syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (2 GPs behind) idle=f884/1/0x4000000000000000 softirq=19498/19499 fqs=0
rcu: 	(detected by 1, t=10506 jiffies, g=12645, q=482 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6123 Comm: syz-executor Not tainted 6.16.0-syzkaller-12126-g4faff70959d5 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:__kasan_check_write+0x0/0x20 mm/kasan/shadow.c:36
Code: 48 8b 0c 24 31 d2 e9 ef e4 ff ff 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 89 f6 48 8b 0c 24 ba 01 00 00 00 e9 bc e4 ff ff 66 66
RSP: 0018:ffffc90000007b78 EFLAGS: 00000006
RAX: ffffffff8961234f RBX: ffff88807bff2000 RCX: ffff88807b751e00
RDX: 0000000000010000 RSI: 0000000000000008 RDI: ffff88807bff2158
RBP: ffffc90000007c60 R08: 0000000000000000 R09: ffffffff8999e108
R10: dffffc0000000000 R11: ffffed100f7fe45e R12: ffff88807bff2360
R13: 1ffff92000000f74 R14: 0000001a7e218aaa R15: ffff888028053c00
FS:  0000555582e7b500(0000) GS:ffff888125c21000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f623224f524 CR3: 00000000314c2000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
 test_and_set_bit include/asm-generic/bitops/instrumented-atomic.h:71 [inline]
 __netif_schedule+0x90/0x2c0 net/core/dev.c:3376
 advance_sched+0xa9a/0xc90 net/sched/sch_taprio.c:991
 __run_hrtimer kernel/time/hrtimer.c:1761 [inline]
 __hrtimer_run_queues+0x52c/0xc60 kernel/time/hrtimer.c:1825
 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline]
 __sysvec_apic_timer_interrupt+0x108/0x410 arch/x86/kernel/apic/apic.c:1056
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1050
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+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 eb 93 02 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:ffffc9000215f518 EFLAGS: 00000206
RAX: 7d5c578cb173b200 RBX: 0000000000000000 RCX: 7d5c578cb173b200
RDX: 0000000000000000 RSI: ffffffff8dba39c2 RDI: ffffffff8be32680
RBP: ffffffff8172c195 R08: 0000000000000000 R09: ffffffff8172c195
R10: ffffc9000215f6e8 R11: fffff5200042bee9 R12: 0000000000000002
R13: ffffffff8e139ee0 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:1155 [inline]
 unwind_next_frame+0xc2/0x2390 arch/x86/kernel/unwind_orc.c:479
 __unwind_start+0x5b9/0x760 arch/x86/kernel/unwind_orc.c:758
 unwind_start arch/x86/include/asm/unwind.h:64 [inline]
 arch_stack_walk+0xe4/0x150 arch/x86/kernel/stacktrace.c:24
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:243 [inline]
 __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:275
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2417 [inline]
 slab_free mm/slub.c:4680 [inline]
 kfree+0x18e/0x440 mm/slub.c:4879
 tomoyo_path_perm+0x3a2/0x4b0 security/tomoyo/file.c:842
 tomoyo_path_symlink+0xa3/0xe0 security/tomoyo/tomoyo.c:212
 security_path_symlink+0x177/0x380 security/security.c:1984
 do_symlinkat+0x107/0x3f0 fs/namei.c:4754
 __do_sys_symlinkat fs/namei.c:4772 [inline]
 __se_sys_symlinkat fs/namei.c:4769 [inline]
 __x64_sys_symlinkat+0x95/0xb0 fs/namei.c:4769
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f623218e167
Code: 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 0a 01 00 00 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:00007fff284e58b8 EFLAGS: 00000206 ORIG_RAX: 000000000000010a
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f623218e167
RDX: 00007f62322136c4 RSI: 00000000ffffff9c RDI: 00007fff284e5950
RBP: 00007fff284e58fc R08: 0000000000000017 R09: 00007fff284e5607
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000001
R13: 00000000000927c0 R14: 000000000001b05e R15: 00007fff284e5950
 </TASK>
rcu: rcu_preempt kthread starved for 10506 jiffies! g12645 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:27160 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 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+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 1107 Comm: kworker/u8:6 Not tainted 6.16.0-syzkaller-12126-g4faff70959d5 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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 b6 62 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 61 5e 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 45 5e
RSP: 0018:ffffc90003bff660 EFLAGS: 00000293
RAX: ffffffff81b44d6b RBX: 1ffff110170c8341 RCX: ffff888026cb3c00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90003bff7e0 R08: ffffffff8fa34737 R09: 1ffffffff1f468e6
R10: dffffc0000000000 R11: fffffbfff1f468e7 R12: ffff8880b8641a08
R13: dffffc0000000000 R14: ffff8880b873b1c0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888125d21000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c007fac000 CR3: 000000000df36000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 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:2653 [inline]
 smp_text_poke_batch_finish+0x5f9/0x1130 arch/x86/kernel/alternative.c:2863
 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:850
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>