rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5136/1:b..l
rcu: (detected by 0, t=10503 jiffies, g=10965, q=814 ncpus=2)
task:udevd state:R running task stack:25160 pid:5136 ppid:1 flags:0x00004002
Call Trace:
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x1553/0x45a0 kernel/sched/core.c:6700
preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6867
preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6891
preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
__raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
_raw_spin_unlock+0x3a/0x40 kernel/locking/spinlock.c:186
spin_unlock include/linux/spinlock.h:391 [inline]
__d_lookup+0x64a/0x7c0 fs/dcache.c:2507
lookup_fast+0x7c/0x4d0 fs/namei.c:1660
walk_component fs/namei.c:2006 [inline]
link_path_walk+0x5ff/0xe30 fs/namei.c:2337
path_lookupat+0x9d/0x440 fs/namei.c:2490
filename_lookup+0x228/0x560 fs/namei.c:2520
user_path_at_empty+0x42/0x60 fs/namei.c:2917
do_readlinkat+0xdd/0x490 fs/stat.c:494
__do_sys_readlink fs/stat.c:527 [inline]
__se_sys_readlink fs/stat.c:524 [inline]
__x64_sys_readlink+0x7f/0x90 fs/stat.c:524
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f04b7f153a7
RSP: 002b:00007fff796da508 EFLAGS: 00000246 ORIG_RAX: 0000000000000059
RAX: ffffffffffffffda RBX: 00007fff796da9e0 RCX: 00007f04b7f153a7
RDX: 0000000000000400 RSI: 00007fff796da510 RDI: 00007fff796da9e0
RBP: 00007fff796da510 R08: 0000000000000075 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000400
R13: 00005585b74bb100 R14: 0000000000000007 R15: 00007fff796dc2e0
rcu: rcu_preempt kthread starved for 10531 jiffies! g10965 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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:27720 pid:17 ppid:2 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x1553/0x45a0 kernel/sched/core.c:6700
schedule+0xbd/0x170 kernel/sched/core.c:6774
schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
rcu_gp_fqs_loop+0x313/0x1590 kernel/rcu/tree.c:1667
rcu_gp_kthread+0x9d/0x3b0 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
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5907 Comm: syz.1.15 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:lockdep_recursion_finish kernel/locking/lockdep.c:467 [inline]
RIP: 0010:lock_release+0x54e/0x8c0 kernel/locking/lockdep.c:5776
Code: 24 18 48 8b 54 24 48 e8 a0 72 00 00 4c 8b 7c 24 08 48 c7 c7 80 da ca 8a e8 9f a8 1b 09 b8 ff ff ff ff 65 0f c1 05 8a e0 99 7e <83> f8 01 75 7f 43 c6 44 2f 04 00 48 c7 84 24 80 00 00 00 00 00 00
RSP: 0018:ffffc900001f0b00 EFLAGS: 00000057
RAX: 0000000000000001 RBX: b9733d4494fb5f65 RCX: 48bb51fade4a1600
RDX: 00000000ffffffff RSI: ffffffff8acada80 RDI: ffffffff8b1c81e0
RBP: ffffc900001f0c20 R08: dffffc0000000000 R09: 1ffffffff2237ea2
R10: dffffc0000000000 R11: fffffbfff2237ea3 R12: ffff888079eca930
R13: dffffc0000000000 R14: ffff888079eca8d0 R15: 1ffff9200003e16c
FS: 00007fc8167b16c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2ad78b CR3: 0000000075ea7000 CR4: 00000000003506e0
Call Trace:
rcu_lock_release include/linux/rcupdate.h:344 [inline]
rcu_read_unlock include/linux/rcupdate.h:819 [inline]
__lock_task_sighand+0x2b4/0x2d0 kernel/signal.c:1429
lock_task_sighand include/linux/sched/signal.h:742 [inline]
send_sigqueue+0x239/0x710 kernel/signal.c:2009
posix_timer_event kernel/time/posix-timers.c:299 [inline]
posix_timer_fn+0x16e/0x3d0 kernel/time/posix-timers.c:325
__run_hrtimer kernel/time/hrtimer.c:1750 [inline]
__hrtimer_run_queues+0x52a/0xc40 kernel/time/hrtimer.c:1814
hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1876
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
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 7a be da f6 48 89 df e8 32 93 db f6 e8 bd 9e ff f6 fb bf 01 00 00 00 42 99 ce f6 65 8b 05 13 d0 75 75 85 c0 74 02 5b c3 e8 90 b7 72
RSP: 0018:ffffc90004b7fd20 EFLAGS: 00000282
RAX: 48bb51fade4a1600 RBX: ffff88805bd065c0 RCX: 48bb51fade4a1600
RDX: dffffc0000000000 RSI: ffffffff8acac900 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffffffff8e8adfaf R09: 1ffffffff1d15bf5
R10: dffffc0000000000 R11: fffffbfff1d15bf6 R12: 0000000000000000
R13: 0000000100000000 R14: ffff888079ec9e00 R15: 0000000000000020
set_current_blocked kernel/signal.c:3077 [inline]
signal_delivered kernel/signal.c:2938 [inline]
signal_setup_done+0x189/0x310 kernel/signal.c:2950
handle_signal arch/x86/kernel/signal.c:285 [inline]
arch_do_signal_or_restart+0x4d8/0x800 arch/x86/kernel/signal.c:312
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xee/0x180 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+0x61/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc8159ba450
Code: 83 c0 16 83 e0 f7 74 12 50 48 8d 3d 22 1f 09 00 e8 e5 65 f9 ff 0f 1f 44 00 00 c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 <83> ff 21 74 0b c3 66 2e 0f 1f 84 00 00 00 00 00 55 53 48 89 f3 48
RSP: 002b:00007fc8167b0a78 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 00007fc815c15fa0 RCX: 00007fc81599aeb9
RDX: 00007fc8167b0a80 RSI: 00007fc8167b0bb0 RDI: 0000000000000021
RBP: 00007fc815a08c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc815c16038 R14: 00007fc815c15fa0 R15: 00007ffe7256c698
sched: RT throttling activated