bisecting fixing commit since e0f8b8a65a473a8baa439cf865a694bbeb83fe90 building syzkaller on 35f5e45ed3cc032d9f969f3a8700e29607c1364f testing commit e0f8b8a65a473a8baa439cf865a694bbeb83fe90 with gcc (GCC) 8.1.0 kernel signature: a1ba315136c4ba3c188eb4d99016b5eb398f8793e3571b37709908cd747ebcce run #0: crashed: WARNING in batadv_iv_send_outstanding_bat_ogm_packet run #1: crashed: WARNING in batadv_iv_send_outstanding_bat_ogm_packet run #2: crashed: WARNING in batadv_iv_send_outstanding_bat_ogm_packet run #3: crashed: WARNING in corrupted run #4: crashed: WARNING in corrupted run #5: crashed: WARNING in corrupted run #6: crashed: WARNING in process_one_work run #7: crashed: WARNING in batadv_iv_send_outstanding_bat_ogm_packet run #8: OK run #9: OK testing current HEAD d71f695ce745df9544a85d8a762f16d72e72df00 testing commit d71f695ce745df9544a85d8a762f16d72e72df00 with gcc (GCC) 8.1.0 kernel signature: 2537abf79d612ff9f55fe21991e666074b1006c83bb91d2fdd942733f9bfeefd run #0: crashed: WARNING in batadv_iv_send_outstanding_bat_ogm_packet run #1: crashed: WARNING in batadv_iv_send_outstanding_bat_ogm_packet run #2: crashed: WARNING in corrupted run #3: crashed: WARNING in corrupted run #4: crashed: WARNING in batadv_iv_send_outstanding_bat_ogm_packet run #5: crashed: WARNING in corrupted run #6: crashed: WARNING in process_one_work run #7: OK run #8: OK run #9: OK revisions tested: 2, total time: 41m15.445392783s (build: 17m38.614518019s, test: 21m58.784619855s) the crash still happens on HEAD commit msg: Linux 4.14.179 crash: WARNING in process_one_work slab_pre_alloc_hook mm/slab.h:421 [inline] slab_alloc_node mm/slab.c:3297 [inline] kmem_cache_alloc_node_trace+0x279/0x780 mm/slab.c:3659 __do_kmalloc_node mm/slab.c:3681 [inline] __kmalloc_node_track_caller+0x3c/0x70 mm/slab.c:3696 __kmalloc_reserve.isra.38+0x2c/0xc0 net/core/skbuff.c:137 ------------[ cut here ]------------ __alloc_skb+0xc1/0x500 net/core/skbuff.c:205 WARNING: CPU: 1 PID: 22 at net/batman-adv/bat_iv_ogm.c:588 batadv_iv_send_outstanding_bat_ogm_packet+0x633/0x7c0 net/batman-adv/bat_iv_ogm.c:1835 alloc_skb include/linux/skbuff.h:980 [inline] nlmsg_new include/net/netlink.h:511 [inline] rtmsg_ifinfo_build_skb+0x68/0x120 net/core/rtnetlink.c:2908 Kernel panic - not syncing: panic_on_warn set ... rtmsg_ifinfo_event.part.27+0x16/0xb0 net/core/rtnetlink.c:2942 rtmsg_ifinfo_event net/core/rtnetlink.c:4366 [inline] rtnetlink_event+0xc2/0x110 net/core/rtnetlink.c:4359 notifier_call_chain+0xd6/0x150 kernel/notifier.c:93 __raw_notifier_call_chain kernel/notifier.c:394 [inline] raw_notifier_call_chain+0x11/0x20 kernel/notifier.c:401 call_netdevice_notifiers_info+0x4b/0x60 net/core/dev.c:1671 __netdev_upper_dev_link+0x18e/0x1f0 net/core/dev.c:6324 netdev_master_upper_dev_link+0x14/0x20 net/core/dev.c:6372 batadv_hardif_enable_interface+0x1f4/0xa10 net/batman-adv/hard-interface.c:747 batadv_softif_slave_add+0x7f/0xd0 net/batman-adv/soft-interface.c:889 do_set_master+0x163/0x1f0 net/core/rtnetlink.c:1961 do_setlink+0x9dd/0x2c50 net/core/rtnetlink.c:2098 rtnl_newlink+0xe0c/0x1390 net/core/rtnetlink.c:2660 rtnetlink_rcv_msg+0x34c/0x9e0 net/core/rtnetlink.c:4315 netlink_rcv_skb+0x133/0x370 net/netlink/af_netlink.c:2433 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:4327 netlink_unicast_kernel net/netlink/af_netlink.c:1287 [inline] netlink_unicast+0x40b/0x600 net/netlink/af_netlink.c:1313 netlink_sendmsg+0x730/0xbd0 net/netlink/af_netlink.c:1878 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xb5/0xf0 net/socket.c:656 ___sys_sendmsg+0x625/0x920 net/socket.c:2062 __sys_sendmsg+0xc1/0x140 net/socket.c:2096 SYSC_sendmsg net/socket.c:2107 [inline] SyS_sendmsg+0xd/0x20 net/socket.c:2103 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x4436d9 RSP: 002b:00007ffc17a6a418 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004436d9 RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000002 R09: 00000000bb1414ac R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff R13: 0000000000000006 R14: 0000000000000000 R15: 0000000000000000 CPU: 1 PID: 22 Comm: kworker/u4:1 Not tainted 4.14.179-syzkaller #0 batman_adv: batadv0: Adding interface: veth0_to_bridge Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xf7/0x13b lib/dump_stack.c:58 batman_adv: batadv0: The MTU of interface veth0_to_bridge is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1560 would solve the problem. 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 batman_adv: batadv0: Interface activated: veth0_to_bridge do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:963 RIP: 0010:batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:588 [inline] RIP: 0010:batadv_iv_send_outstanding_bat_ogm_packet+0x633/0x7c0 net/batman-adv/bat_iv_ogm.c:1847 RSP: 0018:ffff8880a9ec7ce0 EFLAGS: 00010286 RAX: ffff8880910f4040 RBX: ffff88808d96a088 RCX: 1ffff110126b4dc6 RDX: 0000000000000000 RSI: ffffffff87f84ea0 RDI: ffff8880935a6e30 RBP: ffff8880a9ec7d60 R08: ffff8880a9ebce90 R09: 0000000000004f97 R10: 0000000000000028 R11: ffff8880a9ebc5c0 R12: ffff888079750400 R13: ffff88808d96a040 R14: ffff8880935a6dc0 R15: ffff88808d96a128 process_one_work+0x79e/0x16c0 kernel/workqueue.c:2116 worker_thread+0xcc/0xee0 kernel/workqueue.c:2250 kthread+0x338/0x400 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Kernel Offset: disabled Rebooting in 86400 seconds..