syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (0 ticks this GP) idle=9f1c/1/0x4000000000000000 softirq=616390/616390 fqs=0
rcu: 	(detected by 0, t=10502 jiffies, g=377485, q=372 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 19395 Comm: syz.7.18771 Not tainted 6.17.0-rc1-syzkaller-00224-g8d561baae505 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:_raw_spin_lock_irqsave+0x42/0x60 kernel/locking/spinlock.c:162
Code: 00 e8 82 67 f2 f5 ff 74 24 10 48 8d 7b 18 45 31 c9 31 c9 41 b8 01 00 00 00 31 d2 31 f6 e8 56 a6 01 f6 48 89 df e8 3e ef 01 f6 <58> 48 89 e8 5b 5d c3 cc cc cc cc e8 8e 55 2d f6 eb c0 66 66 2e 0f
RSP: 0018:ffffc90000a08d00 EFLAGS: 00000092
RAX: 0000000000000000 RBX: ffffffff9b045430 RCX: ffffffff8198119c
RDX: 1ffffffff3608a88 RSI: 0000000000000004 RDI: ffffc90000a08c90
RBP: 0000000000000006 R08: 0000000000000001 R09: fffff52000141192
R10: 0000000000000003 R11: ffffffff9b045430 R12: dffffc0000000000
R13: ffff88806af1e340 R14: ffffffff9b045428 R15: 1ffff920001411a8
FS:  00007f1a5517f6c0(0000) GS:ffff8881247bc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000040 CR3: 000000003953c000 CR4: 00000000003526f0
DR0: 0000000000000680 DR1: 0000000000000003 DR2: 0000000000000007
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 debug_object_activate+0x14c/0x4c0 lib/debugobjects.c:818
 debug_hrtimer_activate kernel/time/hrtimer.c:445 [inline]
 debug_activate kernel/time/hrtimer.c:484 [inline]
 enqueue_hrtimer+0x23/0x3b0 kernel/time/hrtimer.c:1088
 __run_hrtimer kernel/time/hrtimer.c:1778 [inline]
 __hrtimer_run_queues+0x8ff/0xad0 kernel/time/hrtimer.c:1825
 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1887
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x3f0 arch/x86/kernel/apic/apic.c:1056
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1050
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:finish_task_switch.isra.0+0x22a/0xc10 kernel/sched/core.c:5225
Code: fb 09 00 00 44 8b 05 69 62 22 0f 45 85 c0 0f 85 be 01 00 00 4c 89 e7 e8 a4 f6 ff ff e8 7f 6d 3a 00 fb 65 48 8b 1d fe 34 4d 12 <48> 8d bb 18 16 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1
RSP: 0018:ffffc9000b1c74b8 EFLAGS: 00000246
RAX: 0000000000000001 RBX: ffff888032012440 RCX: ffffffff81c3778f
RDX: 0000000000000000 RSI: ffffffff8c162680 RDI: ffffffff81890b11
RBP: ffffc9000b1c7500 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff90ab3b97 R11: 0000000000000001 R12: ffff8880b853a300
R13: ffff888053fd4880 R14: ffff8880b843a300 R15: ffff8880b853b170
 context_switch kernel/sched/core.c:5360 [inline]
 __schedule+0x1198/0x5de0 kernel/sched/core.c:6961
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7288
 irqentry_exit+0x36/0x90 kernel/entry/common.c:197
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:check_kcov_mode kernel/kcov.c:185 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x3b/0x70 kernel/kcov.c:217
Code: 8b 05 39 ae 1a 12 a9 00 01 ff 00 74 1d f6 c4 01 74 43 a9 00 00 0f 00 75 3c a9 00 00 f0 00 75 35 8b 82 3c 16 00 00 85 c0 74 2b <8b> 82 18 16 00 00 83 f8 02 75 20 48 8b 8a 20 16 00 00 8b 92 1c 16
RSP: 0018:ffffc9000b1c77a0 EFLAGS: 00000246
RAX: 0000000080000000 RBX: 0000000000000000 RCX: ffffffff8969fb73
RDX: ffff888032012440 RSI: ffffffff8969fb80 RDI: 0000000000000001
RBP: ffff888067af5780 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffffc9000b1c7da8 R14: 0000000000000000 R15: 0000000000000000
 skb_end_pointer include/linux/skbuff.h:1677 [inline]
 __skb_datagram_iter+0x240/0x900 net/core/datagram.c:415
 skb_copy_datagram_iter+0x40/0x50 net/core/datagram.c:535
 skb_copy_datagram_msg include/linux/skbuff.h:4167 [inline]
 __unix_dgram_recvmsg+0x446/0xc30 net/unix/af_unix.c:2643
 unix_dgram_recvmsg+0xd0/0x110 net/unix/af_unix.c:2700
 sock_recvmsg_nosec net/socket.c:1065 [inline]
 ____sys_recvmsg+0x5f6/0x6b0 net/socket.c:2832
 ___sys_recvmsg+0x114/0x1a0 net/socket.c:2876
 do_recvmmsg+0x2fe/0x750 net/socket.c:2971
 __sys_recvmmsg net/socket.c:3045 [inline]
 __do_sys_recvmmsg net/socket.c:3068 [inline]
 __se_sys_recvmmsg net/socket.c:3061 [inline]
 __x64_sys_recvmmsg+0x22a/0x280 net/socket.c:3061
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1a5438ebe9
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:00007f1a5517f038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f1a545b6090 RCX: 00007f1a5438ebe9
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000003
RBP: 00007f1a54411e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1a545b6128 R14: 00007f1a545b6090 R15: 00007ffed5367048
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g377485 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=232874
rcu: rcu_preempt kthread starved for 10502 jiffies! g377485 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:28224 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7058
 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2285
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>