rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-...!: (1 GPs behind) idle=e3ac/1/0x4000000000000000 softirq=69928/69929 fqs=0
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P12705/1:b..l
rcu: (detected by 1, t=10502 jiffies, g=66981, q=100 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 51 Comm: kworker/0:1H Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: events_highpri snd_vmidi_output_work
RIP: 0010:hlock_class kernel/locking/lockdep.c:229 [inline]
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4879 [inline]
RIP: 0010:__lock_acquire+0x4ff/0xd20 kernel/locking/lockdep.c:5187
Code: 44 89 e0 48 ff c3 48 63 8f 28 0b 00 00 49 83 c7 28 41 89 c4 48 39 cb 0f 8d d6 00 00 00 48 83 fb 31 0f 83 92 00 00 00 41 8b 07 <25> ff 1f 00 00 48 0f a3 05 14 df 2d 12 73 10 48 69 c0 c8 00 00 00
RSP: 0018:ffffc90000007ab0 EFLAGS: 00000087
RAX: 00000000000c406e RBX: 0000000000000002 RCX: 0000000000084965
RDX: 0000000000000002 RSI: 0000000000004000 RDI: ffff888022af1e40
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff84d4b10b
R10: ffffc90000007ca0 R11: fffff52000000f96 R12: 0000000000000002
R13: 0000000000000002 R14: ffff888022af29e8 R15: ffff888022af29e0
FS: 0000000000000000(0000) GS:ffff8881259e8000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000003000 CR3: 000000005a392000 CR4: 00000000003526f0
Call Trace:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
debug_object_activate+0xbb/0x420 lib/debugobjects.c:818
debug_hrtimer_activate kernel/time/hrtimer.c:438 [inline]
debug_activate kernel/time/hrtimer.c:477 [inline]
enqueue_hrtimer+0x30/0x3a0 kernel/time/hrtimer.c:1081
__run_hrtimer kernel/time/hrtimer.c:1794 [inline]
__hrtimer_run_queues+0x656/0xc60 kernel/time/hrtimer.c:1841
hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1041 [inline]
__sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1058
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1052
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:finish_task_switch+0x26b/0x950 kernel/sched/core.c:5228
Code: 0f 84 3c 01 00 00 48 85 db 0f 85 63 01 00 00 e9 27 05 00 00 4c 8b 75 d0 4c 89 e7 e8 ff 81 f4 09 e8 7a 4c 36 00 fb 4c 8b 65 c0 <49> 8d bc 24 58 16 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0018:ffffc90000bb7518 EFLAGS: 00000286
RAX: c1c495e448be7d00 RBX: 0000000000000000 RCX: c1c495e448be7d00
RDX: 0000000000000006 RSI: ffffffff8dbbd648 RDI: ffffffff8c036f00
RBP: ffffc90000bb7570 R08: ffffffff8fc3f337 R09: 1ffffffff1f87e66
R10: dffffc0000000000 R11: fffffbfff1f87e67 R12: ffff888022af1e40
R13: dffffc0000000000 R14: ffff88807c9e1e40 R15: ffff8880b863ab58
context_switch kernel/sched/core.c:5363 [inline]
__schedule+0x17a0/0x4cc0 kernel/sched/core.c:6964
preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7148
preempt_schedule+0xae/0xc0 kernel/sched/core.c:7172
preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
_raw_spin_unlock_irqrestore+0xfd/0x110 kernel/locking/spinlock.c:194
spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
class_spinlock_irqsave_destructor include/linux/spinlock.h:585 [inline]
snd_rawmidi_transmit+0xc9/0x100 sound/core/rawmidi.c:1493
snd_vmidi_output_work+0x1a3/0x410 sound/core/seq/seq_virmidi.c:151
process_one_work kernel/workqueue.c:3263 [inline]
process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
task:syz.0.1205 state:R running task stack:21736 pid:12705 tgid:12688 ppid:5868 task_flags:0x400940 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:5360 [inline]
__schedule+0x1798/0x4cc0 kernel/sched/core.c:6964
preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7291
irqentry_exit+0x6f/0x90 kernel/entry/common.c:211
asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_acquire+0x175/0x360 kernel/locking/lockdep.c:5872
Code: 00 00 00 00 9c 8f 44 24 30 f7 44 24 30 00 02 00 00 0f 85 cd 00 00 00 f7 44 24 08 00 02 00 00 74 01 fb 65 48 8b 05 0b 23 26 11 <48> 3b 44 24 58 0f 85 f2 00 00 00 48 83 c4 60 5b 41 5c 41 5d 41 5e
RSP: 0018:ffffc90003775fb8 EFLAGS: 00000206
RAX: 853f214ca509d200 RBX: 0000000000000000 RCX: 853f214ca509d200
RDX: 0000000000000000 RSI: ffffffff8ddae1af RDI: ffffffff8c036f00
