syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
	(detected by 1, t=10502 jiffies, g=7801, q=69 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294955418-4294944915), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10504 jiffies! g7801 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:27840 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: 4294 Comm: syz-executor354 Not tainted 6.1.147-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline]
RIP: 0010:__local_bh_disable_ip+0xd9/0x190 kernel/softirq.c:364
Code: 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 0f 85 9d 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 65 8b 05 df 11 b4 7e <25> ff ff ff 7f 39 d8 75 41 48 8b 5d 08 48 89 df e8 d2 bc 15 00 85
RSP: 0018:ffffc90003ce7bc0 EFLAGS: 00000206
RAX: 0000000080000200 RBX: 0000000000000200 RCX: ffffffff96be4103
RDX: 0000000000000000 RSI: 0000000000000200 RDI: ffffffff812f0456
RBP: ffffc90003ce7c78 R08: dffffc0000000000 R09: fffffbfff1c3e976
R10: fffffbfff1c3e976 R11: 1ffffffff1c3e975 R12: 1ffff9200079cf78
R13: 1ffff9200079cfff R14: 0000000000000246 R15: dffffc0000000000
FS:  00005555602663c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000006b000 CR3: 000000006f33b000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 local_bh_disable include/linux/bottom_half.h:20 [inline]
 fpregs_lock arch/x86/include/asm/fpu/api.h:72 [inline]
 fpu__clear_user_states+0x43/0x260 arch/x86/kernel/fpu/core.c:711
 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: 0033:0x7f90922b4e10
Code: 83 c0 16 83 e0 f7 74 12 50 48 8d 3d 9a 29 03 00 e8 d5 06 fb 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:00007ffef43ccaf8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007f909228e919
RDX: 00007ffef43ccb00 RSI: 00007ffef43ccc30 RDI: 0000000000000021
RBP: 0000000000000000 R08: 00007f909224e990 R09: 00007f909224e990
R10: 00007f909224e990 R11: 0000000000000246 R12: 00007f90922ec33c
R13: 00007f90922e6106 R14: 00007ffef43cd0c0 R15: 0000000000000000
 </TASK>