rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P9901/1:b..l rcu: (detected by 1, t=10506 jiffies, g=29493, q=1166 ncpus=2) task:syz.1.801 state:R running task stack:25032 pid:9901 tgid:9892 ppid:5820 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1139/0x6150 kernel/sched/core.c:6863 preempt_schedule_common+0x44/0xc0 kernel/sched/core.c:7047 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __slab_alloc.constprop.0+0xcb/0x110 mm/slub.c:4782 __slab_alloc_node mm/slub.c:4855 [inline] slab_alloc_node mm/slub.c:5251 [inline] __kmalloc_cache_noprof+0x485/0x800 mm/slub.c:5771 kmalloc_noprof include/linux/slab.h:957 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] ref_tracker_alloc+0x18e/0x5b0 lib/ref_tracker.c:271 __netdev_tracker_alloc include/linux/netdevice.h:4400 [inline] netdev_hold include/linux/netdevice.h:4429 [inline] dst_init+0xda/0x580 net/core/dst.c:52 dst_alloc+0xbb/0x1a0 net/core/dst.c:93 rt_dst_alloc+0x35/0x3a0 net/ipv4/route.c:1651 __mkroute_output net/ipv4/route.c:2655 [inline] ip_route_output_key_hash_rcu+0x87a/0x28e0 net/ipv4/route.c:2875 ip_route_output_key_hash+0x10f/0x2b0 net/ipv4/route.c:2705 __ip_route_output_key include/net/route.h:169 [inline] ip_route_output_flow+0x27/0x150 net/ipv4/route.c:2932 udp_sendmsg+0x1af9/0x2870 net/ipv4/udp.c:1450 inet_sendmsg+0x105/0x140 net/ipv4/af_inet.c:859 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0x973/0xc30 net/socket.c:2592 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2646 __sys_sendmmsg+0x200/0x420 net/socket.c:2735 __do_sys_sendmmsg net/socket.c:2762 [inline] __se_sys_sendmmsg net/socket.c:2759 [inline] __x64_sys_sendmmsg+0x9c/0x100 net/socket.c:2759 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: 0033:0x7f4d0818f749 RSP: 002b:00007f4d0907b038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007f4d083e6270 RCX: 00007f4d0818f749 RDX: 000000000800001d RSI: 0000200000007fc0 RDI: 0000000000000007 RBP: 00007f4d08213f91 R08: 0000000000000000 R09: 0000000000000000 R10: 000000000000001c R11: 0000000000000246 R12: 0000000000000000 R13: 00007f4d083e6308 R14: 00007f4d083e6270 R15: 00007ffd9d58edf8 rcu: rcu_preempt kthread timer wakeup didn't happen for 10491 jiffies! g29493 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=0 timer-softirq=30088 rcu: rcu_preempt kthread starved for 10492 jiffies! g29493 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:28584 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1139/0x6150 kernel/sched/core.c:6863 __schedule_loop kernel/sched/core.c:6945 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6960 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+0x983/0xb10 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 9921 Comm: modprobe Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:__lock_is_held kernel/locking/lockdep.c:5599 [inline] RIP: 0010:lock_is_held_type+0x99/0x150 kernel/locking/lockdep.c:5940 Code: 65 ff 05 d2 e0 3a 08 41 8b 84 24 28 0b 00 00 85 c0 7f 17 e9 92 00 00 00 41 83 c7 01 45 3b bc 24 28 0b 00 00 0f 8d 80 00 00 00 <49> 63 c7 48 89 ee 48 8d 04 80 49 8d 5c c5 00 48 89 df e8 90 fe ff RSP: 0018:ffffc90000007e00 EFLAGS: 00000097 RAX: 0000000000000000 RBX: ffff888035da8b58 