syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5831/3:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=12517, q=480 ncpus=2)
task:syz-executor    state:R  running task     stack:19664 pid:5831  tgid:5831  ppid:5815   task_flags:0x400140 flags:0x00000002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5378 [inline]
 __schedule+0x18bc/0x4c40 kernel/sched/core.c:6765
 preempt_schedule_irq+0xfb/0x1c0 kernel/sched/core.c:7087
 irqentry_exit+0x5e/0x90 kernel/entry/common.c:354
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_acquire+0x264/0x550 kernel/locking/lockdep.c:5855
Code: 2b 00 74 08 4c 89 f7 e8 9a c3 89 00 f6 44 24 61 02 0f 85 85 01 00 00 41 f7 c7 00 02 00 00 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 25 00 00 00 00 00 43 c7 44 25 09 00 00 00 00 43 c7 44 25
RSP: 0018:ffffc900042bfb60 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 1ffff92000857f78 RCX: ffff88807e6764e8
RDX: dffffc0000000000 RSI: ffffffff8c2ac600 RDI: ffffffff8c802ce0
RBP: ffffc900042bfca8 R08: ffffffff94517847 R09: 1ffffffff28a2f08
R10: dffffc0000000000 R11: fffffbfff28a2f09 R12: 1ffff92000857f74
R13: dffffc0000000000 R14: ffffc900042bfbc0 R15: 0000000000000246
 rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 rcu_read_lock include/linux/rcupdate.h:849 [inline]
 group_send_sig_info+0xa3/0x310 kernel/signal.c:1413
 kill_pid_info_type+0xfa/0x1f0 kernel/signal.c:1458
 kill_pid_info kernel/signal.c:1472 [inline]
 kill_proc_info+0xd6/0x180 kernel/signal.c:1479
 kill_something_info kernel/signal.c:1576 [inline]
 __do_sys_kill kernel/signal.c:3957 [inline]
 __se_sys_kill+0xc2/0x450 kernel/signal.c:3951
 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: 0033:0x7fe324f29567
RSP: 002b:00007ffd4a0ed858 EFLAGS: 00000217 ORIG_RAX: 000000000000003e
RAX: ffffffffffffffda RBX: 0000000000000065 RCX: 00007fe324f29567
RDX: 0000000000000289 RSI: 0000000000000009 RDI: 0000000000000065
RBP: 00007ffd4a0ed89c R08: 0000000026bdbfad R09: 0000000000000000
R10: 00007fe325e36038 R11: 0000000000000217 R12: 000000000000001a
R13: 0000000000000064 R14: 0000000000022bb2 R15: 00007ffd4a0ed8f0
 </TASK>
rcu: rcu_preempt kthread starved for 6854 jiffies! g12517 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:26104 pid:18    tgid:18    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5378 [inline]
 __schedule+0x18bc/0x4c40 kernel/sched/core.c:6765
 __schedule_loop kernel/sched/core.c:6842 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6857
 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+0x7a9/0x920 kernel/kthread.c:464
 ret_from_fork+0x4b/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:
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.14.0-rc7-syzkaller-00067-g76b6905c11fd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:native_irq_disable arch/x86/include/asm/irqflags.h:37 [inline]
RIP: 0010:arch_local_irq_disable arch/x86/include/asm/irqflags.h:92 [inline]
RIP: 0010:acpi_safe_halt+0x21/0x30 drivers/acpi/processor_idle.c:112
Code: 90 90 90 90 90 90 90 90 90 65 48 8b 04 25 00 d5 03 00 48 f7 00 08 00 00 00 75 10 66 90 0f 00 2d 65 6e 88 00 f3 0f 1e fa fb f4 <fa> c3 cc cc cc cc 66 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90
RSP: 0018:ffffffff8e807ca8 EFLAGS: 00000246
RAX: ffffffff8e896580 RBX: ffff888145680064 RCX: 000000000017b819
RDX: 0000000000000001 RSI: ffff888145680000 RDI: ffff888145680064
RBP: 000000000003a938 R08: ffff8880b863799b R09: 1ffff110170c6f33
R10: dffffc0000000000 R11: ffffffff8c015010 R12: ffff888145ed2000
R13: 0000000000000001 R14: 0000000000000001 R15: ffffffff8f3261a0
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd846211d56 CR3: 00000000589aa000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 </IRQ>
 <TASK>
 acpi_idle_enter+0xe4/0x140 drivers/acpi/processor_idle.c:699
 cpuidle_enter_state+0x109/0x470 drivers/cpuidle/cpuidle.c:268
 cpuidle_enter+0x5d/0xa0 drivers/cpuidle/cpuidle.c:389
 call_cpuidle kernel/sched/idle.c:155 [inline]
 cpuidle_idle_call kernel/sched/idle.c:230 [inline]
 do_idle+0x372/0x5c0 kernel/sched/idle.c:325
 cpu_startup_entry+0x42/0x60 kernel/sched/idle.c:423
 rest_init+0x2dc/0x300 init/main.c:743
 start_kernel+0x484/0x510 init/main.c:1099
 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:515
 x86_64_start_kernel+0x66/0x70 arch/x86/kernel/head64.c:496
 common_startup_64+0x13e/0x147
 </TASK>