watchdog: BUG: soft lockup - CPU#1 stuck for 266s! [syz.5.1340:5508]
Modules linked in:
CPU: 1 PID: 5508 Comm: syz.5.1340 Tainted: G        W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:qdisc_dev include/net/sch_generic.h:596 [inline]
RIP: 0010:qdisc_match_from_root net/sched/sch_api.c:263 [inline]
RIP: 0010:qdisc_lookup+0x2a0/0x4e0 net/sched/sch_api.c:309
Code: 36 4d 8d 7e 40 4c 89 f8 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 ff e8 2f 61 ce fd 4d 8b 3f 4c 89 f8 48 c1 e8 03 42 80 3c 28 00 <74> 08 4c 89 ff e8 16 61 ce fd 4d 8b 27 4d 85 e4 74 6c 4d 8d 7e 10
RSP: 0018:ffffc90000e4ee88 EFLAGS: 00000246
RAX: 1ffff11025177800 RBX: 00000000ffff0000 RCX: 0000000000080000
RDX: ffffc9000678d000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: ffffc90000e4eeb8 R08: ffff8881163d62c0 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000002 R12: 0000000000040000
R13: dffffc0000000000 R14: ffff888128bbcc00 R15: ffff888128bbc000
FS:  00007fd4a02936c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd4a0292ff8 CR3: 000000011bcd8000 CR4: 00000000003506a0
Call Trace:
 <TASK>
 qdisc_tree_reduce_backlog+0x111/0x340 net/sched/sch_api.c:784
 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: 0033:0x7fd4a1838819
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:00007fd4a0293028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fd4a1ab1fa0 RCX: 00007fd4a1838819
RDX: 0000000000008840 RSI: 0000200000000740 RDI: 0000000000000003
RBP: 00007fd4a18cec91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd4a1ab2038 R14: 00007fd4a1ab1fa0 R15: 00007ffe47bfbed8
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 10 Comm: kworker/u4:1 Tainted: G        W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:csd_lock_wait kernel/smp.c:440 [inline]
RIP: 0010:smp_call_function_many_cond+0x8e3/0xa10 kernel/smp.c:969
Code: 84 c0 0f 85 9d 00 00 00 41 8b 1f 89 de 83 e6 01 31 ff e8 e0 4e 0a 00 83 e3 01 48 8b 5c 24 10 75 07 e8 21 4b 0a 00 eb 42 f3 90 <48> b8 00 00 00 00 00 fc ff df 41 0f b6 44 05 00 84 c0 75 10 41 f7
RSP: 0018:ffffc900000a7860 EFLAGS: 00000293
RAX: ffffffff815f7be5 RBX: ffff8881f7038e80 RCX: ffff888100274f00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900000a7978 R08: ffff8881f7038e97 R09: 1ffff1103ee071d2
R10: dffffc0000000000 R11: ffffed103ee071d3 R12: 1ffff1103ee071d0
R13: 1ffff1103ee2784d R14: 0000000000000001 R15: ffff8881f713c268
FS:  0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f87c60341e8 CR3: 000000000660f000 CR4: 00000000003506b0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x43/0x80 kernel/smp.c:1134
 on_each_cpu include/linux/smp.h:71 [inline]
 text_poke_sync arch/x86/kernel/alternative.c:1442 [inline]
 text_poke_bp_batch+0x1d4/0x600 arch/x86/kernel/alternative.c:1642
 text_poke_flush arch/x86/kernel/alternative.c:1833 [inline]
 text_poke_finish+0x1a/0x30 arch/x86/kernel/alternative.c:1840
 arch_jump_label_transform_apply+0x15/0x30 arch/x86/kernel/jump_label.c:146
 __jump_label_update+0x37c/0x3a0 kernel/jump_label.c:459
 jump_label_update+0x39b/0x450 kernel/jump_label.c:830
 static_key_disable_cpuslocked+0xc5/0x1a0 kernel/jump_label.c:207
 static_key_disable+0x1a/0x30 kernel/jump_label.c:215
 toggle_allocation_gate+0x3af/0x440 mm/kfence/core.c:797
 process_one_work+0x6be/0xba0 kernel/workqueue.c:2325
 worker_thread+0xa59/0x1200 kernel/workqueue.c:2472
 kthread+0x411/0x500 kernel/kthread.c:337
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>