rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 1-...!: (1 GPs behind) idle=963c/1/0x4000000000000000 softirq=64321/64322 fqs=2
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5193/1:b..l
rcu: (detected by 0, t=10502 jiffies, g=64045, q=239 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 13293 Comm: syz.6.1827 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:variable_test_bit arch/x86/include/asm/bitops.h:222 [inline]
RIP: 0010:arch_test_bit arch/x86/include/asm/bitops.h:233 [inline]
RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
RIP: 0010:cpumask_test_cpu include/linux/cpumask.h:647 [inline]
RIP: 0010:cpu_online include/linux/cpumask.h:1227 [inline]
RIP: 0010:trace_hrtimer_start include/trace/events/timer.h:222 [inline]
RIP: 0010:debug_activate kernel/time/hrtimer.c:478 [inline]
RIP: 0010:enqueue_hrtimer+0x81/0x3a0 kernel/time/hrtimer.c:1081
Code: 00 00 e8 f2 67 12 00 45 89 fd 41 c1 ef 06 4a 8d 3c fd 70 f3 7d 8f be 08 00 00 00 e8 79 07 79 00 31 f6 4c 0f a3 2d ef 7d ce 0d <40> 0f 92 c5 40 0f 92 c6 bf 02 00 00 00 e8 bd 6a 12 00 40 84 ed 74
RSP: 0018:ffffc90000a08d08 EFLAGS: 00000047
RAX: ffffffff81af7501 RBX: ffff8880776f2ac0 RCX: ffffffff81af7577
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8f7df370
RBP: 0000000000000000 R08: ffffffff8f7df377 R09: 1ffffffff1efbe6e
R10: dffffc0000000000 R11: fffffbfff1efbe6f R12: dffffc0000000000
R13: 0000000000000001 R14: ffff8880b8728340 R15: 0000000000000000
FS: 00007ff3880096c0(0000) GS:ffff888125fb8000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd881f156c0 CR3: 0000000055796000 CR4: 00000000003526f0
Call Trace:
__run_hrtimer kernel/time/hrtimer.c:1794 [inline]
__hrtimer_run_queues+0x636/0xc70 kernel/time/hrtimer.c:1841
hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline]
__sysvec_apic_timer_interrupt+0x102/0x410 arch/x86/kernel/apic/apic.c:1062
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1056
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:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa8/0x110 kernel/locking/spinlock.c:194
Code: 74 05 e8 3b 14 6b f6 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4f f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 93 83 32 f6 65 8b 05 7c de 17 07 85 c0 74 40 48 c7 04 24 0e 36
RSP: 0018:ffffc9000b5e7b60 EFLAGS: 00000206
RAX: 3d800699da795900 RBX: 0000000000000a06 RCX: 3d800699da795900
RDX: 0000000000000007 RSI: ffffffff8d790e8f RDI: 0000000000000001
RBP: ffffc9000b5e7bf0 R08: ffffffff8f7df377 R09: 1ffffffff1efbe6e
R10: dffffc0000000000 R11: fffffbfff1efbe6f R12: dffffc0000000000
R13: ffff8880b8628240 R14: ffff8880b8628240 R15: 1ffff920016bcf6c
clock_was_set+0x63b/0x7c0 kernel/time/hrtimer.c:965
do_settimeofday64+0x3cb/0x5a0 kernel/time/timekeeping.c:1460
__do_sys_clock_settime kernel/time/posix-timers.c:1131 [inline]
__se_sys_clock_settime kernel/time/posix-timers.c:1115 [inline]
__x64_sys_clock_settime+0x24f/0x290 kernel/time/posix-timers.c:1115
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff38718f749
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:00007ff388009038 EFLAGS: 00000246 ORIG_RAX: 00000000000000e3
RAX: ffffffffffffffda RBX: 00007ff3873e5fa0 RCX: 00007ff38718f749
RDX: 0000000000000000 RSI: 0000200000000240 RDI: 0000000000000000
RBP: 00007ff387213f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff3873e6038 R14: 00007ff3873e5fa0 R15: 00007ffec0802028
task:udevd state:R running task stack:22728 pid:5193 tgid:5193 ppid:1 task_flags:0x400140 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5257 [inline]
