syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
	(detected by 0, t=10502 jiffies, g=17209, q=149)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294962398-4294951896), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g17209 f0x2 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:27584 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 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: 5847 Comm: syz.2.344 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:hlock_class kernel/locking/lockdep.c:192 [inline]
RIP: 0010:__lock_acquire+0x12ad/0x7c60 kernel/locking/lockdep.c:5009
Code: 00 00 74 12 48 89 df e8 01 23 60 00 49 b8 00 00 00 00 00 fc ff df 48 83 3b 00 0f 84 10 4b 00 00 48 8b 44 24 58 42 0f b6 04 00 <84> c0 0f 85 16 5a 00 00 41 8b 07 89 c3 81 e3 ff 1f 00 00 c1 e8 03
RSP: 0018:ffffc90000dd08c0 EFLAGS: 00000086
RAX: 0000000000000000 RBX: ffffffff8f932500 RCX: ffffffff815c0fcf
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8ffaa0c0
RBP: ffffc90000dd0b10 R08: dffffc0000000000 R09: fffffbfff1ff5419
R10: fffffbfff1ff5419 R11: 1ffffffff1ff5418 R12: 000000009be2421a
R13: ffff8880270b1dc0 R14: 0000000050ef4013 R15: ffff8880270b28f8
FS:  00007f5c4e5806c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5c4e55ef98 CR3: 000000002577f000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 advance_sched+0x6ca/0x940 net/sched/sch_taprio.c:769
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x53d/0xc40 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
 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:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa5/0x100 kernel/locking/spinlock.c:194
Code: 74 05 e8 be 9a d2 f7 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> d6 22 a6 f7 65 8b 05 67 20 57 76 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc90003587b80 EFLAGS: 00000206
RAX: c11ff16916c30200 RBX: 0000000000000a02 RCX: c11ff16916c30200
RDX: dffffc0000000000 RSI: ffffffff8a0b1be0 RDI: 0000000000000001
RBP: ffffc90003587c10 R08: dffffc0000000000 R09: fffffbfff1ff5419
R10: fffffbfff1ff5419 R11: 1ffffffff1ff5418 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff8880b902a240 R15: 1ffff920006b0f70
 clock_was_set+0x642/0x840 kernel/time/hrtimer.c:955
 do_settimeofday64+0x575/0x720 kernel/time/timekeeping.c:1328
 __do_sys_clock_settime kernel/time/posix-timers.c:1125 [inline]
 __se_sys_clock_settime kernel/time/posix-timers.c:1113 [inline]
 __x64_sys_clock_settime+0x223/0x270 kernel/time/posix-timers.c:1113
 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: 0033:0x7f5c5033a749
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:00007f5c4e580038 EFLAGS: 00000246 ORIG_RAX: 00000000000000e3
RAX: ffffffffffffffda RBX: 00007f5c50591090 RCX: 00007f5c5033a749
RDX: 0000000000000000 RSI: 0000200000000240 RDI: 0000000000000000
RBP: 00007f5c503bef91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5c50591128 R14: 00007f5c50591090 R15: 00007fff06f5fbe8
 </TASK>