watchdog: BUG: soft lockup - CPU#1 stuck for 114s! [syz.8.516:2318] Modules linked in: CPU: 1 PID: 2318 Comm: syz.8.516 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:qdisc_tree_reduce_backlog+0x200/0x340 net/sched/sch_api.c:796 Code: 4c 89 e7 e8 92 66 ec fd 4c 89 ff 4c 89 f6 41 ff 14 24 eb 05 e8 71 e0 b1 fd 49 8d bd a8 00 00 00 48 89 f8 48 c1 e8 03 49 89 de <0f> b6 04 18 84 c0 0f 85 aa 00 00 00 8b 45 c8 41 29 87 a8 00 00 00 RSP: 0018:ffffc900013cef08 EFLAGS: 00000a02 RAX: 1ffff110222ceb15 RBX: dffffc0000000000 RCX: 0000000000080000 RDX: ffffc90005139000 RSI: 000000000007ffff RDI: ffff8881116758a8 RBP: ffffc900013cef50 R08: ffff888118938000 R09: 0000000000000002 R10: 00000000ffffffff R11: 0000000000000002 R12: 00000000fffffff1 R13: ffff888111675800 R14: dffffc0000000000 R15: ffff888111675800 FS: 00007f81498c36c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000012756b000 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:5613 netlink_rcv_skb+0x1f5/0x440 net/netlink/af_netlink.c:2503 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5631 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: 0033:0x7f814ae68e59 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:00007f81498c3028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f814b0e1fa0 RCX: 00007f814ae68e59 RDX: 0000000020000000 RSI: 0000200000001200 RDI: 000000000000000b RBP: 00007f814aefed6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f814b0e2038 R14: 00007f814b0e1fa0 R15: 00007ffe9afa1cb8 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:60 [inline] NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:103 [inline] NMI backtrace for cpu 0 skipped: idling at default_idle+0x12/0x20 arch/x86/kernel/process.c:717