__schedule+0x14bc/0x5030 kernel/sched/core.c:6864
preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7191
irqentry_exit+0x5d8/0x660 kernel/entry/common.c:216
asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:hlist_bl_first_rcu include/linux/rculist_bl.h:24 [inline]
RIP: 0010:__d_lookup+0x10d/0x780 fs/dcache.c:2428
Code: 05 54 08 27 0d 01 48 c7 c7 40 b2 79 8b be 65 03 00 00 48 c7 c2 80 b2 79 8b e8 ff ea 5d ff 49 89 de 49 c1 ee 03 43 80 3c 26 00 <74> 08 48 89 df e8 e9 a7 e7 ff 4c 8b 3b e8 71 35 1b 09 89 c5 31 ff
RSP: 0018:ffffc90003017a40 EFLAGS: 00000246
RAX: ffffffff8240d229 RBX: ffffc9000076ba30 RCX: ffff88807eda1e80
RDX: 0000000000000000 RSI: ffffffff8bbf7740 RDI: ffffffff8bbf7700
RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff8240d1e6
R10: 0000000000002e2e R11: 0000000000000000 R12: dffffc0000000000
R13: ffffffff8240d1e6 R14: 1ffff920000ed746 R15: 1ffff92000602f93
lookup_fast+0x84/0x5b0 fs/namei.c:1813
walk_component+0x55/0x400 fs/namei.c:2186
lookup_last fs/namei.c:2691 [inline]
path_lookupat+0x163/0x430 fs/namei.c:2715
filename_lookup+0x212/0x570 fs/namei.c:2744
do_readlinkat+0xd9/0x500 fs/stat.c:576
__do_sys_readlink fs/stat.c:613 [inline]
__se_sys_readlink fs/stat.c:610 [inline]
__x64_sys_readlink+0x7f/0x90 fs/stat.c:610
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1a9c5153a7
RSP: 002b:00007ffc31bc4838 EFLAGS: 00000246 ORIG_RAX: 0000000000000059
RAX: ffffffffffffffda RBX: 00007ffc31bc4d10 RCX: 00007f1a9c5153a7
RDX: 0000000000000400 RSI: 00007ffc31bc4840 RDI: 00007ffc31bc4d10
RBP: 00007ffc31bc4840 R08: 000055e200c24794 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000400
R13: 00000000000000fe R14: 000055e200acbbe0 R15: 00007ffc31bc5810
rcu: rcu_preempt kthread starved for 10498 jiffies! g64045 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:27168 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5257 [inline]
__schedule+0x14bc/0x5030 kernel/sched/core.c:6864
__schedule_loop kernel/sched/core.c:6946 [inline]
schedule+0x165/0x360 kernel/sched/core.c:6961
schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 9688 Comm: kworker/u8:5 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0xccf/0x12d0 kernel/smp.c:877
Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 6a 9c 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 15 98 0b 00 eb 38 f3 90 <42> 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 f9 97
RSP: 0018:ffffc9000b4af660 EFLAGS: 00000293
RAX: ffffffff81b64557 RBX: 1ffff110170e8129 RCX: ffff888030eadb80
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000b4af7e0 R08: ffffffff8f7df377 R09: 1ffffffff1efbe6e
R10: dffffc0000000000 R11: fffffbfff1efbe6f R12: ffff8880b8740948
R13: dffffc0000000000 R14: ffff8880b863bb00 R15: 0000000000000001
FS: 0000000000000000(0000) GS:ffff888125eb8000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b30d17ff8 CR3: 000000000dd38000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000001d6b DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1043
on_each_cpu include/linux/smp.h:71 [inline]
smp_text_poke_sync_each_cpu arch/x86/kernel/alternative.c:2711 [inline]
smp_text_poke_batch_finish+0x5f9/0x1130 arch/x86/kernel/alternative.c:2921
arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146
static_key_enable_cpuslocked+0x128/0x250 kernel/jump_label.c:210
static_key_enable+0x1a/0x20 kernel/jump_label.c:223
toggle_allocation_gate+0xad/0x240 mm/kfence/core.c:854
process_one_work+0x93a/0x15e0 kernel/workqueue.c:3261
process_scheduled_works kernel/workqueue.c:3344 [inline]
worker_thread+0x9b0/0xee0 kernel/workqueue.c:3425
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246