+0x239/0x1340 kernel/signal.c:2823
 arch_do_signal_or_restart+0x9a/0x7a0 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
 exit_to_user_mode_loop+0x87/0x4e0 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x2c1/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7efee098f749
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:00007ffda2844ba8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 00007efee0be5fa0 RCX: 00007efee098f749
RDX: 0000200000000300 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007efee0a13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007efee0be5fa0 R14: 00007efee0be5fa0 R15: 0000000000000004
 </TASK>

Crashes (11):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/08 02:49 linux-next f96074c6d01d d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: rcu detected stall in netlink_sendmsg
2026/01/03 13:31 linux-next cc3aa43b44bd d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: rcu detected stall in netlink_sendmsg
2025/12/03 01:17 linux-next 7d31f578f323 d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: rcu detected stall in netlink_sendmsg
2025/12/11 23:56 upstream d358e5254674 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in netlink_sendmsg
2026/03/08 23:32 linux-next a0ae2a256046 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: rcu detected stall in netlink_sendmsg
2026/01/07 11:58 linux-next f96074c6d01d d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: rcu detected stall in netlink_sendmsg
2026/01/04 05:14 linux-next cc3aa43b44bd d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: rcu detected stall in netlink_sendmsg
2025/12/29 07:49 linux-next cc3aa43b44bd d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: rcu detected stall in netlink_sendmsg
2025/12/25 23:02 linux-next cc3aa43b44bd d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: rcu detected stall in netlink_sendmsg
2025/12/20 11:53 linux-next cc3aa43b44bd d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: rcu detected stall in netlink_sendmsg
2025/11/28 21:09 linux-next 7d31f578f323 d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: rcu detected stall in netlink_sendmsg
* Struck through repros no longer work on HEAD.