rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 1-...!: (1 GPs behind) idle=dbec/1/0x4000000000000000 softirq=45996/45999 fqs=0
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4987/1:b..l
rcu: (detected by 0, t=10502 jiffies, g=56301, q=241 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 23 Comm: ksoftirqd/1 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:lockdep_recursion_inc kernel/locking/lockdep.c:465 [inline]
RIP: 0010:lock_acquire+0xc1/0x350 kernel/locking/lockdep.c:5867
Code: 11 85 c0 0f 85 bf 00 00 00 65 48 8b 05 30 da 97 11 83 b8 8c 0b 00 00 00 0f 85 aa 00 00 00 4c 89 74 24 10 4d 89 fe 9c 41 5f fa <48> c7 c7 51 6a fc 8d e8 93 ab 07 0a 65 ff 05 ac 1f 98 11 45 31 c9
RSP: 0018:ffffc90000a08460 EFLAGS: 00000046
RAX: ffff88801dae0000 RBX: 0000000000000000 RCX: 0000000080010104
RDX: 0000000000000000 RSI: ffffffff8babee80 RDI: 1ffffffff34d30e2
RBP: ffffffff84bce2dc R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed100aa0f863 R12: 0000000000000000
R13: ffffffff9a698710 R14: 0000000000000001 R15: 0000000000000046
FS: 0000000000000000(0000) GS:ffff888125387000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0826885000 CR3: 000000001ff04000 CR4: 0000000000350ef0
Call Trace:
__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+0x52/0xc0 arch/x86/kernel/apic/apic.c:1061
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_acquire+0x221/0x350 kernel/locking/lockdep.c:5872
Code: ff ff ff e8 f1 8d 07 0a f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 db d8 97 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 ab 89 6e ff cc 48 8d 3d 88 7c 92
RSP: 0018:ffffc90000a08858 EFLAGS: 00000282
RAX: f2c01cbef8398200 RBX: 0000000000000000 RCX: 0000000080000101
RDX: 0000000044627c0b RSI: ffffffff8e22037a RDI: ffffffff8c28b660
RBP: ffffffff8176f256 R08: ffffffff8176f256 R09: ffffffff8e95cca0
R10: dffffc0000000000 R11: ffffffff81b0f020 R12: 0000000000000002
R13: ffffffff8e95cca0 R14: 0000000000000000 R15: 0000000000000246
rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
rcu_read_lock include/linux/rcupdate.h:838 [inline]
class_rcu_constructor include/linux/rcupdate.h:1181 [inline]
unwind_next_frame+0xc3/0x2550 arch/x86/kernel/unwind_orc.c:495
arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2689 [inline]
slab_free mm/slub.c:6251 [inline]
kfree+0x1c5/0x640 mm/slub.c:6566
slab_free_after_rcu_debug+0x62/0x220 mm/slub.c:6300
rcu_do_batch kernel/rcu/tree.c:2617 [inline]
rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
handle_softirqs+0x22a/0x840 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1061
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:finish_task_switch+0x427/0xbe0 kernel/sched/core.c:5245
Code: 41 c7 84 24 e0 0d 00 00 00 00 00 00 0f 1f 44 00 00 49 83 c4 48 4c 89 e7 e8 16 f8 16 0a e8 f1 fa 38 00 fb 49 8d bd b0 16 00 00 <48> 89 f8 48 c1 e8 03 42 0f b6 04 38 84 c0 0f 85 7b 03 00 00 41 80
RSP: 0018:ffffc900001d7ab0 EFLAGS: 00000202
RAX: 0000000000307513 RBX: 1ffff110170e7784 RCX: 0000000080000001
RDX: 0000000000000000 RSI: ffffffff8dfacd65 RDI: ffff88801dae16b0
RBP: ffffc900001d7b10 R08: ffffffff9030d5f7 R09: 1ffffffff2061abe
R10: dffffc0000000000 R11: fffffbfff2061abf R12: ffff8880b873ae88
R13: ffff88801dae0000 R14: ffff88807d4c9ec0 R15: dffffc0000000000
context_switch kernel/sched/core.c:5391 [inline]
__schedule+0x1829/0x5740 kernel/sched/core.c:7189
__schedule_loop kernel/sched/core.c:7268 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7283
smpboot_thread_fn+0x5bc/0xa50 kernel/smpboot.c:156
