bisecting cause commit starting from fcadab740480e0e0e9fa9bd272acd409884d431a building syzkaller on 9602ddf403bdf3cfd87efef14becc76f9a38b81d testing commit fcadab740480e0e0e9fa9bd272acd409884d431a with gcc (GCC) 8.1.0 kernel signature: f4b978245fc5eacd3001ef5ae9d19197d51a809da2efcca6c69ffcc188ccb02e all runs: crashed: WARNING in get_signal testing release v5.8 testing commit bcf876870b95592b52519ed4aafcf9d95999bc9c with gcc (GCC) 8.1.0 kernel signature: 08089a676a35aaf2ddc6cceedace1a81a71d6c25c0110417e915bb5c92cb72d7 all runs: crashed: WARNING in get_signal testing release v5.7 testing commit 3d77e6a8804abcc0504c904bd6e5cdf3a5cf8162 with gcc (GCC) 8.1.0 kernel signature: f283eae82fe4bf2c8d2b8460252a12eee81f01d827d2965ec8646c9af388762e all runs: crashed: WARNING in get_signal testing release v5.6 testing commit 7111951b8d4973bda27ff663f2cf18b663d15b48 with gcc (GCC) 8.1.0 kernel signature: 3a728d3878ba5b87d38314e1d7f01e3da73d37a9b56fb28597d7ebaf045099e8 all runs: crashed: WARNING in get_signal testing release v5.5 testing commit d5226fa6dbae0569ee43ecfc08bdcd6770fc4755 with gcc (GCC) 8.1.0 kernel signature: 6400aa19af4eb4ad001ccd5e08d23dea06dccf5d7bef260c50011072c831321e all runs: crashed: WARNING in get_signal testing release v5.4 testing commit 219d54332a09e8d8741c1e1982f5eae56099de85 with gcc (GCC) 8.1.0 kernel signature: 9c890214fb54b4241bd445c9c9e45098132bc0a98c3a91e2289954b4c269f1b1 all runs: crashed: WARNING in get_signal testing release v5.3 testing commit 4d856f72c10ecb060868ed10ff1b1453943fc6c8 with gcc (GCC) 8.1.0 kernel signature: 174c7b48ec3702a1dfd15ec84f6c3e8d14bf501b83cd393acaa9920fdfef28b1 all runs: crashed: WARNING in get_signal testing release v5.2 testing commit 0ecfebd2b52404ae0c54a878c872bb93363ada36 with gcc (GCC) 8.1.0 kernel signature: 5e2c754c0d0745206b58c263339684c0a653d05103f7679df7138ec6c82c29c6 all runs: crashed: WARNING in get_signal testing release v5.1 testing commit e93c9c99a629c61837d5a7fc2120cd2b6c70dbdd with gcc (GCC) 8.1.0 kernel signature: 16de38e2fb141ed61462a1cc5a0ebba4cb83a3dcebda0779842a277705d7df87 all runs: crashed: WARNING in get_signal testing release v5.0 testing commit 1c163f4c7b3f621efff9b28a47abb36f7378d783 with gcc (GCC) 8.1.0 kernel signature: b772d0d309d487d276719ada6c0e500a1f0743d3df45927bfa6e90221bbb36b6 all runs: crashed: WARNING in get_signal testing release v4.20 testing commit 8fe28cb58bcb235034b64cbbb7550a8a43fd88be with gcc (GCC) 8.1.0 kernel signature: d4f268559e060291540a28a5818da6a8f1f68a2b23e7c30ac810e94e16ee5ddc all runs: crashed: WARNING in get_signal testing release v4.19 testing commit 84df9525b0c27f3ebc2ebb1864fa62a97fdedb7d with gcc (GCC) 8.1.0 kernel signature: 49ec93301d6b6c762ee8fe366b1f094b468d7f1d8ceb00722e24c1e52d944230 all runs: crashed: WARNING in get_signal testing release v4.18 testing commit 94710cac0ef4ee177a63b5227664b38c95bbf703 with gcc (GCC) 8.1.0 kernel signature: c63c1c9a6c5bb1a26e9335f88b5d7374ed5591aae139d9e4969ad2ae9bcd1158 all runs: