syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (0 ticks this GP) idle=8764/1/0x4000000000000000 softirq=51586/51586 fqs=0
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P11416/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=41249, q=232 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 5822 Comm: syz-executor Not tainted 6.16.0-rc4-syzkaller-00013-g66701750d556 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:arch_irqs_disabled_flags arch/x86/include/asm/irqflags.h:146 [inline]
RIP: 0010:arch_irqs_disabled arch/x86/include/asm/irqflags.h:153 [inline]
RIP: 0010:lock_release+0x29a/0x3e0 kernel/locking/lockdep.c:5895
Code: c7 e7 a5 b5 8d e8 d6 ce c1 09 b8 ff ff ff ff 65 0f c1 05 e9 cb fb 10 83 f8 01 75 51 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 <f7> 44 24 20 00 02 00 00 75 56 f7 c3 00 02 00 00 74 01 fb 65 48 8b
RSP: 0018:ffffc90000007bf8 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 0000000000000006 RCX: ea00c0f9a5e5db00
RDX: 0000000000000004 RSI: ffffffff8db5a5e7 RDI: ffffffff8be1b940
RBP: ffff888011b5c790 R08: ffff88805b4b6487 R09: 1ffff1100b696c90
R10: dffffc0000000000 R11: ffffed100b696c91 R12: 0000000000000004
R13: 0000000000000004 R14: ffff88807d1ef300 R15: ffff888011b5bc00
FS:  0000555574fa3500(0000) GS:ffff888125c84000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3458580ab8 CR3: 0000000078b68000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 __raw_spin_unlock include/linux/spinlock_api_smp.h:141 [inline]
 _raw_spin_unlock+0x16/0x50 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 advance_sched+0x99f/0xc90 net/sched/sch_taprio.c:981
 __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+0x10b/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:unwind_next_frame+0x1a8/0x2390 arch/x86/kernel/unwind_orc.c:494
Code: 4c 89 64 24 20 4c 89 7c 24 48 48 89 5c 24 10 0f b6 1b 48 8b 44 24 30 80 3c 28 00 4c 8b 7c 24 18 74 08 4c 89 ff e8 a8 19 af 00 <4d> 8b 27 48 83 f3 01 48 c7 c2 20 3e 88 8b 49 29 dc 0f 84 a2 01 00
RSP: 0018:ffffc9000446f4f8 EFLAGS: 00000246
RAX: 1ffff9200088dec2 RBX: 0000000000000000 RCX: ea00c0f9a5e5db00
RDX: 0000000000000000 RSI: ffffffff8be1b920 RDI: ffffffff8be1b8e0
RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffffff81728af5
R10: ffffc9000446f618 R11: ffffffff81ace5d0 R12: 1ffff9200088deb9
R13: ffffc9000446f618 R14: ffffc9000446f5c8 R15: ffffc9000446f610
 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:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4328 [inline]
 __kmalloc_noprof+0x27a/0x4f0 mm/slub.c:4340
 kmalloc_noprof include/linux/slab.h:909 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 tomoyo_encode2 security/tomoyo/realpath.c:45 [inline]
 tomoyo_encode+0x28b/0x550 security/tomoyo/realpath.c:80
 tomoyo_realpath_from_path+0x58d/0x5d0 security/tomoyo/realpath.c:283
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x213/0x4b0 security/tomoyo/file.c:822
 tomoyo_path_rmdir+0xa2/0xe0 security/tomoyo/tomoyo.c:195
 security_path_rmdir+0x167/0x360 security/security.c:1949
 do_rmdir+0x219/0x630 fs/namei.c:4522
 __do_sys_unlinkat fs/namei.c:4699 [inline]
 __se_sys_unlinkat fs/namei.c:4693 [inline]
 __x64_sys_unlinkat+0xc2/0xf0 fs/namei.c:4693
 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: 0033:0x7fe49df8df07
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 07 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:00007ffe434aec48 EFLAGS: 00000207 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 0000000000000065 RCX: 00007fe49df8df07
RDX: 0000000000000200 RSI: 00007ffe434afd90 RDI: 00000000ffffff9c
RBP: 00007fe49e010925 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000207 R12: 00007ffe434afd90
R13: 00007fe49e010925 R14: 000000000009279a R15: 00007ffe434afdd0
 </TASK>
task:syz.0.1423      state:R  running task     stack:27112 pid:11416 tgid:11405 ppid:5819   task_flags:0x400040 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5396 [inline]
 __schedule+0x16a2/0x4cb0 kernel/sched/core.c:6785
 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7108
 irqentry_exit+0x6f/0x90 kernel/entry/common.c:307
 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:707
RIP: 0010:lock_acquire+0x175/0x360 kernel/locking/lockdep.c:5875
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 9e fb 10 <48> 3b 44 24 58 0f 85 f2 00 00 00 48 83 c4 60 5b 41 5c 41 5d 41 5e
RSP: 0000:ffffc9000b5ff7c0 EFLAGS: 00000206
RAX: dc0397b802991f00 RBX: 0000000000000000 RCX: dc0397b802991f00
RDX: 0000000000000000 RSI: ffffffff8db5a5e7 RDI: ffffffff8be1b940
RBP: ffffffff8238c5b0 R08: 0000000000000000 R09: ffffffff8238c5b0
R10: dffffc0000000000 R11: ffffed100ff09a7b R12: 0000000000000002
R13: ffffffff8e13ee20 R14: 0000000000000000 R15: 0000000000000246
 rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 rcu_read_lock include/linux/rcupdate.h:841 [inline]
 d_alloc_parallel+0x301/0x14e0 fs/dcache.c:2541
 __lookup_slow+0x116/0x3d0 fs/namei.c:1802
 start_creating+0x22e/0x3c0 fs/debugfs/inode.c:391
 __debugfs_create_file+0x79/0x4f0 fs/debugfs/inode.c:437
 debugfs_create_file_full+0x3f/0x60 fs/debugfs/inode.c:474
 kvm_create_vm_debugfs+0x6b6/0x900 virt/kvm/kvm_main.c:1076
 kvm_create_vm virt/kvm/kvm_main.c:1204 [inline]
 kvm_dev_ioctl_create_vm virt/kvm/kvm_main.c:5472 [inline]
 kvm_dev_ioctl+0x1516/0x18e0 virt/kvm/kvm_main.c:5514
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893
 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: 0033:0x7f417f98e929
RSP: 002b:00007f4180839038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f417fbb6160 RCX: 00007f417f98e929
RDX: 0000000000000000 RSI: 000000000000ae01 RDI: 0000000000000008
RBP: 00007f417fa10b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f417fbb6160 R15: 00007ffeb0b75f18
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g41249 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=34206
rcu: rcu_preempt kthread starved for 10502 jiffies! g41249 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27320 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5396 [inline]
 __schedule+0x16a2/0x4cb0 kernel/sched/core.c:6785
 __schedule_loop kernel/sched/core.c:6863 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6878
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2054
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2256
 kthread+0x711/0x8a0 kernel/kthread.c:464
 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>