bisecting fixing commit since 8bac50406cca10a219aa899243d49c57ddaf7c5b building syzkaller on 2e95ab335759ed7e1c246c2057c84d813a2c29e1 testing commit 8bac50406cca10a219aa899243d49c57ddaf7c5b with gcc (GCC) 8.1.0 kernel signature: 8339110673980bc8432d6525f879b2d7c61b251911f110ae6aba85fbf706a84d all runs: crashed: WARNING in cbq_destroy_class testing current HEAD 98db2bf27b9ed2d5ed0b6c9c8a4bfcb127a19796 testing commit 98db2bf27b9ed2d5ed0b6c9c8a4bfcb127a19796 with gcc (GCC) 8.1.0 kernel signature: 45d6c07b2080ed098a5e77d6561e980cc43552d7517c1542e0fca702aa75c3a7 all runs: crashed: WARNING in cbq_destroy_class revisions tested: 2, total time: 26m3.976347661s (build: 18m1.836113801s, test: 7m15.498539076s) the crash still happens on HEAD commit msg: Linux 4.14.171 crash: WARNING in cbq_destroy_class IPv6: ADDRCONF(NETDEV_UP): veth1_macvtap: link is not ready IPv6: ADDRCONF(NETDEV_CHANGE): veth1_macvtap: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): veth0_macvtap: link becomes ready netlink: 96 bytes leftover after parsing attributes in process `syz-executor.3'. ------------[ cut here ]------------ WARNING: CPU: 0 PID: 7527 at net/sched/sch_cbq.c:1428 cbq_destroy_class+0xe4/0x110 net/sched/sch_cbq.c:1436 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 7527 Comm: syz-executor.3 Not tainted 4.14.171-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xf7/0x13b lib/dump_stack.c:58 panic+0x1b0/0x358 kernel/panic.c:183 __warn.cold.8+0x25/0x2c kernel/panic.c:547 report_bug+0x1a4/0x1f3 lib/bug.c:186 fixup_bug arch/x86/kernel/traps.c:177 [inline] do_error_trap+0x1bd/0x310 arch/x86/kernel/traps.c:295 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:963 RIP: 0010:cbq_destroy_class+0xe4/0x110 net/sched/sch_cbq.c:1428 RSP: 0018:ffff88807242f330 EFLAGS: 00010202 RAX: 0000000000000001 RBX: ffff8880a11a5520 RCX: ffff8880a41e0dc0 RDX: 1ffff11014234ac8 RSI: ffff8880a11a5520 RDI: ffff8880a11a5640 RBP: ffff88807242f340 R08: ffff8880a12c6908 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a11a5300 R13: 0000000000000000 R14: 0000000000000000 R15: ffffed1014234a98 cbq_destroy+0x1ff/0x2e0 net/sched/sch_cbq.c:1462 qdisc_destroy+0x119/0x2e0 net/sched/sch_generic.c:725 notify_and_destroy+0x34/0x40 net/sched/sch_api.c:885 qdisc_graft+0x350/0xca0 net/sched/sch_api.c:949 tc_modify_qdisc+0x8e9/0x13df net/sched/sch_api.c:1446 rtnetlink_rcv_msg+0x34c/0x9e0 net/core/rtnetlink.c:4315 netlink_rcv_skb+0x133/0x370 net/netlink/af_netlink.c:2432 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:4327 netlink_unicast_kernel net/netlink/af_netlink.c:1286 [inline] netlink_unicast+0x40b/0x600 net/netlink/af_netlink.c:1312 netlink_sendmsg+0x730/0xbd0 net/netlink/af_netlink.c:1877 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xb5/0xf0 net/socket.c:656 kernel_sendmsg+0x26/0x30 net/socket.c:664 sock_no_sendpage+0xf7/0x130 net/core/sock.c:2569 kernel_sendpage+0x60/0xd0 net/socket.c:3407 sock_sendpage+0x6d/0xd0 net/socket.c:871 pipe_to_sendpage+0x206/0x420 fs/splice.c:451 splice_from_pipe_feed fs/splice.c:502 [inline] __splice_from_pipe+0x2cb/0x720 fs/splice.c:626 splice_from_pipe+0xb5/0x110 fs/splice.c:661 generic_splice_sendpage+0x10/0x20 fs/splice.c:832 do_splice_from fs/splice.c:851 [inline] do_splice fs/splice.c:1147 [inline] SYSC_splice fs/splice.c:1402 [inline] SyS_splice+0x6e9/0x1580 fs/splice.c:1382 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45b349 RSP: 002b:00007efdea7f9c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000113 RAX: ffffffffffffffda RBX: 00007efdea7fa6d4 RCX: 000000000045b349 RDX: 0000000000000009 RSI: 0000000000000000 RDI: 0000000000000007 RBP: 000000000075bfc8 R08: 000000000004ffe0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000b3e R14: 00000000004ccc7e R15: 000000000075bfd4 Kernel Offset: disabled Rebooting in 86400 seconds..