crashed: WARNING in get_signal testing release v4.17 testing commit 29dcea88779c856c7dc92040a0c01233263101d4 with gcc (GCC) 8.1.0 kernel signature: e162d8366fd569b1281c559627e4c723a51de6648d05da7aa6ecd104ce60a8f9 all runs: crashed: WARNING in get_signal testing release v4.16 testing commit 0adb32858b0bddf4ada5f364a84ed60b196dbcda with gcc (GCC) 8.1.0 kernel signature: 0b02665344e79184fdaeee47e69437552265baf6de362968565c4c7df4768472 all runs: crashed: WARNING in get_signal testing release v4.15 testing commit d8a5b80568a9cb66810e75b182018e9edb68e8ff with gcc (GCC) 8.1.0 kernel signature: e585e1890abcffd84b73bd6213afdd4c3133c06557ff8354077d6210526ec922 all runs: crashed: WARNING in get_signal testing release v4.14 testing commit bebc6082da0a9f5d47a1ea2edc099bf671058bd4 with gcc (GCC) 8.1.0 kernel signature: 4c33c50b92c421b88d9a9495265c127ac09cf60b79ba2f262b71ed0e7de94fae all runs: crashed: WARNING in get_signal testing release v4.13 testing commit 569dbb88e80deb68974ef6fdd6a13edb9d686261 with gcc (GCC) 8.1.0 kernel signature: 21d29984779ef1d9899410b75c18d242574e9c9ead419b2e81f78d6d883bffc0 all runs: crashed: WARNING in get_signal testing release v4.12 testing commit 6f7da290413ba713f0cdd9ff1a2a9bb129ef4f6c with gcc (GCC) 8.1.0 kernel signature: 7236e930ee90c10b1f8a7cc27d398a36d432e7f720848c1742814c94bad91bb4 all runs: crashed: BUG: sleeping function called from invalid context in tap_get_minor testing release v4.11 testing commit a351e9b9fc24e982ec2f0e76379a49826036da12 with gcc (GCC) 7.3.0 kernel signature: a2a3aca8dab898eb898000915ef53abe4a28736bdd03a327f0ac9bbb63aea0ce all runs: crashed: BUG: sleeping function called from invalid context in tap_get_minor testing release v4.10 testing commit c470abd4fde40ea6a0846a2beab642a578c0b8cd with gcc (GCC) 5.5.0 kernel signature: 2b2863cab16b25c415fd524de1aaf09553422d65b431179ef3b99dfca4aeb6db all runs: crashed: WARNING in get_signal testing release v4.9 testing commit 69973b830859bc6529a7a0468ba0d80ee5117826 with gcc (GCC) 5.5.0 kernel signature: 38976240b80cf03d620fbda99174203df59216b5751b7ecaf90101ae820c8cd3 all runs: crashed: WARNING in get_signal testing release v4.8 testing commit c8d2bc9bc39ebea8437fd974fdbc21847bb897a3 with gcc (GCC) 5.5.0 kernel signature: f5fc73506b15c76ff2d2a96fc12aba7bfa1b4e8db006de3b4b6a28deb4b5c7b3 all runs: crashed: WARNING in get_signal testing release v4.7 testing commit 523d939ef98fd712632d93a5a2b588e477a7565e with gcc (GCC) 5.5.0 kernel signature: 13f0a2c93ba69954823de5d6570007b4bd8672cfc3ec4a5872427dd5eb3f8e3b run #0: crashed: KASAN: null-ptr-deref Read run #1: crashed: WARNING in get_signal run #2: crashed: WARNING in get_signal run #3: crashed: WARNING in get_signal run #4: crashed: WARNING in get_signal run #5: crashed: WARNING in get_signal run #6: crashed: WARNING in get_signal run #7: crashed: WARNING in get_signal run #8: crashed: WARNING in get_signal run #9: crashed: WARNING in get_signal testing release v4.6 testing commit 