syzbot

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc48c7e6218 R14: 00007fc48c7e6180 R15: 00007ffec3651ac8
 </TASK>
watchdog: BUG: soft lockup - CPU#1 stuck for 246s! [syz.8.3792:15176]
Modules linked in:
CPU: 1 PID: 15176 Comm: syz.8.3792 Tainted: G        W          syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:qdisc_tree_reduce_backlog+0x238/0x360 net/sched/sch_api.c:816
Code: bc 6f 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 <49> 8d bd c4 00 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f
RSP: 0018:ffffc900013bee28 EFLAGS: 00000246
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000080000
RDX: ffffc9000b680000 RSI: 000000000007ffff RDI: ffff8881569314a8
RBP: ffffc900013bee70 R08: ffff88813f4b6540 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000002 R12: 00000000fffffff1
R13: ffff888156931400 R14: dffffc0000000000 R15: ffff888156931400
FS:  00007fc48aff76c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b34f1cff8 CR3: 0000000132588000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 00000000000f000d DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 fq_codel_change+0xafd/0x1010 net/sched/sch_fq_codel.c:440
 fq_codel_init+0x384/0xa90 net/sched/sch_fq_codel.c:477
 qdisc_create+0x7f3/0x1040 net/sched/sch_api.c:1316
 tc_modify_qdisc+0x8ea/0x19b0 net/sched/sch_api.c:-1
 rtnetlink_rcv_msg+0x9f4/0xcf0 net/core/rtnetlink.c:6153
 netlink_rcv_skb+0x1f2/0x440 net/netlink/af_netlink.c:2521
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6171
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x8ab/0xa30 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x8aa/0xbc0 net/netlink/af_netlink.c:1873
 sock_sendmsg_nosec net/socket.c:716 [inline]
 __sock_sendmsg net/socket.c:728 [inline]
 ____sys_sendmsg+0x5a9/0x990 net/socket.c:2509
 ___sys_sendmsg+0x21c/0x290 net/socket.c:2563
 __sys_sendmsg net/socket.c:2592 [inline]
 __do_sys_sendmsg net/socket.c:2601 [inline]
 __se_sys_sendmsg net/socket.c:2599 [inline]
 __x64_sys_sendmsg+0x1f0/0x2c0 net/socket.c:2599
 x64_sys_call+0x171/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc48c58f749
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:00007fc48aff7038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fc48c7e6180 RCX: 00007fc48c58f749
RDX: 0000000000000000 RSI: 0000200000000000 RDI: 0000000000000006
RBP: 00007fc48c613f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc48c7e6218 R14: 00007fc48c7e6180 R15: 00007ffec3651ac8
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 1216 Comm: kworker/u4:10 Tainted: G        W          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:453 [inline]
RIP: 0010:smp_call_function_many_cond+0x872/0x960 kernel/smp.c:998
Code: 41 8b 1f 89 de 83 e6 01 31 ff e8 99 65 09 00 83 e3 01 48 bb 00 00 00 00 00 fc ff df 75 0a e8 65 61 09 00 e9 38 ff ff ff f3 90 <41> 0f b6 44 1d 00 84 c0 75 14 41 f7 07 01 00 00 00 0f 84 1a ff ff
RSP: 0018:ffffc90001157840 EFLAGS: 00000293
RAX: ffffffff8166c93e RBX: dffffc0000000000 RCX: ffff88811584d100
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90001157978 R08: dffffc0000000000 R09: ffffed103ee0721b
R10: 0000000000000000 R11: ffffffff81343830 R12: 1ffff1103ee07218
R13: 1ffff1103ee278a5 R14: 0000000000000001 R15: ffff8881f713c528
FS:  0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000556ef0390338 CR3: 0000000006e0f000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 00000000000f000d DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x43/0x80 kernel/smp.c:1165
 on_each_cpu include/linux/smp.h:71 [inline]
 text_poke_sync arch/x86/kernel/alternative.c:1574 [inline]
 text_poke_bp_batch+0x1cc/0x580 arch/x86/kernel/alternative.c:1774
 text_poke_flush arch/x86/kernel/alternative.c:1965 [inline]
 text_poke_finish+0x1a/0x30 arch/x86/kernel/alternative.c:1972
 arch_jump_label_transform_apply+0x15/0x30 arch/x86/kernel/jump_label.c:146
 __jump_label_update+0x37c/0x3a0 kernel/jump_label.c:451
 jump_label_update+0x39b/0x450 kernel/jump_label.c:797
 static_key_disable_cpuslocked+0xc9/0x1a0 kernel/jump_label.c:203
 static_key_disable+0x1a/0x30 kernel/jump_label.c:211
 toggle_allocation_gate+0x363/0x400 mm/kfence/core.c:819
 process_one_work+0x71f/0xc40 kernel/workqueue.c:2302
 worker_thread+0xa29/0x11f0 kernel/workqueue.c:2449
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>