syzbot has found a reproducer for the following issue on: HEAD commit: 6fbd15c0 Merge branch '100GbE' of git://git.kernel.org/pub.. git tree: net console output: https://syzkaller.appspot.com/x/log.txt?x=17a009a8d00000 kernel config: https://syzkaller.appspot.com/x/.config?x=2b8307379601586a dashboard link: https://syzkaller.appspot.com/bug?extid=9b658439133becd38da1 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=101ff9b6d00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14c9a5cad00000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+9b658439133becd38da1@xxxxxxxxxxxxxxxxxxxxxxxxx RBP: 0000000000403430 R08: 00000000004004a0 R09: 00000000004004a0 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004034c0 R13: 0000000000000000 R14: 00000000004ad018 R15: 00000000004004a0 kobject_add_internal failed for 43:0 with -EEXIST, don't try to register things with the same name in the same directory. ------------[ cut here ]------------ WARNING: CPU: 0 PID: 8421 at block/genhd.c:620 __device_add_disk+0x1030/0x1300 block/genhd.c:620 Modules linked in: CPU: 0 PID: 8421 Comm: syz-executor614 Not tainted 5.11.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__device_add_disk+0x1030/0x1300 block/genhd.c:620 Code: f1 ff ff e8 42 c4 c1 fd 0f 0b e9 e6 f6 ff ff 48 89 7c 24 20 e8 31 c4 c1 fd 0f 0b 48 8b 7c 24 20 e9 9b f4 ff ff e8 20 c4 c1 fd <0f> 0b e9 dd fb ff ff 4c 89 ef e8 a1 fc 04 fe e9 28 f1 ff ff 48 8b RSP: 0018:ffffc9000163f340 EFLAGS: 00010293 RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000 RDX: ffff888015548000 RSI: ffffffff83b11590 RDI: 0000000000000003 RBP: ffff888025956000 R08: 0000000000000000 R09: ffffffff8fa9a837 R10: ffffffff83b1116b R11: 0000000000000000 R12: 00000000ffffffef R13: ffff8880259560a0 R14: ffff888016fa97d0 R15: ffff8880171ae000 FS: 0000000001b2c300(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020000380 CR3: 0000000015534000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: add_disk include/linux/genhd.h:231 [inline] nbd_dev_add+0x720/0x910 drivers/block/nbd.c:1719 nbd_genl_connect+0x557/0x1570 drivers/block/nbd.c:1829 genl_family_rcv_msg_doit+0x228/0x320 net/netlink/genetlink.c:739 genl_family_rcv_msg net/netlink/genetlink.c:783 [inline] genl_rcv_msg+0x328/0x580 net/netlink/genetlink.c:800 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2502 genl_rcv+0x24/0x40 net/netlink/genetlink.c:811 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline] netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1338 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1927 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2348 ___sys_sendmsg+0xf3/0x170 net/socket.c:2402 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2435 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x43f9c9 Code: 28 c3 e8 5a 14 00 00 66 2e 0f 1f 84 00 00 00 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 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffd2bb97998 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00000000004004a0 RCX: 000000000043f9c9 RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000004 RBP: 0000000000403430 R08: 00000000004004a0 R09: 00000000004004a0 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004034c0 R13: 0000000000000000 R14: 00000000004ad018 R15: 00000000004004a0
