rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 GPs behind) idle=2534/1/0x4000000000000000 softirq=51522/51530 fqs=0
rcu: 	(detected by 1, t=10505 jiffies, g=41409, q=60 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 11646 Comm: syz.4.1604 Not tainted 6.15.0-rc4-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
RIP: 0010:kasan_mem_to_shadow include/linux/kasan.h:64 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:130 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:161 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x4d/0x1a0 mm/kasan/generic.c:189
Code: ff ff ff ff ff 7f ff ff 48 39 f8 0f 83 b3 00 00 00 4c 8d 54 37 ff 48 89 fd 48 b8 00 00 00 00 00 fc ff df 4d 89 d1 48 c1 ed 03 <49> c1 e9 03 48 01 c5 49 01 c1 48 89 e8 49 8d 59 01 48 89 da 48 29
RSP: 0018:ffffc90000007e20 EFLAGS: 00000802
RAX: dffffc0000000000 RBX: ffff8880b8427940 RCX: ffffffff81a85e68
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff9084f010
RBP: 1ffffffff2109e02 R08: 0000000000000000 R09: ffffffff9084f017
R10: ffffffff9084f017 R11: 0000000000000000 R12: ffff8880b8427840
R13: 0000000000000000 R14: ffff88805c038340 R15: ffffffff8980f940
FS:  00007fa5fd7c46c0(0000) GS:ffff8881249e4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2de6b6 CR3: 0000000035d05000 CR4: 00000000003526f0
DR0: 0000040000000000 DR1: 000000000000064f DR2: 0000000000000006
DR3: 0000000000000006 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 cpumask_test_cpu include/linux/cpumask.h:587 [inline]
 cpu_online include/linux/cpumask.h:1143 [inline]
 trace_hrtimer_expire_entry include/trace/events/timer.h:259 [inline]
 __run_hrtimer kernel/time/hrtimer.c:1758 [inline]
 __hrtimer_run_queues+0x578/0xad0 kernel/time/hrtimer.c:1825
 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1887
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline]
 __sysvec_apic_timer_interrupt+0x108/0x3f0 arch/x86/kernel/apic/apic.c:1055
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1049
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:194
Code: f5 53 48 8b 74 24 10 48 89 fb 48 83 c7 18 e8 f6 2c 29 f6 48 89 df e8 9e 80 29 f6 f7 c5 00 02 00 00 75 23 9c 58 f6 c4 02 75 37 <bf> 01 00 00 00 e8 f5 ec 19 f6 65 8b 05 1e e4 34 08 85 c0 74 16 5b
RSP: 0018:ffffc900069cf818 EFLAGS: 00000246
RAX: 0000000000000002 RBX: ffff8880251b1780 RCX: 0000000000000006
RDX: 0000000000000000 RSI: ffffffff8dbdf889 RDI: ffffffff8bf47d60
RBP: 0000000000000282 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff9084f017 R11: 0000000000000000 R12: 0000000000000002
R13: ffff8880251b15f0 R14: ffff8880251b17c0 R15: ffff8880251b1168
 __unix_dgram_recvmsg+0x326/0xee0 net/unix/af_unix.c:2447
 unix_dgram_recvmsg+0xd0/0x110 net/unix/af_unix.c:2522
 sock_recvmsg_nosec net/socket.c:1017 [inline]
 ____sys_recvmsg+0x5f6/0x6b0 net/socket.c:2784
 ___sys_recvmsg+0x114/0x1a0 net/socket.c:2828
 do_recvmmsg+0x2fe/0x740 net/socket.c:2923
 __sys_recvmmsg net/socket.c:2997 [inline]
 __do_sys_recvmmsg net/socket.c:3020 [inline]
 __se_sys_recvmmsg net/socket.c:3013 [inline]
 __x64_sys_recvmmsg+0x22a/0x280 net/socket.c:3013
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa5fc98e969
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa5fd7c4038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007fa5fcbb6080 RCX: 00007fa5fc98e969
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000005
RBP: 00007fa5fca10ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007fa5fcbb6080 R15: 00007ffe39944ac8
 </TASK>
rcu: rcu_preempt kthread starved for 10505 jiffies! g41409 f0x0 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:28488 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x116f/0x5de0 kernel/sched/core.c:6767
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6860
 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2046
 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2248
 kthread+0x3c2/0x780 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 5810 Comm: kworker/1:3 Not tainted 6.15.0-rc4-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Workqueue: events fqdir_free_fn
RIP: 0010:csd_lock_wait kernel/smp.c:340 [inline]
RIP: 0010:smp_call_function_single+0x1c1/0x580 kernel/smp.c:679
Code: 40 66 44 89 6c 24 4e 48 89 de 66 89 44 24 4c e8 b5 fa ff ff 41 89 c5 0f 1f 44 00 00 e8 b8 f3 0b 00 eb 07 e8 b1 f3 0b 00 f3 90 <8b> 5c 24 48 31 ff 83 e3 01 89 de e8 df ee 0b 00 85 db 75 e5 e8 96
RSP: 0018:ffffc90004307ac0 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff81af3d61
RDX: ffff888061678000 RSI: ffffffff81af3d4f RDI: 0000000000000005
RBP: ffffc90004307ba0 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 1ffff92000860f5c
R13: 0000000000000000 R14: 0000000000000001 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff888124ae4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8461ae327a CR3: 000000002a650000 CR4: 00000000003526f0
DR0: 0000000000000007 DR1: 0000000000000002 DR2: 0000000000000008
DR3: 1000000100000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 rcu_barrier kernel/rcu/tree.c:3826 [inline]
 rcu_barrier+0x28d/0x6e0 kernel/rcu/tree.c:3763
 fqdir_free_fn+0x32/0x130 net/ipv4/inet_fragment.c:166
 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c2/0x780 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>