syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
	(detected by 1, t=10502 jiffies, g=8353, q=113 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294955653-4294945150), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10504 jiffies! g8353 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:26416 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x303/0x1340 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x99/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4290 Comm: syz-executor788 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:signal_delivered kernel/signal.c:2906 [inline]
RIP: 0010:signal_setup_done+0x20b/0x490 kernel/signal.c:2919
Code: 4c 89 e7 e8 d7 6a 81 00 4d 8b 24 24 4c 89 e6 48 81 e6 00 00 00 40 31 ff e8 f2 66 30 00 49 81 e4 00 00 00 40 0f 85 b0 00 00 00 <49> 83 c7 50 4c 89 f8 48 c1 e8 03 49 bc 00 00 00 00 00 fc ff df 42
RSP: 0018:ffffc90003c97b40 EFLAGS: 00000246
RAX: ffffffff8152188e RBX: dffffc0000000000 RCX: ffff8880184cda00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003c97c90 R08: ffff8880184cda07 R09: 1ffff11003099b40
R10: dffffc0000000000 R11: ffffed1003099b41 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffffc90003c97de0
FS:  00007ff93c8396c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000058 CR3: 0000000029520000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 handle_signal arch/x86/kernel/signal.c:846 [inline]
 arch_do_signal_or_restart+0xf83/0x1350 arch/x86/kernel/signal.c:873
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff93c86d190
Code: 83 c0 16 83 e0 f7 74 12 50 48 8d 3d 2a a4 06 00 e8 85 ae fd ff 0f 1f 44 00 00 c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 <83> ff 21 74 0b c3 66 2e 0f 1f 84 00 00 00 00 00 55 53 48 89 f3 48
RSP: 002b:00007ff93c838bb8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 00007ff93c909b28 RCX: 00007ff93c85a519
RDX: 00007ff93c838bc0 RSI: 00007ff93c838cf0 RDI: 0000000000000021
RBP: 00007ff93c909b20 R08: 00007ff93c839cdc R09: 00007ff93c839cdc
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff93c909b2c
R13: 0000000000000000 R14: 00007ffc3894c490 R15: 00007ffc3894c578
 </TASK>