watchdog: BUG: soft lockup - CPU#1 stuck for 246s! [syz.1.2856:10084]
Modules linked in:
CPU: 1 PID: 10084 Comm: syz.1.2856 Tainted: G        W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:qdisc_tree_reduce_backlog+0x45/0x340 net/sched/sch_api.c:775
Code: 00 00 00 00 00 fc ff df e8 58 2d 8f fd 31 c0 85 db 89 5d c8 0f 4f c3 89 45 cc e8 b6 09 7d fd 49 8d 5f 3c 48 89 d8 48 c1 e8 03 <42> 0f b6 04 30 84 c0 0f 85 10 02 00 00 44 8b 23 4c 89 e7 48 c7 c6
RSP: 0018:ffffc90000d36ec8 EFLAGS: 00000a03
RAX: 1ffff11028959807 RBX: ffff888144acc03c RCX: 0000000000080000
RDX: ffffc900021c4000 RSI: 000000000007ffff RDI: ffff888144acc0c8
RBP: ffffc90000d36f10 R08: ffff8881108513c0 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000002 R12: 00000000fffffff1
R13: ffff888144acc0cc R14: dffffc0000000000 R15: ffff888144acc000
FS:  00007f9441f366c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2f723ffc CR3: 0000000135fa7000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 fq_codel_change+0xa8a/0xf70 net/sched/sch_fq_codel.c:436
 fq_codel_init+0x342/0xa20 net/sched/sch_fq_codel.c:473
 qdisc_create+0x803/0x11b0 net/sched/sch_api.c:1256
 tc_modify_qdisc+0x8ad/0x1570 net/sched/sch_api.c:-1
 rtnetlink_rcv_msg+0xa4b/0xce0 net/core/rtnetlink.c:5650
 netlink_rcv_skb+0x1f5/0x440 net/netlink/af_netlink.c:2511
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5668
 netlink_unicast_kernel net/netlink/af_netlink.c:1322 [inline]
 netlink_unicast+0x876/0xa40 net/netlink/af_netlink.c:1348
 netlink_sendmsg+0x879/0xb80 net/netlink/af_netlink.c:1922
 sock_sendmsg_nosec net/socket.c:704 [inline]
 __sock_sendmsg net/socket.c:716 [inline]
 ____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2435
 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2489
 __sys_sendmsg net/socket.c:2518 [inline]
 __do_sys_sendmsg net/socket.c:2527 [inline]
 __se_sys_sendmsg net/socket.c:2525 [inline]
 __x64_sys_sendmsg+0x206/0x2f0 net/socket.c:2525
 x64_sys_call+0x4b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f94434d9eb9
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:00007f9441f36028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f9443754fa0 RCX: 00007f94434d9eb9
RDX: 0000000000008840 RSI: 0000200000000740 RDI: 0000000000000003
RBP: 00007f9443547c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9443755038 R14: 00007f9443754fa0 R15: 00007ffeca212668
 </TASK>
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:51 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 0 skipped: idling at default_idle+0xf/0x20 arch/x86/kernel/process.c:729