syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P3027/1:b..l
	(detected by 0, t=10502 jiffies, g=5641, q=273)
task:udevd           state:R  running task     stack:24856 pid: 3027 ppid:     1 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5027 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6777
 irqentry_exit+0x53/0x80 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:native_irq_enable arch/x86/include/asm/irqflags.h:45 [inline]
RIP: 0010:arch_local_irq_enable arch/x86/include/asm/irqflags.h:80 [inline]
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/irqflags.h:140 [inline]
RIP: 0010:seqcount_lockdep_reader_access+0x1d2/0x220 include/linux/seqlock.h:105
Code: 5e e8 42 3e 9c ff 4d 85 f6 48 bb 00 00 00 00 00 fc ff df 75 07 e8 2e 3e 9c ff eb 06 e8 27 3e 9c ff fb 48 c7 04 24 0e 36 e0 45 <4a> c7 04 23 00 00 00 00 66 42 c7 44 23 09 00 00 42 c6 44 23 0b 00
RSP: 0018:ffffc90002337900 EFLAGS: 00000293
RAX: ffffffff81e42379 RBX: dffffc0000000000 RCX: ffff88807d361dc0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900023379b8 R08: ffffffff81e42354 R09: fffffbfff1bd2a56
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff92000466f20
R13: ffffc90002337920 R14: 0000000000000200 R15: 0000000000000046
 read_seqbegin include/linux/seqlock.h:840 [inline]
 read_seqbegin_or_lock include/linux/seqlock.h:1144 [inline]
 prepend_path+0xba/0xb70 fs/d_path.c:167
 d_absolute_path+0x175/0x300 fs/d_path.c:235
 tomoyo_get_absolute_path security/tomoyo/realpath.c:101 [inline]
 tomoyo_realpath_from_path+0x2fd/0x5e0 security/tomoyo/realpath.c:276
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_number_perm+0x225/0x810 security/tomoyo/file.c:723
 security_file_ioctl+0x6d/0xa0 security/security.c:1555
 __do_sys_ioctl fs/ioctl.c:868 [inline]
 __se_sys_ioctl+0x47/0x160 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f2ee6471d49
RSP: 002b:00007ffdeb286de8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f2ee6471d49
RDX: 0000000000000000 RSI: 000000000000125f RDI: 000000000000000c
RBP: 000055642ee8dea0 R08: 0000000000000008 R09: cdf4d5e7e8105474
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffdeb286fd8
R13: 000000000000000c R14: 000055642ea3efee R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 10533 jiffies! g5641 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:27064 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5027 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373
 schedule+0x11b/0x1f0 kernel/sched/core.c:6456
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x2bf/0x1080 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0xa4/0x360 kernel/rcu/tree.c:2145
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 0
CPU: 0 PID: 3806 Comm: syz.0.47 Not tainted 5.15.165-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x181/0x2a0 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_check_gp_kthread_starvation+0x1d2/0x240 kernel/rcu/tree_stall.h:487
 print_other_cpu_stall+0x137a/0x14d0 kernel/rcu/tree_stall.h:592
 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
 rcu_pending kernel/rcu/tree.c:3932 [inline]
 rcu_sched_clock_irq+0xa38/0x1150 kernel/rcu/tree.c:2619
 update_process_times+0x196/0x200 kernel/time/timer.c:1818
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x386/0x550 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1686 [inline]
 __hrtimer_run_queues+0x55b/0xcf0 kernel/time/hrtimer.c:1750
 hrtimer_interrupt+0x392/0x980 kernel/time/hrtimer.c:1812
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1085 [inline]
 __sysvec_apic_timer_interrupt+0x139/0x470 arch/x86/kernel/apic/apic.c:1102
 sysvec_apic_timer_interrupt+0x8c/0xb0 arch/x86/kernel/apic/apic.c:1096
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: a1 68 f6 ff 90 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 3e ee 25 f7 48 89 df e8 16 42 27 f7 e8 51 fd 49 f7 fb bf 01 00 00 00 <e8> f6 87 1a f7 65 8b 05 d7 8a c5 75 85 c0 74 02 5b c3 e8 a4 a7 c3
RSP: 0018:ffffc90003637bc0 EFLAGS: 00000282
RAX: 60776f965bcde500 RBX: ffff8880204c40c0 RCX: ffffffff91468f03
RDX: dffffc0000000000 RSI: ffffffff8a8b2a20 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffffffff8186e260 R09: ffffed1004098819
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000021
R13: dffffc0000000000 R14: ffff8880204c4558 R15: ffff8880204c40c0
 spin_unlock_irq include/linux/spinlock.h:413 [inline]
 get_signal+0x13ee/0x14e0 kernel/signal.c:2900
 arch_do_signal_or_restart+0xc3/0x1890 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0x97/0x130 kernel/entry/common.c:178
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x5d/0x240 kernel/entry/common.c:307
 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f75dc320e77
Code: ff ff 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
RSP: 002b:00007f75db5a50e8 EFLAGS: 00000246
RAX: 00000000000000ca RBX: 00007f75dc4bcf88 RCX: 00007f75dc320e79
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f75dc4bcf88
RBP: 00007f75dc4bcf80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f75dc4bcf8c
R13: 0000000000000000 R14: 00007ffe397a0bb0 R15: 00007ffe397a0c98
 </TASK>