syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 0, t=10502 jiffies, g=10149, q=54 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10501 (4294963144-4294952643), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g10149 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:27688 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_timeout+0x160/0x280 kernel/time/timer.c:2168
 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: 0 PID: 5818 Comm: syz-executor123 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:should_resched arch/x86/include/asm/preempt.h:104 [inline]
RIP: 0010:__local_bh_enable_ip+0x136/0x1c0 kernel/softirq.c:413
Code: 8a e8 3e 8a 16 09 65 66 8b 05 86 22 b2 7e 66 85 c0 75 54 bf 01 00 00 00 e8 07 ed 09 00 e8 b2 7a 3a 00 fb 65 8b 05 52 22 b2 7e <85> c0 75 05 e8 31 08 af ff 48 c7 04 24 0e 36 e0 45 4b c7 04 37 00
RSP: 0018:ffffc90004a7f840 EFLAGS: 00000286
RAX: 0000000080000000 RBX: 0000000000000200 RCX: 8248ced9b1e81500
RDX: dffffc0000000000 RSI: ffffffff8aaabce0 RDI: ffffffff8afc73a0
RBP: ffffc90004a7f8d0 R08: ffffffff8e4a39ef R09: 1ffffffff1c9473d
R10: dffffc0000000000 R11: fffffbfff1c9473e R12: ffffffff81313b9b
R13: dffffc0000000000 R14: dffffc0000000000 R15: 1ffff9200094ff08
FS:  0000555565b003c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f781d36a9e0 CR3: 000000001de69000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 fpregs_unlock arch/x86/include/asm/fpu/api.h:80 [inline]
 copy_fpstate_to_sigframe+0x49d/0xbe0 arch/x86/kernel/fpu/signal.c:233
 get_sigframe+0x5ce/0x7c0 arch/x86/kernel/signal.c:142
 x64_setup_rt_frame+0x158/0xcd0 arch/x86/kernel/signal_64.c:175
 setup_rt_frame arch/x86/kernel/signal.c:223 [inline]
 handle_signal arch/x86/kernel/signal.c:267 [inline]
 arch_do_signal_or_restart+0x3fa/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:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f781d35088a
Code: 48 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c 24 0c e8 b3 7e 02 00 8b 7c 24 0c 89 c2 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 36 89 d7 89 44 24 0c e8 13 7f 02 00 8b 44 24
RSP: 002b:00007ffff7345c40 EFLAGS: 00000293
RAX: fffffffffffffff7 RBX: 000000000000000a RCX: 00007f781d35088a
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000009
RBP: 0000000000000000 R08: 00007f781d309990 R09: 00007f781d309990
R10: 0000000000000000 R11: 0000000000000293 R12: 00007f781d3a805c
R13: 00007f781d3a110f R14: 00007ffff7345c90 R15: 0000000000000000
 </TASK>