syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 0, t=10502 jiffies, g=13485, q=660 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10496 (4294968502-4294958006), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10497 jiffies! g13485 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:29112 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x1139/0x6150 kernel/sched/core.c:6863
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7190
 irqentry_exit+0x1d8/0x8c0 kernel/entry/common.c:216
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:timer_destroy_on_stack+0x4/0x20 kernel/time/timer.c:822
Code: 41 5c 41 5d 41 5e e9 db f0 d0 09 e8 d6 bd cd 09 66 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa <53> 48 89 fb e8 13 b1 14 00 48 89 df 48 c7 c6 00 6c 90 8b 5b e9 d3
RSP: 0018:ffffc90000157b30 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 00000000ffffdbb7 RCX: ffffffff81aa42df
RDX: ffff88801daa8000 RSI: ffffffff81aa42e8 RDI: ffffc90000157b58
RBP: 1ffff9200002af67 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: ffff88801daa8b30 R12: ffffc90000157b58
R13: dffffc0000000000 R14: 1ffffffff1c02250 R15: 0000000000000001
 schedule_timeout+0x133/0x290 kernel/time/sleep_timeout.c:103
 rcu_gp_fqs_loop+0x1ea/0xaf0 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x26d/0x380 kernel/rcu/tree.c:2285
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6500 Comm: syz.6.105 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline]
RIP: 0010:write_comp_data+0x11/0x90 kernel/kcov.c:246
Code: bc 09 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 49 89 d2 49 89 f8 49 89 f1 65 48 8b 15 27 c3 f3 11 <65> 8b 05 38 c3 f3 11 a9 00 01 ff 00 74 1d f6 c4 01 74 67 a9 00 00
RSP: 0018:ffffc900035c7ee0 EFLAGS: 00000246
RAX: 0000000000000001 RBX: 0000000000000001 RCX: ffffffff8185d372
RDX: ffff888033fb24c0 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: ffff888033fb2ff0 R12: ffff888033fb24c0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007fbb4bf0e6c0(0000) GS:ffff8881249f6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000058 CR3: 0000000075d6f000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 rcu_read_lock include/linux/rcupdate.h:868 [inline]
 __task_pid_nr_ns+0x232/0x500 kernel/pid.c:515
 task_tgid_vnr include/linux/pid.h:298 [inline]
 __do_sys_getpid+0x1d/0x30 kernel/sys.c:1001
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbb4af865e7
Code: 0b e9 68 fe ff ff 48 83 c4 18 48 8d 3d b2 62 d9 00 5b 5d 41 5c 41 5d 41 5e 41 5f e9 23 f8 fb ff 0f 1f 00 b8 27 00 00 00 0f 05 <c3> 0f 1f 84 00 00 00 00 00 b8 6e 00 00 00 0f 05 c3 0f 1f 84 00 00
RSP: 002b:00007fbb4bf0d3c8 EFLAGS: 00000202 ORIG_RAX: 0000000000000027
RAX: ffffffffffffffda RBX: 00007fbb4bf0d530 RCX: 00007fbb4af865e7
RDX: 00007fbb4bf0d400 RSI: 00007fbb4bf0d530 RDI: 0000000000000021
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 00007fbb4b1e6038 R14: 00007ffd4618b4e0 R15: 00007ffd4618b5c8
 </TASK>