syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
	(detected by 0, t=10502 jiffies, g=3593, q=1)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294966882-4294956380), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g3593 f0x2 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:27000 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5026 [inline]
 __schedule+0x12c4/0x4590 kernel/sched/core.c:6372
 schedule+0x11b/0x1f0 kernel/sched/core.c:6455
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1884
 rcu_gp_fqs_loop+0x2af/0xf70 kernel/rcu/tree.c:1959
 rcu_gp_kthread+0xa4/0x360 kernel/rcu/tree.c:2132
 kthread+0x3f6/0x4f0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 0
CPU: 0 PID: 3524 Comm: syz-executor404 Not tainted 5.15.126-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb 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:481
 print_other_cpu_stall+0x137a/0x14d0 kernel/rcu/tree_stall.h:586
 check_cpu_stall kernel/rcu/tree_stall.h:729 [inline]
 rcu_pending kernel/rcu/tree.c:3911 [inline]
 rcu_sched_clock_irq+0x94f/0x1770 kernel/rcu/tree.c:2606
 update_process_times+0x196/0x200 kernel/time/timer.c:1788
 tick_sched_handle kernel/time/tick-sched.c:237 [inline]
 tick_sched_timer+0x22d/0x3c0 kernel/time/tick-sched.c:1441
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x55b/0xcf0 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x392/0x980 kernel/time/hrtimer.c:1811
 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_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xd4/0x130 kernel/locking/spinlock.c:194
Code: 9c 8f 44 24 20 42 80 3c 23 00 74 08 4c 89 f7 e8 b2 d2 a3 f7 f6 44 24 21 02 75 4e 41 f7 c7 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> d7 79 31 f7 65 8b 05 e8 b5 dc 75 85 c0 74 3f 48 c7 04 24 0e 36
RSP: 0018:ffffc90002d8f5a0 EFLAGS: 00000206
RAX: af23654a0a2c3000 RBX: 1ffff920005b1eb8 RCX: ffffffff8162eaf8
RDX: dffffc0000000000 RSI: ffffffff8a8b0c60 RDI: 0000000000000001
RBP: ffffc90002d8f630 R08: dffffc0000000000 R09: fffffbfff1f7ae36
R10: 0000000000000000 R11: dffffc0000000001 R12: dffffc0000000000
R13: 1ffff920005b1eb4 R14: ffffc90002d8f5c0 R15: 0000000000000246
 spin_unlock_irqrestore include/linux/spinlock.h:418 [inline]
 __wake_up_common_lock kernel/sched/wait.c:140 [inline]
 __wake_up_sync_key+0x121/0x1c0 kernel/sched/wait.c:205
 __unix_dgram_recvmsg+0x5fe/0x1260 net/unix/af_unix.c:2344
 ____sys_recvmsg+0x286/0x530
 ___sys_recvmsg+0x1ec/0x690 net/socket.c:2673
 do_recvmmsg+0x36f/0x8f0 net/socket.c:2767
 __sys_recvmmsg net/socket.c:2846 [inline]
 __do_sys_recvmmsg net/socket.c:2869 [inline]
 __se_sys_recvmmsg net/socket.c:2862 [inline]
 __x64_sys_recvmmsg+0x195/0x240 net/socket.c:2862
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f3bbaec95d9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 18 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3bbae69228 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 0000000000000039 RCX: 00007f3bbaec95d9
RDX: 00000000040002db RSI: 0000000020000740 RDI: 0000000000000003
RBP: 00007f3bbaf53338 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 00007f3bbaf53330
R13: 00007f3bbaf20074 R14: 00007ffeff248d20 R15: 00007ffeff248e08
 </TASK>