watchdog: BUG: soft lockup - CPU#1 stuck for 123s! [syz.3.1056:4195] Modules linked in: CPU: 1 PID: 4195 Comm: syz.3.1056 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:qdisc_dev include/net/sch_generic.h:603 [inline] RIP: 0010:qdisc_tree_reduce_backlog+0xcb/0x340 net/sched/sch_api.c:783 Code: 85 70 02 00 00 49 8d bf a8 00 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 db 01 00 00 41 8b 87 a8 00 00 00 89 45 d0 <49> 83 c7 40 4c 89 f8 48 c1 e8 03 4c 89 f3 42 80 3c 30 00 74 08 4c RSP: 0018:ffffc90001056f08 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000002 RDX: ffff88811f124f00 RSI: 0000000000000000 RDI: ffff888126a120a8 RBP: ffffc90001056f50 R08: ffff88811f124f00 R09: 0000000000000002 R10: 00000000ffffffff R11: 0000000000000002 R12: 00000000fffffff1 R13: ffff888126a120cc R14: dffffc0000000000 R15: ffff888126a12000 FS: 00007f4aced146c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f4aced13ff8 CR3: 000000011ac57000 CR4: 00000000003506a0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: fq_codel_change+0xa6e/0xeb0 net/sched/sch_fq_codel.c:436 fq_codel_init+0x342/0xa20 net/sched/sch_fq_codel.c:473 qdisc_create+0x848/0x1220 net/sched/sch_api.c:1255 tc_modify_qdisc+0x8a1/0x1490 net/sched/sch_api.c:-1 rtnetlink_rcv_msg+0xa31/0xcc0 net/core/rtnetlink.c:5610 netlink_rcv_skb+0x1f5/0x440 net/netlink/af_netlink.c:2503 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5628 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline] netlink_unicast+0x876/0xa40 net/netlink/af_netlink.c:1340 netlink_sendmsg+0x89c/0xb50 net/netlink/af_netlink.c:1914 sock_sendmsg_nosec net/socket.c:652 [inline] __sock_sendmsg net/socket.c:664 [inline] ____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2376 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2430 __sys_sendmsg net/socket.c:2459 [inline] __do_sys_sendmsg net/socket.c:2468 [inline] __se_sys_sendmsg net/socket.c:2466 [inline] __x64_sys_sendmsg+0x1f9/0x2c0 net/socket.c:2466 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7f4ad02da629 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f4aced14028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f4ad0554090 RCX: 00007f4ad02da629 RDX: 0000000000008840 RSI: 0000200000000740 RDI: 0000000000000009 RBP: 00007f4ad0370b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f4ad0554128 R14: 00007f4ad0554090 R15: 00007ffcd19902e8 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 9 Comm: kworker/u4:1 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Workqueue: events_unbound toggle_allocation_gate RIP: 0010:csd_lock_wait kernel/smp.c:229 [inline] RIP: 0010:smp_call_function_single+0x209/0x490 kernel/smp.c:517 Code: 48 44 89 f6 83 e6 01 31 ff e8 13 88 0a 00 41 83 e6 01 49 bc 00 00 00 00 00 fc ff df 75 0a e8 4e 84 0a 00 e9 a4 00 00 00 f3 90 44 24 48 01 00 00 00 0f 84 8f 00 00 00 e8 34 84 0a 00 eb e9 e8 RSP: 0018:ffffc90000097720 EFLAGS: 00000293 RAX: ffffffff815a321c RBX: 0000000000000000 RCX: ffff88810024bb40 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90000097810 R08: ffff8881f7157647 R09: 1ffff1103ee2aec8 R10: dffffc0000000000 R11: ffffed103ee2aec9 R12: dffffc0000000000 R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff92000012ee8 FS: 0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa22b0b5000 CR3: 000000000640f000 CR4: 00000000003506b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: smp_call_function_many_cond+0x90a/0xa00 kernel/smp.c:653 smp_call_function_many kernel/smp.c:716 [inline] smp_call_function kernel/smp.c:738 [inline] on_each_cpu+0xab/0x180 kernel/smp.c:837 text_poke_sync arch/x86/kernel/alternative.c:1568 [inline] text_poke_bp_batch+0x1cb/0x5f0 arch/x86/kernel/alternative.c:1768 text_poke_flush arch/x86/kernel/alternative.c:1959 [inline] text_poke_finish+0x1a/0x30 arch/x86/kernel/alternative.c:1966 arch_jump_label_transform_apply+0x15/0x30 arch/x86/kernel/jump_label.c:126 __jump_label_update+0x37c/0x3a0 kernel/jump_label.c:459 jump_label_update+0x34c/0x3e0 kernel/jump_label.c:825 static_key_disable_cpuslocked+0xc5/0x1a0 kernel/jump_label.c:207 static_key_disable+0x1a/0x30 kernel/jump_label.c:215 toggle_allocation_gate+0x3a5/0x440 mm/kfence/core.c:638 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301 worker_thread+0xa6a/0x13c0 kernel/workqueue.c:2447 kthread+0x346/0x3d0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298