watchdog: BUG: soft lockup - CPU#1 stuck for 122s! [syz.9.2101:8236] Modules linked in: CPU: 1 PID: 8236 Comm: syz.9.2101 Tainted: G W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 RIP: 0010:qdisc_tree_reduce_backlog+0x136/0x340 net/sched/sch_api.c:798 Code: e8 0f da ff ff 48 85 c0 0f 84 03 02 00 00 49 89 c5 31 ff 8b 75 d0 e8 29 a9 b8 fd 4d 8d 75 18 4c 89 f0 48 c1 e8 03 80 3c 18 00 <74> 08 4c 89 f7 e8 20 95 f2 fd 4d 8b 36 49 83 c6 08 4c 89 f0 48 c1 RSP: 0018:ffffc90001526f28 EFLAGS: 00000246 RAX: 1ffff110233b7f03 RBX: dffffc0000000000 RCX: 0000000000000002 RDX: ffff88811bb18000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90001526f70 R08: ffff88811bb18000 R09: 0000000000000002 R10: 00000000ffffffff R11: 0000000000000002 R12: 00000000fffffff1 R13: ffff888119dbf800 R14: ffff888119dbf818 R15: ffff888119dbf840 FS: 00007f8cb1c906c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c26af97 CR3: 000000010d37f000 CR4: 00000000003526a0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: fq_change+0xb9e/0x10a0 net/sched/sch_fq.c:915 fq_init+0x3e3/0x5d0 net/sched/sch_fq.c:963 qdisc_create+0x780/0x1040 net/sched/sch_api.c:1265 tc_modify_qdisc+0x8da/0x14c0 net/sched/sch_api.c:1725 rtnetlink_rcv_msg+0x9db/0xb90 net/core/rtnetlink.c:5610 netlink_rcv_skb+0x1e0/0x430 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+0x88d/0xb30 net/netlink/af_netlink.c:1914 sock_sendmsg_nosec net/socket.c:652 [inline] __sock_sendmsg net/socket.c:664 [inline] ____sys_sendmsg+0x5a2/0x8c0 net/socket.c:2376 ___sys_sendmsg+0x1f0/0x260 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+0x1e2/0x2a0 net/socket.c:2466 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7f8cb3227ec9 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:00007f8cb1c90038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f8cb347efa0 RCX: 00007f8cb3227ec9 RDX: 0000000020040000 RSI: 0000200000001200 RDI: 000000000000000c RBP: 00007f8cb32aaf91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f8cb347f038 R14: 00007f8cb347efa0 R15: 00007fff0af4c588 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