rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 1-...!: (2 ticks this GP) idle=078c/1/0x4000000000000000 softirq=18333/18333 fqs=0
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5724/1:b..l
rcu: (detected by 0, t=10503 jiffies, g=19153, q=434 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6416 Comm: syz.2.160 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:lookup_chain_cache kernel/locking/lockdep.c:3801 [inline]
RIP: 0010:lookup_chain_cache_add kernel/locking/lockdep.c:3821 [inline]
RIP: 0010:validate_chain kernel/locking/lockdep.c:3876 [inline]
RIP: 0010:__lock_acquire+0xb24/0x2cf0 kernel/locking/lockdep.c:5237
Code: b9 3a 90 48 bb eb 83 b5 80 46 86 c8 61 48 0f af dd 48 c1 eb 2d 48 8b 04 dd a0 e3 fc 93 48 85 c0 0f 94 c1 48 83 c0 f8 0f 94 c2 <08> ca 0f 84 1c 01 00 00 e8 ef d4 ff ff 85 c0 0f 84 d5 01 00 00 48
RSP: 0018:ffffc90000a08b80 EFLAGS: 00000097
RAX: ffffffff94416330 RBX: 0000000000033dff RCX: 0000000000040000
RDX: 0000000000d3da00 RSI: 000000004fa421e6 RDI: ffff888078c6bd80
RBP: 97064f26aa3bd169 R08: ffffffff84bc77fc R09: ffffffff9a681df0
R10: ffff888053fc6308 R11: ffffed100a7f8c63 R12: ffff888078c6c988
R13: ffff888078c6c988 R14: ffff888078c6bd80 R15: 0000000000000003
FS: 00007f848263a6c0(0000) GS:ffff88812538f000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0d811e8158 CR3: 00000000757f8000 CR4: 00000000003526f0
Call Trace:
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
_raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166
debug_object_deactivate+0x6c/0x3a0 lib/debugobjects.c:890
debug_hrtimer_deactivate kernel/time/hrtimer.c:490 [inline]
__run_hrtimer kernel/time/hrtimer.c:1898 [inline]
__hrtimer_run_queues+0x23a/0xa20 kernel/time/hrtimer.c:1994
hrtimer_interrupt+0x44b/0x950 kernel/time/hrtimer.c:2113
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
__sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1067
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1061
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80 kernel/locking/spinlock.c:198
Code: f7 e8 1d 25 f7 f5 f7 c3 00 02 00 00 74 05 e8 70 b8 22 f6 9c 58 a9 00 02 00 00 75 27 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 64 a7 e8 f5 65 8b 05 ed f0 8d 07 85 c0 74 18 5b 41 5e e9 51 48
RSP: 0018:ffffc9000cfaeee8 EFLAGS: 00000206
RAX: 0000000000000002 RBX: 0000000000000282 RCX: 0000000000000202
RDX: 0000000000000002 RSI: ffffffff8dfa89d3 RDI: 0000000000000001
RBP: ffffc9000cfaf1d0 R08: ffffffff9030a5f7 R09: 1ffffffff20614be
R10: dffffc0000000000 R11: fffffbfff20614bf R12: ffff888053fc6290
R13: dffffc0000000000 R14: ffff888053fc62a8 R15: ffff888053fc62f8
spin_unlock_irqrestore include/linux/spinlock.h:408 [inline]
taprio_change+0x30fe/0x3e50 net/sched/sch_taprio.c:1986
taprio_init+0x96f/0xbe0 net/sched/sch_taprio.c:2125
qdisc_create+0x7c4/0xf20 net/sched/sch_api.c:1319
__tc_modify_qdisc net/sched/sch_api.c:1753 [inline]
tc_modify_qdisc+0x16f0/0x2290 net/sched/sch_api.c:1817
rtnetlink_rcv_msg+0x77e/0xbe0 net/core/rtnetlink.c:7005
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
____sys_sendmsg+0x972/0x9f0 net/socket.c:2698
___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
__sys_sendmsg net/socket.c:2784 [inline]
__do_sys_sendmsg net/socket.c:2789 [inline]
__se_sys_sendmsg net/socket.c:2787 [inline]
__x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2787
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f848179cdd9
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:00007f848263a028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f8481a16090 RCX: 00007f848179cdd9
RDX: 0000000000000010 RSI: 00002000000012c0 RDI: 0000000000000006
RBP: 00007f8481832d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8481a16128 R14: 00007f8481a16090 R15: 00007ffce96e3128
