syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P7631/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=16413, q=2595 ncpus=2)
task:syz.4.626       state:R  running task     stack:23704 pid:7631  tgid:7629  ppid:5825   task_flags:0x400140 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5377 [inline]
 __schedule+0x190e/0x4c90 kernel/sched/core.c:6764
 preempt_schedule_common+0x84/0xd0 kernel/sched/core.c:6943
 preempt_schedule+0xe1/0xf0 kernel/sched/core.c:6967
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk.S:12
 __local_bh_enable_ip+0x179/0x200 kernel/softirq.c:396
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 xdp_test_run_batch net/bpf/test_run.c:368 [inline]
 bpf_test_run_xdp_live+0x1cd1/0x2230 net/bpf/test_run.c:390
 bpf_prog_test_run_xdp+0x805/0x11e0 net/bpf/test_run.c:1319
 bpf_prog_test_run+0x2e6/0x360 kernel/bpf/syscall.c:4406
 __sys_bpf+0x48d/0x810 kernel/bpf/syscall.c:5812
 __do_sys_bpf kernel/bpf/syscall.c:5901 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5899 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5899
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fca8158cda9
RSP: 002b:00007fca82327038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007fca817a5fa0 RCX: 00007fca8158cda9
RDX: 0000000000000048 RSI: 0000000020000600 RDI: 000000000000000a
RBP: 00007fca8160e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fca817a5fa0 R15: 00007ffec2410c68
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10485 jiffies! g16413 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=6778
rcu: rcu_preempt kthread starved for 10486 jiffies! g16413 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:25848 pid:17    tgid:17    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5377 [inline]
 __schedule+0x190e/0x4c90 kernel/sched/core.c:6764
 __schedule_loop kernel/sched/core.c:6841 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6856
 schedule_timeout+0x15a/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x2df/0x1330 kernel/rcu/tree.c:2024
 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2226
 kthread+0x7ab/0x920 kernel/kthread.c:464
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 7627 Comm: syz.1.625 Not tainted 6.13.0-syzkaller-09522-gd3d90cc2891c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
RIP: 0010:kasan_check_range+0x7/0x290 mm/kasan/generic.c:188
Code: ff 92 e3 ff 90 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 0f 1f 00 55 41 57 <41> 56 41 54 53 b0 01 48 85 f6 0f 84 a0 01 00 00 4c 8d 04 37 49 39
RSP: 0018:ffffc900000078d8 EFLAGS: 00000046
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff819adf3c
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff942f6840
RBP: 00000000000c4000 R08: 0000000000000001 R09: 0000000000000001
R10: dffffc0000000000 R11: fffffbfff20367ef R12: ffff88802e100ad4
R13: 0000000000000019 R14: 0000000000000000 R15: 0000000000000000
FS:  00007f3934b936c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000200f7000 CR3: 0000000028d40000 CR4: 0000000000350ef0
Call Trace:
 <NMI>
 </NMI>
 <IRQ>
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 hlock_class kernel/locking/lockdep.c:230 [inline]
 check_wait_context kernel/locking/lockdep.c:4852 [inline]
 __lock_acquire+0x4ac/0x2100 kernel/locking/lockdep.c:5178
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
 debug_object_activate+0x17f/0x580 lib/debugobjects.c:818
 debug_hrtimer_activate kernel/time/hrtimer.c:428 [inline]
 debug_activate kernel/time/hrtimer.c:469 [inline]
 enqueue_hrtimer+0x30/0x3c0 kernel/time/hrtimer.c:1075
 __run_hrtimer kernel/time/hrtimer.c:1755 [inline]
 __hrtimer_run_queues+0x6cb/0xd30 kernel/time/hrtimer.c:1802
 hrtimer_interrupt+0x403/0xa40 kernel/time/hrtimer.c:1864
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline]
 __sysvec_apic_timer_interrupt+0x112/0x420 arch/x86/kernel/apic/apic.c:1055
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1049
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:process_output_block drivers/tty/n_tty.c:539 [inline]
RIP: 0010:n_tty_write+0xa9a/0x1230 drivers/tty/n_tty.c:2389
Code: 93 55 fc 4c 89 e8 48 c1 e8 03 49 bf 00 00 00 00 00 fc ff df 42 0f b6 04 38 84 c0 0f 85 eb 01 00 00 41 ff 45 00 4c 8b 64 24 18 <44> 39 b4 24 b8 00 00 00 0f 84 33 02 00 00 e8 93 93 55 fc 49 ff c6
RSP: 0018:ffffc9001dc1faa0 EFLAGS: 00000246
RAX: ffffffff8569d8b5 RBX: 0000000000000000 RCX: 0000000000080000
RDX: ffffc9000be21000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: ffffc9001dc1fc38 R08: ffffffff8569d6ef R09: ffffffff8569d5cf
R10: 0000000000000004 R11: ffff88802e100000 R12: 0000000000000800
R13: ffffc9001dc05278 R14: 000000000000014b R15: dffffc0000000000
 iterate_tty_write drivers/tty/tty_io.c:1015 [inline]
 file_tty_write+0x548/0x9b0 drivers/tty/tty_io.c:1090
 new_sync_write fs/read_write.c:586 [inline]
 vfs_write+0xad1/0xd10 fs/read_write.c:679
 ksys_write+0x18f/0x2b0 fs/read_write.c:731
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3933d8cda9
Code: 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 01 48
RSP: 002b:00007f3934b93038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f3933fa5fa0 RCX: 00007f3933d8cda9
RDX: 0000000020002046 RSI: 0000000020001040 RDI: 0000000000000004
RBP: 00007f3933e0e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f3933fa5fa0 R15: 00007fff34278e58
 </TASK>