syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 1, t=10502 jiffies, g=6777, q=195 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294955393-4294944890), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10504 jiffies! g6777 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:27408 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_timeout+0x160/0x280 kernel/time/timer.c:2167
 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 PID: 5801 Comm: syz-executor371 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:202
Code: 00 f3 0f 1e fa 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 0a 04 ef f6 48 89 df e8 22 d6 ef f6 e8 3d 7c 13 f7 fb bf 01 00 00 00 <e8> 62 f8 e2 f6 65 8b 05 53 41 8b 75 85 c0 74 02 5b c3 e8 70 25 88
RSP: 0018:ffffc90004487d20 EFLAGS: 00000282
RAX: 9768ec850822d600 RBX: ffff88802d230000 RCX: 9768ec850822d600
RDX: dffffc0000000000 RSI: ffffffff8aaabce0 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffffffff8e4a8d6f R09: 1ffffffff1c951ad
R10: dffffc0000000000 R11: fffffbfff1c951ae R12: 0000000000000000
R13: 0000000100000000 R14: ffff88807b2cbc00 R15: 0000000000000020
FS:  00007fd2bbb566c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000058 CR3: 000000007ad10000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 set_current_blocked kernel/signal.c:3077 [inline]
 signal_delivered kernel/signal.c:2938 [inline]
 signal_setup_done+0x189/0x310 kernel/signal.c:2950
 handle_signal arch/x86/kernel/signal.c:285 [inline]
 arch_do_signal_or_restart+0x4a6/0x7b0 arch/x86/kernel/signal.c:312
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd2bbbbbd70
Code: 83 c0 16 83 e0 f7 74 12 50 48 8d 3d da 28 03 00 e8 35 12 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:00007fd2bbb55bb8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 00007fd2bbc20308 RCX: 00007fd2bbb960d9
RDX: 00007fd2bbb55bc0 RSI: 00007fd2bbb55cf0 RDI: 0000000000000021
RBP: 00007fd2bbc20300 R08: 00007fd2bbb566c0 R09: 00007fd2bbb566c0
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd2bbc2030c
R13: 0000000000000000 R14: 00007fff0d061a10 R15: 00007fff0d061af8
 </TASK>