syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P9241/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=187237, q=140 ncpus=2)
task:syz.0.7483      state:R  running task     stack:26440 pid:9241  tgid:9233  ppid:25501  task_flags:0x400040 flags:0x00080003
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6929
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7256
 irqentry_exit+0x36/0x90 kernel/entry/common.c:211
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:preempt_count_add+0x0/0x150 kernel/sched/core.c:5784
Code: 1c 18 12 75 0f 48 83 ec 80 5b 5d 41 5c 41 5d c3 cc cc cc cc e8 71 2c d7 09 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 48 c7 c0 00 21 b1 9a 55 48 ba 00 00 00 00 00 fc ff df
RSP: 0018:ffffc90003277658 EFLAGS: 00000246
RAX: 0000000000080000 RBX: ffff8880570c62a0 RCX: ffffc9000f873000
RDX: 0000000000080000 RSI: ffffffff820c728e RDI: 0000000000000001
RBP: ffffc900032777a8 R08: 0000000000000007 R09: 0000000000000100
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000001
R13: 0000000000000001 R14: ffff88804c274280 R15: 0000000000000000
 __raw_spin_lock include/linux/spinlock_api_smp.h:132 [inline]
 _raw_spin_lock+0x12/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:351 [inline]
 handle_pte_fault mm/memory.c:6203 [inline]
 __handle_mm_fault+0x129b/0x2aa0 mm/memory.c:6336
 handle_mm_fault+0x589/0xd10 mm/memory.c:6505
 do_user_addr_fault+0x7a6/0x1370 arch/x86/mm/fault.c:1387
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x64/0xc0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0010:__put_user_nocheck_4+0x3/0x10 arch/x86/lib/putuser.S:104
Code: d9 0f 01 cb 89 01 31 c9 0f 01 ca e9 97 80 03 00 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 01 cb <89> 01 31 c9 0f 01 ca c3 cc cc cc cc 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc900032779e8 EFLAGS: 00050246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00002000002ce030
RDX: 0000000000080000 RSI: ffffffff89278903 RDI: 0000000000000005
RBP: ffffc90003277d88 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000000 R12: 0000000000000000
R13: 00002000002ce000 R14: ffffc90003277dcc R15: 0000000000000002
 ____sys_recvmsg+0x2ee/0x6b0 net/socket.c:2863
 ___sys_recvmsg+0x114/0x1a0 net/socket.c:2892
 do_recvmmsg+0x2fe/0x750 net/socket.c:2987
 __sys_recvmmsg net/socket.c:3061 [inline]
 __do_sys_recvmmsg net/socket.c:3084 [inline]
 __se_sys_recvmmsg net/socket.c:3077 [inline]
 __x64_sys_recvmmsg+0x22a/0x280 net/socket.c:3077
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0669d8f749
RSP: 002b:00007f066abac038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f0669fe6090 RCX: 00007f0669d8f749
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000003
RBP: 00007f0669e13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0669fe6128 R14: 00007f0669fe6090 R15: 00007ffdd7c4d858
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g187237 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=186858
rcu: rcu_preempt kthread starved for 10502 jiffies! g187237 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:28080 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7026
 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
 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+0x675/0x7d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </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: 9261 Comm: syz.4.7486 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:arch_atomic_try_cmpxchg arch/x86/include/asm/atomic.h:107 [inline]
RIP: 0010:raw_atomic_try_cmpxchg_acquire include/linux/atomic/atomic-arch-fallback.h:2170 [inline]
RIP: 0010:atomic_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:1302 [inline]
RIP: 0010:queued_spin_lock include/asm-generic/qspinlock.h:111 [inline]
RIP: 0010:do_raw_spin_lock+0x13d/0x2b0 kernel/locking/spinlock_debug.c:116
Code: 28 00 00 00 00 e8 e3 7e 8c 00 be 04 00 00 00 48 8d 7c 24 28 e8 d4 7e 8c 00 8b 44 24 28 ba 01 00 00 00 89 44 24 04 f0 0f b1 13 <0f> 85 94 00 00 00 65 44 8b 35 99 9c 08 12 48 b8 00 00 00 00 00 fc
RSP: 0000:ffffc90003517b98 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffffffff9ad53678 RCX: ffffffff8199137c
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffc90003517bc0
RBP: 1ffff920006a2f74 R08: 0000000000000001 R09: fffff520006a2f78
R10: 0000000000000003 R11: 0000000000000001 R12: ffffffff9ad53680
R13: ffffffff9ad53688 R14: ffffffff9ad53670 R15: 1ffff920006a2f8e
FS:  0000555571d5a500(0000) GS:ffff888124b05000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2e712ff8 CR3: 0000000057220000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
 _raw_spin_lock_irqsave+0x42/0x60 kernel/locking/spinlock.c:162
 debug_object_activate+0x14c/0x4c0 lib/debugobjects.c:818
 debug_hrtimer_activate kernel/time/hrtimer.c:438 [inline]
 debug_activate kernel/time/hrtimer.c:477 [inline]
 enqueue_hrtimer+0x23/0x3b0 kernel/time/hrtimer.c:1081
 __run_hrtimer kernel/time/hrtimer.c:1794 [inline]
 __hrtimer_run_queues+0x8ff/0xad0 kernel/time/hrtimer.c:1841
 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1903
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1041 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x3f0 arch/x86/kernel/apic/apic.c:1058
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
 sysvec_apic_timer_interrupt+0x52/0xc0 arch/x86/kernel/apic/apic.c:1052
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0033:0x7f87f0868326
Code: 77 f8 48 89 f8 48 89 eb eb 12 66 2e 0f 1f 84 00 00 00 00 00 48 8b 4b 08 48 83 c3 08 48 39 d1 72 f3 48 83 e8 08 48 39 f2 73 17 <66> 2e 0f 1f 84 00 00 00 00 00 48 8b 70 f8 48 83 e8 08 48 39 f2 72
RSP: 002b:00007ffd5caaaf00 EFLAGS: 00000283
RAX: 00007f87f03ff480 RBX: 00007f87f03ff3a0 RCX: ffffffff84580b94
RDX: ffffffff84578547 RSI: ffffffff845789b0 RDI: 00007f87f03ff500
RBP: 00007f87f03ff370 R08: 00007f87f03ff430 R09: 00007f87f0bd2000
R10: 00007f87f03ff008 R11: 000000000000000e R12: 00007f87f03ff368
R13: 000000000000000b R14: 00000000002b97e1 R15: 00007f87f03ff008
 </TASK>