WARNING: possible circular locking dependency detected 4.13.0-rc6-next-20170825+ #9 Not tainted ------------------------------------------------------ syz-executor6/3924 is trying to acquire lock: (cpu_hotplug_lock.rw_sem){++++}, at: [] get_online_cpus include/linux/cpu.h:126 [inline] (cpu_hotplug_lock.rw_sem){++++}, at: [] flush_all_backlogs net/core/dev.c:4592 [inline] (cpu_hotplug_lock.rw_sem){++++}, at: [] rollback_registered_many+0x587/0xe80 net/core/dev.c:7127 but task is already holding lock: (rtnl_mutex){+.+.}, at: [] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:72 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (rtnl_mutex){+.+.}: check_prevs_add kernel/locking/lockdep.c:2020 [inline] validate_chain kernel/locking/lockdep.c:2469 [inline] __lock_acquire+0x3286/0x4620 kernel/locking/lockdep.c:3498 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4002 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1870 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 rtnl_lock+0x17/0x20 net/core/rtnetlink.c:72 addrconf_dad_work+0xbb/0xfc0 net/ipv6/addrconf.c:3890 process_one_work+0xbfd/0x1be0 kernel/workqueue.c:2098 worker_thread+0x223/0x1860 kernel/workqueue.c:2233 kthread+0x39c/0x470 kernel/kthread.c:231 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431 -> #2 ((&(&ifa->dad_work)->work)){+.+.}: process_one_work+0xba5/0x1be0 kernel/workqueue.c:2095 worker_thread+0x223/0x1860 kernel/workqueue.c:2233 kthread+0x39c/0x470 kernel/kthread.c:231 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431 0xffffffffffffffff -> #1 ((complete)&rcu.completion){+.+.}: check_prevs_add kernel/locking/lockdep.c:2020 [inline] validate_chain kernel/locking/lockdep.c:2469 [inline] __lock_acquire+0x3286/0x4620 kernel/locking/lockdep.c:3498 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4002 complete_acquire include/linux/completion.h:39 [inline] __wait_for_common kernel/sched/completion.c:108 [inline] wait_for_common kernel/sched/completion.c:122 [inline] wait_for_completion+0xc8/0x770 kernel/sched/completion.c:143 __synchronize_srcu+0x1b5/0x250 kernel/rcu/srcutree.c:898 synchronize_srcu_expedited kernel/rcu/srcutree.c:923 [inline] synchronize_srcu+0x1a3/0x560 kernel/rcu/srcutree.c:974 quarantine_remove_cache+0xd7/0xf0 mm/kasan/quarantine.c:327 kasan_cache_shrink+0x9/0x10 mm/kasan/kasan.c:380 kmem_cache_shrink+0x15/0x30 mm/slab_common.c:857 acpi_os_purge_cache+0x15/0x20 drivers/acpi/osl.c:1560 acpi_purge_cached_objects+0x38/0xc9 drivers/acpi/acpica/utxface.c:271 acpi_initialize_objects+0xc5/0x112 drivers/acpi/acpica/utxfinit.c:302 acpi_bus_init drivers/acpi/bus.c:1131 [inline] acpi_init+0x23c/0x8e6 drivers/acpi/bus.c:1220 do_one_initcall+0x9e/0x330 init/main.c:826 do_initcall_level init/main.c:892 [inline] do_initcalls init/main.c:900 [inline] do_basic_setup init/main.c:918 [inline] kernel_init_freeable+0x469/0x521 init/main.c:1066 kernel_init+0x13/0x172 init/main.c:993 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431 -> #0 (cpu_hotplug_lock.rw_sem){++++}: check_prev_add+0x865/0x1520 kernel/locking/lockdep.c:1894 check_prevs_add kernel/locking/lockdep.c:2020 [inline] validate_chain kernel/locking/lockdep.c:2469 [inline] __lock_acquire+0x3286/0x4620 kernel/locking/lockdep.c:3498 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4002 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:35 [inline] percpu_down_read include/linux/percpu-rwsem.h:58 [inline] cpus_read_lock+0x42/0x90 kernel/cpu.c:218 get_online_cpus include/linux/cpu.h:126 [inline] flush_all_backlogs net/core/dev.c:4592 [inline] rollback_registered_many+0x587/0xe80 net/core/dev.c:7127 rollback_registered+0x1be/0x3c0 net/core/dev.c:7183 unregister_netdevice_queue+0x2e3/0x5d0 net/core/dev.c:8171 unregister_netdevice include/linux/netdevice.h:2428 [inline] __tun_detach+0x1020/0x1390 drivers/net/tun.c:576 tun_detach drivers/net/tun.c:587 [inline] tun_chr_close+0x44/0x60 drivers/net/tun.c:2595 __fput+0x333/0x7f0 fs/file_table.c:210 ____fput+0x15/0x20 fs/file_table.c:246 task_work_run+0x199/0x270 kernel/task_work.c:112 exit_task_work include/linux/task_work.h:21 [inline] do_exit+0xa52/0x1b40 kernel/exit.c:865 do_group_exit+0x149/0x400 kernel/exit.c:968 get_signal+0x7e8/0x17e0 kernel/signal.c:2334 do_signal+0x94/0x1ee0 arch/x86/kernel/signal.c:808 exit_to_usermode_loop+0x224/0x300 arch/x86/entry/common.c:158 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath+0x42f/0x500 arch/x86/entry/common.c:266 entry_SYSCALL_64_fastpath+0xbc/0xbe other info that might help us debug this: Chain exists of: cpu_hotplug_lock.rw_sem --> (&(&ifa->dad_work)->work) --> rtnl_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(rtnl_mutex); lock((&(&ifa->dad_work)->work)); lock(rtnl_mutex); lock(cpu_hotplug_lock.rw_sem); *** DEADLOCK *** 1 lock held by syz-executor6/3924: #0: (rtnl_mutex){+.