syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5159/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=9957, q=510 ncpus=2)
task:udevd           state:R  running task     stack:25032 pid:5159  ppid:1      flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6866
 preempt_schedule+0xab/0xc0 kernel/sched/core.c:6890
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0xfa/0x110 kernel/locking/spinlock.c:194
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 __wake_up_common_lock kernel/sched/wait.c:140 [inline]
 __wake_up_sync_key+0x11f/0x190 kernel/sched/wait.c:213
 sock_def_readable+0x1e1/0x430 net/core/sock.c:3329
 __netlink_sendskb net/netlink/af_netlink.c:1276 [inline]
 netlink_sendskb+0x9b/0x130 net/netlink/af_netlink.c:1282
 netlink_sendmsg+0x8c1/0xbe0 net/netlink/af_netlink.c:1904
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x5bf/0x950 net/socket.c:2595
 ___sys_sendmsg+0x220/0x290 net/socket.c:2649
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2687 [inline]
 __se_sys_sendmsg+0x1a5/0x270 net/socket.c:2685
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f5805ca7407
RSP: 002b:00007ffea6fb5fe0 EFLAGS: 00000202 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f5806367880 RCX: 00007f5805ca7407
RDX: 0000000000000000 RSI: 00007ffea6fb6040 RDI: 0000000000000004
RBP: 00005589511c04d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00000000000000b2
R13: 000055895109f9e0 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 10528 jiffies! g9957 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:26920 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_timeout+0x160/0x280 kernel/time/timer.c:2167
 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </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 PID: 6008 Comm: syz.1.18 Not tainted 6.6.102-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:__this_cpu_preempt_check+0x0/0x20 lib/smp_processor_id.c:65
Code: 48 89 da e8 f2 9c f4 ff 48 8b 74 24 30 48 c7 c7 40 67 fc 8a e8 e1 9c f4 ff e8 fc 7e ff ff eb a8 e8 c5 e8 ff ff 0f 1f 44 00 00 <f3> 0f 1e fa 48 89 fe 48 c7 c7 c0 66 fc 8a e9 dd fe ff ff cc cc cc
RSP: 0018:ffffc90000007c38 EFLAGS: 00000092
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff81671700
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8aaacb40
RBP: ffffc90000007d48 R08: dffffc0000000000 R09: 1ffffffff21b46a1
R10: dffffc0000000000 R11: fffffbfff21b46a2 R12: 1ffff92000000f94
R13: ffffffff8cd49c48 R14: 0000000000000046 R15: dffffc0000000000
FS:  00005555745d5500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000006b000 CR3: 0000000031ee2000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 lockdep_recursion_finish kernel/locking/lockdep.c:467 [inline]
 lock_acquire+0x1a7/0x410 kernel/locking/lockdep.c:5756
 seqcount_lockdep_reader_access+0xca/0x1c0 include/linux/seqlock.h:102
 ktime_get+0x35/0x280 kernel/time/timekeeping.c:846
 clockevents_program_event+0xe6/0x310 kernel/time/clockevents.c:326
 hrtimer_interrupt+0x5a1/0x9c0 kernel/time/hrtimer.c:1894
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline]
 __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:202
Code: 00 f3 0f 1e fa 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 aa 8f f0 f6 48 89 df e8 c2 61 f1 f6 e8 7d fd 14 f7 fb bf 01 00 00 00 <e8> 12 7a e4 f6 65 8b 05 33 c9 8c 75 85 c0 74 02 5b c3 e8 10 ab 89
RSP: 0018:ffffc90003697c98 EFLAGS: 00000282
RAX: 9358cb2c00b72800 RBX: ffff88802fa25c80 RCX: 9358cb2c00b72800
RDX: dffffc0000000000 RSI: ffffffff8aaab9c0 RDI: 0000000000000001
RBP: ffff88802fa26118 R08: ffffffff8e4a882f R09: 1ffffffff1c95105
R10: dffffc0000000000 R11: fffffbfff1c95106 R12: 1ffff11005f44c23
R13: 0000000000000021 R14: dffffc0000000000 R15: 0000000000000000
 spin_unlock_irq include/linux/spinlock.h:401 [inline]
 get_signal+0x11f5/0x1400 kernel/signal.c:2905
 arch_do_signal_or_restart+0x96/0x780 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f2d0b38ebe9
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:00007ffc98827338 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 00007f2d0b5b5fa0 RCX: 00007f2d0b38ebe9
RDX: 000020000006b000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f2d0b411e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2d0b5b5fa0 R14: 00007f2d0b5b5fa0 R15: 0000000000000004
 </TASK>
sched: RT throttling activated