kthread+0x389/0x470 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
task:udevd state:R running task stack:22568 pid:4987 tgid:4987 ppid:1 task_flags:0x400140 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5388 [inline]
__schedule+0x1821/0x5740 kernel/sched/core.c:7189
preempt_schedule_notrace+0x57/0x90 kernel/sched/core.c:7463
preempt_schedule_notrace_thunk+0x16/0x30 arch/x86/entry/thunk.S:13
rcu_is_watching+0x7f/0xb0 kernel/rcu/tree.c:753
rcu_read_lock include/linux/rcupdate.h:839 [inline]
class_rcu_constructor include/linux/rcupdate.h:1181 [inline]
unwind_next_frame+0xd5/0x2550 arch/x86/kernel/unwind_orc.c:495
arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0xa9/0x100 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:4570 [inline]
slab_alloc_node mm/slub.c:4899 [inline]
kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4906
alloc_filename fs/namei.c:142 [inline]
do_getname+0x2e/0x250 fs/namei.c:182
class_filename_flags_constructor include/linux/fs.h:2555 [inline]
do_readlinkat+0xc8/0x510 fs/stat.c:569
__do_sys_readlink fs/stat.c:605 [inline]
__se_sys_readlink fs/stat.c:602 [inline]
__x64_sys_readlink+0x7f/0x90 fs/stat.c:602
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: 0033:0x7f08261153a7
RSP: 002b:00007ffe1cec4098 EFLAGS: 00000246 ORIG_RAX: 0000000000000059
RAX: ffffffffffffffda RBX: 00007ffe1cec4570 RCX: 00007f08261153a7
RDX: 0000000000000400 RSI: 00007ffe1cec40a0 RDI: 00007ffe1cec4570
RBP: 00007ffe1cec40a0 R08: 0000000000000800 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000400
R13: 0000558d62275100 R14: 0000000000000000 R15: 00007ffe1cec4f90
rcu: rcu_preempt kthread starved for 10502 jiffies! g56301 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:5388 [inline]
__schedule+0x1821/0x5740 kernel/sched/core.c:7189
__schedule_loop kernel/sched/core.c:7268 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7283
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+0x389/0x470 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: 1349 Comm: kworker/u8:8 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0xfd4/0x13d0 kernel/smp.c:892
Code: 89 ee 83 e6 01 31 ff e8 7a 06 0c 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 25 02 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 02 0c 00 eb e5 44 89
RSP: 0018:ffffc900061a7700 EFLAGS: 00000293
RAX: 0000000000000000 RBX: ffff8880b863c148 RCX: ffff8880296cbd80
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900061a7840 R08: ffffffff9030d5f7 R09: 1ffffffff2061abe
R10: dffffc0000000000 R11: fffffbfff2061abf R12: 1ffff110170e8169
R13: dffffc0000000000 R14: ffff8880b8740b48 R15: 0000000000000001
FS: 0000000000000000(0000) GS:ffff888125287000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b34319ff8 CR3: 000000000e74a000 CR4: 0000000000350ef0
Call Trace:
on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1057
on_each_cpu include/linux/smp.h:72 [inline]
smp_text_poke_sync_each_cpu arch/x86/kernel/alternative.c:2773 [inline]
smp_text_poke_batch_finish+0x5f5/0x1160 arch/x86/kernel/alternative.c:2983
arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146
static_key_enable_cpuslocked+0x128/0x240 kernel/jump_label.c:210
static_key_enable+0x1a/0x20 kernel/jump_label.c:223
toggle_allocation_gate+0xab/0x290 mm/kfence/core.c:906
process_one_work kernel/workqueue.c:3314 [inline]
process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
kthread+0x389/0x470 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