2dcd0af568b0cf583645c8a317dd12e344b1c72a with gcc (GCC) 5.5.0 kernel signature: b2324e7f69e7c1c0154bf5890ebaf8bce672ebe5bbe938610beb3cee7a977aa7 all runs: crashed: WARNING in sysfs_warn_dup revisions tested: 25, total time: 3h58m58.888425908s (build: 2h28m15.605298799s, test: 1h26m45.641014347s) the crash already happened on the oldest tested release commit msg: Linux 4.6 crash: WARNING in sysfs_warn_dup device bridge_slave_1 entered promiscuous mode IPv6: ADDRCONF(NETDEV_UP): hsr_slave_0: link is not ready IPv6: ADDRCONF(NETDEV_UP): hsr_slave_1: link is not ready bond0: Enslaving bond_slave_0 as an active interface with an up link ------------[ cut here ]------------ WARNING: CPU: 1 PID: 5943 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x7b/0xa0 fs/sysfs/dir.c:30 sysfs: cannot create duplicate filename '/class/macvtap/tap50' Kernel panic - not syncing: panic_on_warn set ... CPU: 1 PID: 5943 Comm: syz-executor.4 Not tainted 4.6.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 0000000000000000 ffff8800b2636fc8 ffffffff82e18b12 ffffffff85e81040 ffff8800b26370a0 ffffffff85f2bc00 ffffffff8191bd7b 0000000000000009 ffff8800b2637090 ffffffff8160d884 0000000041b58ab3 ffffffff86b4158a Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0x136/0x1d4 lib/dump_stack.c:51 [] panic+0x1af/0x348 kernel/panic.c:152 [] __warn+0x18d/0x1b0 kernel/panic.c:504 [] warn_slowpath_fmt+0x92/0xb0 kernel/panic.c:527 [] sysfs_warn_dup+0x7b/0xa0 fs/sysfs/dir.c:30 [] sysfs_do_create_link_sd.isra.0+0xd1/0xf0 fs/sysfs/symlink.c:51 [] sysfs_do_create_link fs/sysfs/symlink.c:80 [inline] [] sysfs_create_link+0x43/0xb0 fs/sysfs/symlink.c:92 [] device_add_class_symlinks drivers/base/core.c:891 [inline] [] device_add+0x677/0x1350 drivers/base/core.c:1086 [] device_create_groups_vargs+0x1c8/0x220 drivers/base/core.c:1709 [] device_create_vargs drivers/base/core.c:1749 [inline] [] device_create+0x88/0xa0 drivers/base/core.c:1785 [] macvtap_device_event+0x1c4/0x2a0 drivers/net/macvtap.c:1298 [] notifier_call_chain+0x8b/0x170 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+0x47/0x80 net/core/dev.c:1643 [] call_netdevice_notifiers net/core/dev.c:1659 [inline] [] register_netdevice+0x8e8/0xd00 net/core/dev.c:7027 [] macvlan_common_newlink+0x8b9/0x1090 drivers/net/macvlan.c:1316 [] macvtap_newlink+0xbf/0x110 drivers/net/macvtap.c:471 [] rtnl_newlink+0xd4b/0x1230 net/core/rtnetlink.c:2466 [] rtnetlink_rcv_msg+0x222/0x680 net/core/rtnetlink.c:3513 [] netlink_rcv_skb+0x242/0x350 net/netlink/af_netlink.c:2277 [] rtnetlink_rcv+0x25/0x30 net/core/rtnetlink.c:3519 [] netlink_unicast_kernel net/netlink/af_netlink.c:1214 [inline] [] netlink_unicast+0x3da/0x560 net/netlink/af_netlink.c:1240 [] netlink_sendmsg+0x9bb/0xb40 net/netlink/af_netlink.c:1786 [] sock_sendmsg_nosec net/socket.c:612 [inline] [] sock_sendmsg+0xb5/0xf0 net/socket.c:622 [] SYSC_sendto net/socket.c:1648 [inline] [] SyS_sendto+0x1ca/0x290 net/socket.c:1616 [] entry_SYSCALL_64_fastpath+0x23/0xc1 Kernel Offset: disabled