rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P9006/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=20965, q=638 ncpus=2)
task:syz.4.328       state:R  running task     stack:25160 pid:9006  tgid:9003  ppid:5868   task_flags:0x400140 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7288
 irqentry_exit+0x6f/0x90 kernel/entry/common.c:197
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:rcu_read_lock include/linux/rcupdate.h:842 [inline]
RIP: 0010:class_rcu_constructor include/linux/rcupdate.h:1155 [inline]
RIP: 0010:unwind_next_frame+0xd6/0x2390 arch/x86/kernel/unwind_orc.c:479
Code: 31 f6 31 d2 b9 02 00 00 00 45 31 c0 45 31 c9 41 57 e8 be 98 2a 00 48 83 c4 08 e8 25 0d 07 0a 85 c0 74 3a e8 6c 9b 33 00 84 c0 <75> 31 e8 13 0d 07 0a 85 c0 74 28 80 3d 48 91 1a 0e 00 75 1f c6 05
RSP: 0018:ffffc90003676a98 EFLAGS: 00000202
RAX: 0000000000000001 RBX: ffffffff81000130 RCX: 444630e7579c8a00
RDX: 0000000000000001 RSI: ffffffff8be337e0 RDI: ffffffff8be337a0
RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffffff8172c195
R10: dffffc0000000000 R11: ffffffff81ac3820 R12: 1ffff920006ced6d
R13: ffffc90003676ba0 R14: ffffc90003676b68 R15: ffffffff8172c195
 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 unpoison_slab_object mm/kasan/common.c:330 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:356
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4180 [inline]
 slab_alloc_node mm/slub.c:4229 [inline]
 kmem_cache_alloc_node_noprof+0x1bb/0x3c0 mm/slub.c:4281
 __alloc_skb+0x112/0x2d0 net/core/skbuff.c:659
 alloc_skb include/linux/skbuff.h:1336 [inline]
 alloc_skb_with_frags+0xca/0x890 net/core/skbuff.c:6665
 sock_alloc_send_pskb+0x857/0x990 net/core/sock.c:2980
 sock_alloc_send_skb include/net/sock.h:1847 [inline]
 __ip_append_data+0x2ce8/0x40c0 net/ipv4/ip_output.c:1125
 ip_make_skb+0x1de/0x3f0 net/ipv4/ip_output.c:1572
 udp_sendmsg+0x1925/0x2170 net/ipv4/udp.c:1479
 sock_sendmsg_nosec net/socket.c:714 [inline]
 __sock_sendmsg+0x19c/0x270 net/socket.c:729
 ____sys_sendmsg+0x52d/0x830 net/socket.c:2614
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668
 __sys_sendmmsg+0x227/0x430 net/socket.c:2757
 __do_sys_sendmmsg net/socket.c:2784 [inline]
 __se_sys_sendmmsg net/socket.c:2781 [inline]
 __x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2781
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f815878ebe9
RSP: 002b:00007f815968b038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f81589c5fa0 RCX: 00007f815878ebe9
RDX: 000000000800001d RSI: 0000200000007fc0 RDI: 0000000000000003
RBP: 00007f8158811e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f81589c6038 R14: 00007f81589c5fa0 R15: 00007fff01fe4388
 </TASK>
rcu: rcu_preempt kthread starved for 10487 jiffies! g20965 f0x0 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:26792 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82
Code: 3e 7d 96 f5 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d f3 66 0e 00 f3 0f 1e fa fb f4 <e9> 13 7d 96 f5 cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffffff8de07d80 EFLAGS: 000002c2
RAX: 71fcf28d28721b00 RBX: ffffffff819683c8 RCX: 71fcf28d28721b00
RDX: 0000000000000001 RSI: ffffffff8d9b81b0 RDI: ffffffff8be33800
RBP: ffffffff8de07eb8 R08: ffff8880b8632f9b R09: 1ffff110170c65f3
R10: dffffc0000000000 R11: ffffed10170c65f4 R12: ffffffff8fa38f30
R13: 0000000000000000 R14: 0000000000000000 R15: 1ffffffff1bd2a20
FS:  0000000000000000(0000) GS:ffff888125c18000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3f5655cb5a CR3: 0000000058e37000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:757
 default_idle_call+0x74/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:190 [inline]
 do_idle+0x1e8/0x510 kernel/sched/idle.c:330
 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:428
 rest_init+0x2de/0x300 init/main.c:744
 start_kernel+0x3a9/0x410 init/main.c:1097
 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:307
 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:288
 common_startup_64+0x13e/0x147
 </TASK>