============================= WARNING: suspicious RCU usage syzkaller #0 Not tainted ----------------------------- ./include/net/sch_generic.h:581 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 2 locks held by syz.0.51/6016: #0: ffffffff8e75e640 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #0: ffffffff8e75e640 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:903 [inline] #0: ffffffff8e75e640 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x277/0x3890 net/core/dev.c:4778 #1: ffff8881ad9e8170 (&sch->root_lock_key#31){+...}-{3:3}, at: spin_lock include/linux/spinlock.h:341 [inline] #1: ffff8881ad9e8170 (&sch->root_lock_key#31){+...}-{3:3}, at: __dev_xmit_skb net/core/dev.c:4241 [inline] #1: ffff8881ad9e8170 (&sch->root_lock_key#31){+...}-{3:3}, at: __dev_queue_xmit+0xbf2/0x3890 net/core/dev.c:4819 stack backtrace: CPU: 1 UID: 0 PID: 6016 Comm: syz.0.51 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 lockdep_rcu_suspicious+0x13f/0x1d0 kernel/locking/lockdep.c:6876 qdisc_root_sleeping include/net/sch_generic.h:581 [inline] qdisc_dequeue_drop include/net/sch_generic.h:1173 [inline] cake_dequeue+0x23a7/0x4e50 net/sched/sch_cake.c:2240 dequeue_skb net/sched/sch_generic.c:297 [inline] qdisc_restart net/sched/sch_generic.c:402 [inline] __qdisc_run+0x26c/0x15d0 net/sched/sch_generic.c:420 qdisc_run include/net/pkt_sched.h:120 [inline] __dev_xmit_skb net/core/dev.c:4286 [inline] __dev_queue_xmit+0x1bad/0x3890 net/core/dev.c:4819 packet_snd net/packet/af_packet.c:3076 [inline] packet_sendmsg+0x3eb6/0x50f0 net/packet/af_packet.c:3108 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] __sys_sendto+0x672/0x710 net/socket.c:2206 __do_sys_sendto net/socket.c:2213 [inline] __se_sys_sendto net/socket.c:2209 [inline] __x64_sys_sendto+0xde/0x100 net/socket.c:2209 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f077b39c819 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:00007f077c28c028 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f077b615fa0 RCX: 00007f077b39c819 RDX: 000000000000fc13 RSI: 0000200000000800 RDI: 0000000000000003 RBP: 00007f077b432c91 R08: 0000000000000000 R09: fffffffffffffef0 R10: 0000000000000880 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f077b616038 R14: 00007f077b615fa0 R15: 00007fffceb20038