bisecting cause commit starting from 7a56db0299f9d43b4fe076838150c5cc293df131 building syzkaller on 18397578713eeefc1cf3a687cca53594c1cfd49f testing commit 7a56db0299f9d43b4fe076838150c5cc293df131 with gcc (GCC) 8.1.0 kernel signature: 5ec689d19bbe34e97cd1dd0202e0c6f699cb949ce69d61f6669279b79a361c99 all runs: crashed: WARNING in cgroup_apply_control_disable testing release v5.6 testing commit 7111951b8d4973bda27ff663f2cf18b663d15b48 with gcc (GCC) 8.1.0 kernel signature: beae6e45e211e690adb5f7069708f3df4936e1d360afe1d305d7cad08da65cb6 all runs: crashed: WARNING in cgroup_apply_control_disable testing release v5.5 testing commit d5226fa6dbae0569ee43ecfc08bdcd6770fc4755 with gcc (GCC) 8.1.0 kernel signature: f84e03d1a22f17c5477ab962b2b4646cf0609463bc3ec8320ab3030f99cd153c all runs: crashed: WARNING in cgroup_apply_control_enable testing release v5.4 testing commit 219d54332a09e8d8741c1e1982f5eae56099de85 with gcc (GCC) 8.1.0 kernel signature: b9f69132cf9c2cf8e2ae994a3f9e80b11146d247dff6924af328d08cea6f3bdf all runs: crashed: WARNING in cgroup_apply_control_enable testing release v5.3 testing commit 4d856f72c10ecb060868ed10ff1b1453943fc6c8 with gcc (GCC) 8.1.0 kernel signature: 3d3b72d3613c62ce5951ec20373d781d8b2e7fa3724b15d7ebf377893807aa06 all runs: crashed: WARNING in cgroup_apply_control_enable testing release v5.2 testing commit 0ecfebd2b52404ae0c54a878c872bb93363ada36 with gcc (GCC) 8.1.0 kernel signature: b9ac8ee76b1172fd5ccefe3ce088eeaf0e5b85536e968a90f43d3233a898d0e2 all runs: crashed: WARNING in cgroup_apply_control_enable testing release v5.1 testing commit e93c9c99a629c61837d5a7fc2120cd2b6c70dbdd with gcc (GCC) 8.1.0 kernel signature: a65296cc668d72e9608d5c7b179ae78838ca2d23876cafd0cbc8d1f1b64e5eef run #0: crashed: WARNING in cgroup_apply_control_enable run #1: crashed: WARNING in cgroup_apply_control_enable run #2: crashed: WARNING in cgroup_apply_control_enable run #3: crashed: WARNING in cgroup_apply_control_enable run #4: crashed: WARNING in cgroup_apply_control_enable run #5: crashed: WARNING in cgroup_apply_control_enable run #6: crashed: WARNING in cgroup_apply_control_enable run #7: crashed: WARNING in cgroup_apply_control_enable run #8: crashed: WARNING in cgroup_apply_control_enable run #9: OK testing release v5.0 testing commit 1c163f4c7b3f621efff9b28a47abb36f7378d783 with gcc (GCC) 8.1.0 kernel signature: a011fe7d383a8d4a1f6e4728a14441d5c371d1f6bad5aface7ddc2d4873e9f4d all runs: crashed: WARNING in cgroup_apply_control_enable testing release v4.20 testing commit 8fe28cb58bcb235034b64cbbb7550a8a43fd88be with gcc (GCC) 8.1.0 kernel signature: f2f736282c2d650bfd2cdad67dc2660afa27f6e9c2456604bc592f52f1cb6766 all runs: crashed: WARNING in cgroup_apply_control_enable testing release v4.19 testing commit 84df9525b0c27f3ebc2ebb1864fa62a97fdedb7d with gcc (GCC) 8.1.0 kernel signature: ef3508404802b58b170f52a40191f8778927b33ee6cf0c5754a465e1d7f640c6 all runs: crashed: WARNING in cgroup_apply_control_enable testing release v4.18 testing commit 94710cac0ef4ee177a63b5227664b38c95bbf703 with gcc (GCC) 8.1.0 kernel signature: c673253d7d33eadab1245b088ee7875aa349c5028c866543bc159307b4897890 all runs: crashed: WARNING in cgroup_apply_control_enable testing release v4.17 testing commit 29dcea88779c856c7dc92040a0c01233263101d4 with gcc (GCC) 8.1.0 kernel signature: 10fe3ffb54f44c745410bfe2a2f82a56a59f67a9a0d7ad8dc824c684e1947cfb all runs: crashed: WARNING in cgroup_apply_control_enable testing release v4.16 testing commit 0adb32858b0bddf4ada5f364a84ed60b196dbcda with gcc (GCC) 8.1.0 kernel signature: 0d08cbd8ecb75d38b201a704586c47275a74cb9b2b5f4bf63a22a059b1ec5590 all runs: crashed: WARNING in cgroup_apply_control_enable testing release v4.15 testing commit d8a5b80568a9cb66810e75b182018e9edb68e8ff with gcc (GCC) 8.1.0 kernel signature: e9560571ad84d7fa54f7208fbc479b499938d723e896225865a0b139105bbca3 run #0: crashed: WARNING in cgroup_apply_control_enable run #1: crashed: WARNING in cgroup_apply_control_enable run #2: crashed: WARNING in cgroup_apply_control_enable run #3: crashed: WARNING in cgroup_apply_control_enable run #4: crashed: WARNING in cgroup_apply_control_enable run #5: crashed: WARNING in cgroup_apply_control_enable run #6: crashed: WARNING in cgroup_apply_control_enable run #7: crashed: WARNING in cgroup_apply_control_enable run #8: crashed: WARNING in cgroup_apply_control_enable run #9: crashed: no output from test machine testing