syzbot

watchdog: BUG: soft lockup - CPU#1 stuck for 123s! [syz.2.17:374]
Modules linked in:
CPU: 1 PID: 374 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:check_kcov_mode kernel/kcov.c:165 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:218 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x30/0x90 kernel/kcov.c:284
Code: 45 08 65 48 8b 15 70 b3 9d 7e 65 8b 0d 75 b3 9d 7e f7 c1 00 01 ff 00 74 11 f7 c1 00 01 00 00 74 5b 83 ba dc 0a 00 00 00 74 52 <8b> 8a b8 0a 00 00 83 f9 03 75 47 48 8b 8a c0 0a 00 00 44 8b 8a bc
RSP: 0018:ffffc90003a46f18 EFLAGS: 00000246
RAX: ffffffff83b29977 RBX: dffffc0000000000 RCX: 0000000000000201
RDX: ffff888110c7a780 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003a46f18 R08: ffff888110c7a780 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000000 R12: 00000000fffffff1
R13: ffff888110d1dc00 R14: ffff888110d1f000 R15: ffff888110d1dc40
FS:  000055558a23f500(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f77a931cd40 CR3: 000000010ff67000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 qdisc_tree_reduce_backlog+0x127/0x340 net/sched/sch_api.c:781
 fq_change+0xbdb/0x1100 net/sched/sch_fq.c:915
 fq_init+0x3e3/0x5d0 net/sched/sch_fq.c:963
 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: 0033:0x7f77a92cf629
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:00007ffd8eab81e8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f77a9548fa0 RCX: 00007f77a92cf629
RDX: 0000000020040080 RSI: 0000200000001200 RDI: 0000000000000005
RBP: 00007f77a9365b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f77a9548fac R14: 00007f77a9548fa0 R15: 00007f77a9548fa0
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