rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10499 ticks this GP) idle=dcb/1/0x4000000000000000 softirq=6216/6216 fqs=5 
	(t=10501 jiffies g=6641 q=283)
rcu: rcu_preempt kthread starved for 10492 jiffies! g6641 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:28032 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1e0 kernel/sched/core.c:6459
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145
 kthread+0x436/0x520 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:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4311 Comm: syz.0.18 Not tainted 5.15.185-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:hlock_class kernel/locking/lockdep.c:192 [inline]
RIP: 0010:lookup_chain_cache_add kernel/locking/lockdep.c:3700 [inline]
RIP: 0010:validate_chain kernel/locking/lockdep.c:3756 [inline]
RIP: 0010:__lock_acquire+0x138c/0x7c60 kernel/locking/lockdep.c:5012
Code: 44 24 58 42 0f b6 04 00 84 c0 0f 85 98 57 00 00 4d 09 f4 41 8b 07 89 c1 81 e1 00 80 04 00 81 f9 00 00 04 00 0f 85 97 05 00 00 <89> c3 81 e3 ff 1f 00 00 c1 e8 03 25 f8 03 00 00 48 8d b8 c0 b0 f9
RSP: 0018:ffffc9000346f8a0 EFLAGS: 00000046
RAX: 000000000005019a RBX: ffffffff8f936340 RCX: 0000000000040000
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8ff9b0f0
RBP: ffffc9000346faf0 R08: dffffc0000000000 R09: fffffbfff1ff361f
R10: fffffbfff1ff361f R11: 1ffffffff1ff361e R12: bd79ce1d5ff75e59
R13: ffff888077833b80 R14: 000000005ff75e59 R15: ffff888077834690
FS:  00007fccff99a6c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000006b000 CR3: 0000000022098000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 __might_fault+0xb3/0x110 mm/memory.c:5357
 __clear_user arch/x86/lib/usercopy_64.c:20 [inline]
 clear_user+0xd2/0x150 arch/x86/lib/usercopy_64.c:54
 copy_siginfo_to_user+0x57/0x80 kernel/signal.c:3369
 __setup_rt_frame arch/x86/kernel/signal.c:490 [inline]
 setup_rt_frame arch/x86/kernel/signal.c:780 [inline]
 handle_signal arch/x86/kernel/signal.c:824 [inline]
 arch_do_signal_or_restart+0xd56/0x1300 arch/x86/kernel/signal.c:869
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0x9e/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+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fcd01b32927
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:00007fccff99a0e8 EFLAGS: 00000246
RAX: 00000000000000ca RBX: 00007fcd01d59fa8 RCX: 00007fcd01b32929
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fcd01d59fa8
RBP: 00007fcd01d59fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fcd01d59fac
R13: 0000000000000000 R14: 00007ffee3283850 R15: 00007ffee3283938
 </TASK>
NMI backtrace for cpu 0
sched: RT throttling activated
CPU: 0 PID: 4304 Comm: syz.3.15 Not tainted 5.15.185-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <IRQ>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_dump_cpu_stacks+0x22f/0x380 kernel/rcu/tree_stall.h:349
 print_cpu_stall+0x31d/0x5f0 kernel/rcu/tree_stall.h:633
 check_cpu_stall kernel/rcu/tree_stall.h:727 [inline]
 rcu_pending kernel/rcu/tree.c:3932 [inline]
 rcu_sched_clock_irq+0x6d8/0x1110 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:1818
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1690 [inline]
 __hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1754
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lock_acquire+0x1f2/0x3f0 kernel/locking/lockdep.c:5627
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f6 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b
RSP: 0018:ffffc900033d7da0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 38f04b16c4edea00
RDX: 0000000000000000 RSI: ffffffff8a0b2460 RDI: ffffffff8a59a740
RBP: ffffc900033d7ec0 R08: dffffc0000000000 R09: fffffbfff1ff3619
R10: fffffbfff1ff3619 R11: 1ffffffff1ff3618 R12: ffffffff8c11bfa0
R13: 1ffff9200067afc0 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:312
 rcu_read_lock include/linux/rcupdate.h:739 [inline]
 __task_pid_nr_ns+0x21/0x420 kernel/pid.c:497
 task_tgid_vnr include/linux/sched.h:1585 [inline]
 __ia32_sys_getpid+0x19/0x20 kernel/sys.c:945
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fbbe8a578e7
Code: 0b e9 68 fe ff ff 48 83 c4 18 48 8d 3d b2 6f d6 00 5b 5d 41 5c 41 5d 41 5e 41 5f e9 13 f8 fb ff 0f 1f 00 b8 27 00 00 00 0f 05 <c3> 0f 1f 84 00 00 00 00 00 b8 6e 00 00 00 0f 05 c3 0f 1f 84 00 00
RSP: 002b:00007ffcee8e4348 EFLAGS: 00000206 ORIG_RAX: 0000000000000027
RAX: ffffffffffffffda RBX: 00007ffcee8e44b0 RCX: 00007fbbe8a578e7
RDX: 00007ffcee8e4380 RSI: 00007ffcee8e44b0 RDI: 0000000000000021
RBP: 0000000000000000 R08: 0025f2ff59f149e0 R09: 00000010ee8e4c1f
R10: 00007ffcee8e4a20 R11: 0000000000000206 R12: 00007fbbe8c87fac
R13: 00007ffcee8e4a20 R14: 0000000000012787 R15: 00007ffcee8e4a40
 </TASK>