release v4.14 testing commit bebc6082da0a9f5d47a1ea2edc099bf671058bd4 with gcc (GCC) 8.1.0 kernel signature: 0175c29dd8bc01d8fc7773c6f71da0beae2dd92c2e44cf712fa67e824b1c0182 run #0: crashed: WARNING in cgroup_apply_control_enable run #1: crashed: WARNING in cgroup_apply_control_enable run #2: crashed: WARNING in cgroup_apply_control_enable run #3: crashed: WARNING in cgroup_apply_control_enable run #4: crashed: WARNING in cgroup_apply_control_enable run #5: crashed: WARNING in cgroup_apply_control_enable run #6: crashed: WARNING in cgroup_apply_control_enable run #7: crashed: WARNING in cgroup_apply_control_enable run #8: crashed: WARNING in cgroup_apply_control_enable run #9: crashed: no output from test machine testing release v4.13 testing commit 569dbb88e80deb68974ef6fdd6a13edb9d686261 with gcc (GCC) 8.1.0 kernel signature: 2a59e1f608b170e708c1737f68a5ffbac8cbadc30216f2d96fa0cf956e6941c1 all runs: crashed: WARNING in cgroup_apply_control_enable testing release v4.12 testing commit 6f7da290413ba713f0cdd9ff1a2a9bb129ef4f6c with gcc (GCC) 8.1.0 kernel signature: 739bc92708090f925843ea8220b6b64b76655483c85b3c224ef325890252f5b0 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: 0c34b44338613aa6cc1fe67e16e4f0b67f6e102f7f26520bb06e5bf3c778ebd1 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: 60c42aab3d4a5dac2bb776e6c92b10c2f10ee5ed47573ad279019ccad1bca2e4 run #0: crashed: no output from test machine run #1: crashed: no output from test machine run #2: OK run #3: OK run #4: OK run #5: OK run #6: OK run #7: OK run #8: OK run #9: OK testing release v4.9 testing commit 69973b830859bc6529a7a0468ba0d80ee5117826 with gcc (GCC) 5.5.0 kernel signature: bb1148b44459b0e3fe1a48d1225109d11233a200cf5f9acf0a5d1755430202ef run #0: crashed: WARNING in nf_unregister_net_hook run #1: crashed: WARNING in nf_unregister_net_hook run #2: crashed: WARNING in nf_unregister_net_hook run #3: crashed: no output from test machine run #4: OK run #5: OK run #6: OK run #7: OK run #8: OK run #9: OK testing release v4.8 testing commit c8d2bc9bc39ebea8437fd974fdbc21847bb897a3 with gcc (GCC) 5.5.0 kernel signature: d266846b33bdef21066e37d155f9e1c617a6805f0b46fc180ff9e2ca2ce86467 run #0: crashed: INFO: task hung in __is_local_mountpoint run #1: crashed: INFO: task hung in SyS_umount run #2: crashed: BUG: workqueue lockup run #3: crashed: BUG: workqueue lockup run #4: crashed: INFO: task hung in SyS_umount run #5: crashed: INFO: task hung in __is_local_mountpoint run #6: crashed: INFO: task hung in SyS_umount run #7: crashed: INFO: task hung in __is_local_mountpoint run #8: crashed: INFO: task hung in __is_local_mountpoint run #9: OK testing release v4.7 testing commit 523d939ef98fd712632d93a5a2b588e477a7565e with gcc (GCC) 5.5.0 kernel signature: ce5fcf664b628af47fcdc389610a77b8e098594192bd32bb1b9f72b45c714134 run #0: crashed: INFO: rcu detected stall in do_signal run #1: crashed: INFO: task hung in SyS_umount run #2: crashed: INFO: task hung in SyS_umount run #3: crashed: INFO: task hung in __is_local_mountpoint run #4: crashed: INFO: task hung in SyS_umount run #5: crashed: BUG: soft lockup in corrupted run #6: crashed: INFO: task hung in __is_local_mountpoint run #7: crashed: INFO: task hung in do_unlinkat run #8: crashed: INFO: task hung in SyS_umount run #9: crashed: BUG: soft lockup in corrupted testing release v4.6 testing commit 2dcd0af568b0cf583645c8a317dd12e344b1c72a with gcc (GCC) 5.5.0 kernel signature: bb1fa01a5c6fa68bdb2cdf235dfb40462b709ddb8d86d2ebaad583c94ccd276a all runs: crashed: WARNING in sysfs_warn_dup revisions tested: 23, total time: 4h5m52.420428697s (build: 2h5m54.875955726s, test: 1h57m22.374766893s) the crash already happened on the oldest tested release commit msg: Linux 4.6 crash: WARNING in sysfs_warn_dup bridge0: port 2(bridge_slave_1) entered blocking state bridge0: port 2(bridge_slave_1) entered disabled state device bridge_slave_1 entered promiscuous mode bond0: Enslaving bond_slave_0 as an active interface with an up link ------------[ cut here ]------------ WARNING: CPU: 0 PID: 5868 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: 0 PID: 5868 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 ffff8800b1146fc8 ffffffff82c65932 ffffffff85c81040 ffff8800b11470a0 ffffffff85d2bb00 ffffffff8191b86b 0000000000000009 ffff8800b1147090 ffffffff8160d374 0000000041b58ab3 ffffffff868f058a 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