RCX: 0000000000000001 RDX: 0000000000000000 RSI: ffff8880b8428458 RDI: ffff888035da8b58 RBP: ffff8880b8428458 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: ffffffff9aea33e8 R12: ffff888035da8000 R13: ffff888035da8b30 R14: 00000000ffffffff R15: 0000000000000002 FS: 0000000000000000(0000) GS:ffff8881248f5000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fef64d69440 CR3: 0000000031227000 CR4: 00000000003526f0 Call Trace: lock_is_held include/linux/lockdep.h:249 [inline] __run_hrtimer kernel/time/hrtimer.c:1743 [inline] __hrtimer_run_queues+0x960/0xc40 kernel/time/hrtimer.c:1841 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1903 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline] __sysvec_apic_timer_interrupt+0x10b/0x3c0 arch/x86/kernel/apic/apic.c:1062 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:stack_access_ok+0x16d/0x200 arch/x86/kernel/unwind_orc.c:414 Code: 8b 43 10 49 39 ee 77 29 48 39 e8 76 24 4c 01 e5 48 39 e8 0f 93 c0 49 39 ee 0f 92 c2 21 d0 48 83 c4 08 5b 5d 41 5c 41 5d 41 5e <41> 5f e9 8c 8e 0e 0a 48 83 c4 08 31 c0 5b 5d 41 5c 41 5d 41 5e 41 RSP: 0018:ffffc9000c68f2c0 EFLAGS: 00000282 RAX: 0000000000000001 RBX: 0000000000000001 RCX: ffffc9000c690000 RDX: ffffc9000c68f301 RSI: ffffc9000c68f388 RDI: ffffc9000c68f390 RBP: ffffc9000c68f3d8 R08: ffffffff9120f58c R09: 0000000092b4c5e2 R10: 0000000000000002 R11: 0000000000006cdb R12: ffffc9000c68f3e0 R13: ffffc9000c68f390 R14: ffffc9000c68f390 R15: ffffc9000c688000 deref_stack_reg arch/x86/kernel/unwind_orc.c:419 [inline] unwind_next_frame+0xb7d/0x20b0 arch/x86/kernel/unwind_orc.c:600 __unwind_start+0x45f/0x7f0 arch/x86/kernel/unwind_orc.c:773 unwind_start arch/x86/include/asm/unwind.h:64 [inline] arch_stack_walk+0x73/0x100 arch/x86/kernel/stacktrace.c:24 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x33/0x60 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2540 [inline] slab_free mm/slub.c:6670 [inline] kfree+0x2f8/0x6e0 mm/slub.c:6878 tomoyo_check_open_permission+0x19f/0x3c0 security/tomoyo/file.c:786 tomoyo_file_open+0x6b/0x90 security/tomoyo/tomoyo.c:334 security_file_open+0x84/0x1e0 security/security.c:2636 do_dentry_open+0x597/0x1590 fs/open.c:939 vfs_open+0x82/0x3f0 fs/open.c:1094 do_open fs/namei.c:4628 [inline] path_openat+0x2078/0x3140 fs/namei.c:4787 do_filp_open+0x20b/0x470 fs/namei.c:4814 do_sys_openat2+0x121/0x290 fs/open.c:1430 do_sys_open fs/open.c:1436 [inline] __do_sys_openat fs/open.c:1452 [inline] __se_sys_openat fs/open.c:1447 [inline] __x64_sys_openat+0x174/0x210 fs/open.c:1447 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: 0033:0x7fef6504b0ba Code: 41 89 f2 48 89 54 24 e0 41 83 e2 40 75 2a 89 f0 f7 d0 a9 00 00 41 00 74 1f 89 f2 b8 01 01 00 00 48 89 fe bf 9c ff ff ff 0f 05 <48> 3d 00 f0 ff ff 77 2e c3 0f 1f 44 00 00 48 8d 44 24 08 c7 44 24 RSP: 002b:00007ffc08bcbc78 EFLAGS: 00000206 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007ffc08bcbcf0 RCX: 00007fef6504b0ba RDX: 0000000000080000 RSI: 00007ffc08bcbcf0 RDI: 00000000ffffff9c RBP: 00007ffc08bcbce0 R08: 00007ffc08bcbee7 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000016 R13: 00007fef6501f000 R14: 00007ffc08bcbf00 R15: 0000000000000000