RBP: ffffffff8173bd25 R08: 0000000000000000 R09: ffffffff8173bd25
R10: ffffc90003776178 R11: ffffffff81ac3160 R12: 0000000000000002
R13: ffffffff8e33c820 R14: 0000000000000000 R15: 0000000000000246
rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
rcu_read_lock include/linux/rcupdate.h:841 [inline]
class_rcu_constructor include/linux/rcupdate.h:1169 [inline]
unwind_next_frame+0xc2/0x2390 arch/x86/kernel/unwind_orc.c:479
arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:56 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
unpoison_slab_object mm/kasan/common.c:339 [inline]
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:365
kasan_slab_alloc include/linux/kasan.h:250 [inline]
slab_post_alloc_hook mm/slub.c:4770 [inline]
slab_alloc_node mm/slub.c:5068 [inline]
kmem_cache_alloc_noprof+0x367/0x6e0 mm/slub.c:5075
cache_alloc_zspage mm/zsmalloc.c:420 [inline]
alloc_zspage+0xd0/0xbc0 mm/zsmalloc.c:968
zs_malloc+0x3e3/0x720 mm/zsmalloc.c:1300
zswap_compress mm/zswap.c:910 [inline]
zswap_store_page mm/zswap.c:1429 [inline]
zswap_store+0x1062/0x1f40 mm/zswap.c:1540
swap_writeout+0x710/0xd70 mm/page_io.c:275
writeout mm/vmscan.c:662 [inline]
pageout mm/vmscan.c:721 [inline]
shrink_folio_list+0x3011/0x4c70 mm/vmscan.c:1453
reclaim_folio_list+0xeb/0x500 mm/vmscan.c:2233
reclaim_pages+0x454/0x520 mm/vmscan.c:2270
madvise_cold_or_pageout_pte_range+0x1974/0x1d00 mm/madvise.c:566
walk_pmd_range mm/pagewalk.c:130 [inline]
walk_pud_range mm/pagewalk.c:224 [inline]
walk_p4d_range mm/pagewalk.c:262 [inline]
walk_pgd_range+0xfe9/0x1d40 mm/pagewalk.c:303
__walk_page_range+0x14c/0x710 mm/pagewalk.c:410
walk_page_range_vma+0x393/0x440 mm/pagewalk.c:705
madvise_pageout_page_range mm/madvise.c:625 [inline]
madvise_pageout mm/madvise.c:650 [inline]
madvise_vma_behavior+0x311f/0x3a10 mm/madvise.c:1354
madvise_walk_vmas+0x51c/0xa30 mm/madvise.c:1671
madvise_do_behavior+0x38e/0x550 mm/madvise.c:1887
do_madvise+0x1bc/0x270 mm/madvise.c:1980
__do_sys_madvise mm/madvise.c:1989 [inline]
__se_sys_madvise mm/madvise.c:1987 [inline]
__x64_sys_madvise+0xa7/0xc0 mm/madvise.c:1987
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: 0033:0x7f6122f8eba9
RSP: 002b:00007f6123e79038 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007f61231d6090 RCX: 00007f6122f8eba9
RDX: 0000000000000015 RSI: 7fffffffffffffff RDI: 0000200000000000
RBP: 00007f6123011e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f61231d6128 R14: 00007f61231d6090 R15: 00007ffd5f34fd98
rcu: rcu_preempt kthread starved for 10502 jiffies! g66981 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:26664 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:5360 [inline]
__schedule+0x1798/0x4cc0 kernel/sched/core.c:6964
__schedule_loop kernel/sched/core.c:7046 [inline]
schedule+0x165/0x360 kernel/sched/core.c:7061
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+0x4bc/0x870 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: 1 UID: 0 PID: 8011 Comm: kworker/u8:12 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0xd33/0x12d0 kernel/smp.c:877
Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 16 7c 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 c1 77 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 a5 77
RSP: 0018:ffffc90019d8f640 EFLAGS: 00000293
RAX: ffffffff81b443cb RBX: 1ffff110170c8355 RCX: ffff88802d431e40
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90019d8f7c0 R08: ffffffff8fc3f337 R09: 1ffffffff1f87e66
R10: dffffc0000000000 R11: fffffbfff1f87e67 R12: ffff8880b8641aa8
R13: dffffc0000000000 R14: ffff8880b873b1c0 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888125ae8000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000100 CR3: 000000000e138000 CR4: 00000000003526f0
Call Trace:
on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1044
on_each_cpu include/linux/smp.h:71 [inline]
smp_text_poke_sync_each_cpu arch/x86/kernel/alternative.c:2713 [inline]
smp_text_poke_batch_finish+0x5f9/0x1130 arch/x86/kernel/alternative.c:2923
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:852
process_one_work kernel/workqueue.c:3263 [inline]
process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245