+.}, at: [] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:72 stack backtrace: CPU: 1 PID: 3924 Comm: syz-executor6 Not tainted 4.13.0-rc6-next-20170825+ #9 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:52 print_circular_bug+0x503/0x710 kernel/locking/lockdep.c:1259 check_prev_add+0x865/0x1520 kernel/locking/lockdep.c:1894 check_prevs_add kernel/locking/lockdep.c:2020 [inline] validate_chain kernel/locking/lockdep.c:2469 [inline] __lock_acquire+0x3286/0x4620 kernel/locking/lockdep.c:3498 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4002 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:35 [inline] percpu_down_read include/linux/percpu-rwsem.h:58 [inline] cpus_read_lock+0x42/0x90 kernel/cpu.c:218 get_online_cpus include/linux/cpu.h:126 [inline] flush_all_backlogs net/core/dev.c:4592 [inline] rollback_registered_many+0x587/0xe80 net/core/dev.c:7127 rollback_registered+0x1be/0x3c0 net/core/dev.c:7183 unregister_netdevice_queue+0x2e3/0x5d0 net/core/dev.c:8171 unregister_netdevice include/linux/netdevice.h:2428 [inline] __tun_detach+0x1020/0x1390 drivers/net/tun.c:576 tun_detach drivers/net/tun.c:587 [inline] tun_chr_close+0x44/0x60 drivers/net/tun.c:2595 __fput+0x333/0x7f0 fs/file_table.c:210 ____fput+0x15/0x20 fs/file_table.c:246 task_work_run+0x199/0x270 kernel/task_work.c:112 exit_task_work include/linux/task_work.h:21 [inline] do_exit+0xa52/0x1b40 kernel/exit.c:865 do_group_exit+0x149/0x400 kernel/exit.c:968 get_signal+0x7e8/0x17e0 kernel/signal.c:2334 do_signal+0x94/0x1ee0 arch/x86/kernel/signal.c:808 exit_to_usermode_loop+0x224/0x300 arch/x86/entry/common.c:158 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath+0x42f/0x500 arch/x86/entry/common.c:266 entry_SYSCALL_64_fastpath+0xbc/0xbe RIP: 0033:0x4512e9 RSP: 002b:00007f95b2e88cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 0000000000718218 RCX: 00000000004512e9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000718218 RBP: 00000000007181f8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000a6f7ef R14: 00007f95b2e899c0 R15: 0000000000000006 SELinux: unrecognized netlink message: protocol=9 nlmsg_type=64502 sclass=netlink_audit_socket pig=3937 comm=syz-executor4 SELinux: unrecognized netlink message: protocol=9 nlmsg_type=64502 sclass=netlink_audit_socket pig=3946 comm=syz-executor4 capability: warning: `syz-executor5' uses 32-bit capabilities (legacy support in use) netlink: 21 bytes leftover after parsing attributes in process `syz-executor3'. sctp: [Deprecated]: syz-executor7 (pid 4091) Use of int in maxseg socket option. Use struct sctp_assoc_value instead sctp: [Deprecated]: syz-executor7 (pid 4123) Use of int in maxseg socket option. Use struct sctp_assoc_value instead audit: type=1326 audit(1503860757.372:9): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=kernel pid=4180 comm="syz-executor5" exe="/root/syz-executor5" sig=31 arch=c000003e syscall=202 compat=0 ip=0x4512e9 code=0xffff0000 netlink: 21 bytes leftover after parsing attributes in process `syz-executor5'. audit: type=1326 audit(1503860757.488:10): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=kernel pid=4180 comm="syz-executor5" exe="/root/syz-executor5" sig=31 arch=c000003e syscall=202 compat=0 ip=0x4512e9 code=0xffff0000 sctp: [Deprecated]: syz-executor2 (pid 4329) Use of int in maxseg socket option. Use struct sctp_assoc_value instead device syz3 entered promiscuous mode netlink: 5 bytes leftover after parsing attributes in process `syz-executor1'. sctp: [Deprecated]: syz-executor2 (pid 4351) Use of int in maxseg socket option. Use struct sctp_assoc_value instead netlink: 5 bytes leftover after parsing attributes in process `syz-executor1'. SELinux: unrecognized netlink message: protocol=0 nlmsg_type=47638 sclass=netlink_route_socket pig=4379 comm=syz-executor2 netlink: 5 bytes leftover after parsing attributes in process `syz-executor4'. IPv6: NLM_F_REPLACE set, but no existing node found! netlink: 5 bytes leftover after parsing attributes in process `syz-executor4'. IPv6: NLM_F_REPLACE set, but no existing node found!