task:udevd state:R running task stack:25624 pid:5724 tgid:5724 ppid:4992 task_flags:0x400140 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5387 [inline]
__schedule+0x17b4/0x5680 kernel/sched/core.c:7188
preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:7369
preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline]
_raw_spin_unlock_irqrestore+0x74/0x80 kernel/locking/spinlock.c:198
spin_unlock_irqrestore include/linux/spinlock.h:408 [inline]
__wake_up_common_lock+0x190/0x1f0 kernel/sched/wait.c:127
sock_def_readable+0x1eb/0x550 net/core/sock.c:3614
unix_dgram_sendmsg+0xdfd/0x18d0 net/unix/af_unix.c:2297
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
sock_write_iter+0x49b/0x4f0 net/socket.c:1254
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x61d/0xb90 fs/read_write.c:688
ksys_write+0x150/0x270 fs/read_write.c:740
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4d4aea7407
RSP: 002b:00007fffaf50de50 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f4d4b542880 RCX: 00007f4d4aea7407
RDX: 0000000000000000 RSI: 00007fffaf50def7 RDI: 000000000000000a
RBP: 000000000000000a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007f4d4b5426e8
R13: 0000000000000000 R14: 0000000000000000 R15: 000055dcdb4f2f10
rcu: rcu_preempt kthread starved for 10503 jiffies! g19153 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:27536 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5387 [inline]
__schedule+0x17b4/0x5680 kernel/sched/core.c:7188
__schedule_loop kernel/sched/core.c:7267 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7282
schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095
rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 5625 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0xfcf/0x13d0 kernel/smp.c:892
Code: 79 45 8b 2e 44 89 ee 83 e6 01 31 ff e8 7a 05 0c 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 25 01 0c 00 eb 37 f3 90 <43> 0f b6 04 2c 84 c0 75 10 41 f7 06 01 00 00 00 74 1e e8 0a 01 0c
RSP: 0018:ffffc90004357560 EFLAGS: 00000293
RAX: ffffffff81b9ab26 RBX: ffff8880b863c148 RCX: ffff888076ea3d80
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90004357688 R08: ffffffff9030a5f7 R09: 1ffffffff20614be
R10: dffffc0000000000 R11: fffffbfff20614bf R12: 1ffff110170e8169
R13: dffffc0000000000 R14: ffff8880b8740b48 R15: 0000000000000001
FS: 00005555674ad500(0000) GS:ffff88812528f000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffa3f5c1ff8 CR3: 00000000616ea000 CR4: 00000000003526f0
Call Trace:
on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1057
__flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline]
flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
flush_tlb_mm_range+0x5c3/0x10b0 arch/x86/mm/tlb.c:1451
dup_mmap+0x17a2/0x1d90 mm/mmap.c:1905
dup_mm kernel/fork.c:1534 [inline]
copy_mm+0x13b/0x4a0 kernel/fork.c:1586
copy_process+0x1f1c/0x4450 kernel/fork.c:2262
kernel_clone+0x284/0x8f0 kernel/fork.c:2723
__do_sys_clone kernel/fork.c:2864 [inline]
__se_sys_clone kernel/fork.c:2848 [inline]
__x64_sys_clone+0x1b6/0x230 kernel/fork.c:2848
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0d80fc5852
Code: 89 e7 e8 71 8b f7 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 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 66 89 c5 85 c0 75 3b 64 48 8b 04 25 10 00 00
RSP: 002b:00007fff28199cc0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007fff28199cc0 RCX: 00007f0d80fc5852
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007fff28199e4c R08: 0000000000000000 R09: 0000000000000001
R10: 00005555674ad7d0 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000000927c0 R14: 000000000001abff R15: 00007fff28199ea0