syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
	(detected by 1, t=10502 jiffies, g=19653, q=346 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294973979-4294963477), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g19653 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:28096 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 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:
CPU: 1 PID: 6098 Comm: syz.5.421 Not tainted 6.1.147-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:should_resched arch/x86/include/asm/preempt.h:103 [inline]
RIP: 0010:__local_bh_enable_ip+0x132/0x1b0 kernel/softirq.c:428
Code: 8a e8 f2 d7 c7 08 65 66 8b 05 2a 40 b5 7e 66 85 c0 75 54 bf 01 00 00 00 e8 8b 4e 09 00 e8 d6 c2 38 00 fb 65 8b 05 56 0f b4 7e <85> c0 75 05 e8 a5 20 b2 ff 48 c7 04 24 0e 36 e0 45 4b c7 04 37 00
RSP: 0018:ffffc90003be7c20 EFLAGS: 00000282
RAX: 0000000080000000 RBX: 0000000000000200 RCX: dd1fc5f732e91100
RDX: dffffc0000000000 RSI: ffffffff8a8c0460 RDI: ffffffff8adef320
RBP: ffffc90003be7cb0 R08: dffffc0000000000 R09: ffffed1002ee5981
R10: ffffed1002ee5981 R11: 1ffff11002ee5980 R12: ffffffff812f0456
R13: 1ffff9200077cfff R14: dffffc0000000000 R15: 1ffff9200077cf84
FS:  00007fe073d366c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c309552 CR3: 000000003044a000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 handle_signal arch/x86/kernel/signal.c:844 [inline]
 arch_do_signal_or_restart+0xe9e/0x1230 arch/x86/kernel/signal.c:873
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xb1/0x140 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:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe072e4d980
Code: 44 24 20 0f 29 44 24 30 0f 29 44 24 40 48 8b 44 24 08 ff d0 48 83 c4 50 31 c0 5b 5d 41 5c 41 5d 41 5e c3 0f 1f 80 00 00 00 00 <c3> 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 c3 66 66 2e 0f 1f
RSP: 002b:00007fe073d35b38 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 00007fe0731b5fa8 RCX: 00007fe072f8e9a9
RDX: 00007fe073d35b40 RSI: 00007fe073d35c70 RDI: 0000000000000011
RBP: 00007fe0731b5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe0731b5fac
R13: 0000000000000000 R14: 00007ffeed89b6b0 R15: 00007ffeed89b798
 </TASK>