====================================================== WARNING: possible circular locking dependency detected 4.13.0-rc6-next-20170825+ #9 Not tainted ------------------------------------------------------ syz-executor7/3508 is trying to acquire lock: (cpu_hotplug_lock.rw_sem){++++}, at: [] static_key_slow_inc+0x9d/0x3c0 kernel/jump_label.c:123 but task is already holding lock: (rtnl_mutex){+.+.}, at: [] rtnl_lock net/core/rtnetlink.c:72 [inline] (rtnl_mutex){+.+.}, at: [] rtnetlink_rcv_msg+0x65c/0x1090 net/core/rtnetlink.c:4241 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 static_key_slow_inc+0x9d/0x3c0 kernel/jump_label.c:123 ip_tunnel_need_metadata+0x15/0x20 net/ipv4/ip_tunnel_core.c:431 fib_nl_newrule+0x192f/0x2b80 net/core/fib_rules.c:610 rtnetlink_rcv_msg+0x733/0x1090 net/core/rtnetlink.c:4246 netlink_rcv_skb+0x216/0x440 net/netlink/af_netlink.c:2397 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4258 netlink_unicast_kernel net/netlink/af_netlink.c:1265 [inline] netlink_unicast+0x4e8/0x6f0 net/netlink/af_netlink.c:1291 netlink_sendmsg+0xa4a/0xe70 net/netlink/af_netlink.c:1854 sock_sendmsg_nosec net/socket.c:633 [inline] sock_sendmsg+0xca/0x110 net/socket.c:643 sock_write_iter+0x320/0x5e0 net/socket.c:912 call_write_iter include/linux/fs.h:1744 [inline] do_iter_readv_writev+0x531/0x7f0 fs/read_write.c:650 do_iter_write+0x15a/0x540 fs/read_write.c:929 vfs_writev+0x18a/0x340 fs/read_write.c:975 do_writev+0xfc/0x2a0 fs/read_write.c:1011 SYSC_writev fs/read_write.c:1084 [inline] SyS_writev+0x27/0x30 fs/read_write.c:1081 entry_SYSCALL_64_fastpath+0x1f/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-executor7/3508: #0: (rtnl_mutex){+.+.}, at: [] rtnl_lock net/core/rtnetlink.c:72 [inline] #0: (rtnl_mutex){+.+.}, at: [] rtnetlink_rcv_msg+0x65c/0x1090 net/core/rtnetlink.c:4241 stack backtrace: CPU: 0 PID: 3508 Comm: syz-executor7 Not tainted 4.13.0-rc6-next-20170825+ #9 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 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 static_key_slow_inc+0x9d/0x3c0 kernel/jump_label.c:123 ip_tunnel_need_metadata+0x15/0x20 net/ipv4/ip_tunnel_core.c:431 fib_nl_newrule+0x192f/0x2b80 net/core/fib_rules.c:610 rtnetlink_rcv_msg+0x733/0x1090 net/core/rtnetlink.c:4246 netlink_rcv_skb+0x216/0x440 net/netlink/af_netlink.c:2397 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4258 netlink_unicast_kernel net/netlink/af_netlink.c:1265 [inline] netlink_unicast+0x4e8/0x6f0 net/netlink/af_netlink.c:1291 netlink_sendmsg+0xa4a/0xe70 net/netlink/af_netlink.c:1854 sock_sendmsg_nosec net/socket.c:633 [inline] sock_sendmsg+0xca/0x110 net/socket.c:643 sock_write_iter+0x320/0x5e0 net/socket.c:912 call_write_iter include/linux/fs.h:1744 [inline] do_iter_readv_writev+0x531/0x7f0 fs/read_write.c:650 do_iter_write+0x15a/0x540 fs/read_write.c:929 vfs_writev+0x18a/0x340 fs/read_write.c:975 do_writev+0xfc/0x2a0 fs/read_write.c:1011 SYSC_writev fs/read_write.c:1084 [inline] SyS_writev+0x27/0x30 fs/read_write.c:1081 entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x446749 RSP: 002b:00007fdd5d17dc08 EFLAGS: 00000296 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 000000000000001a RCX: 0000000000446749 RDX: 0000000000000001 RSI: 0000000020917ff0 RDI: 000000000000001a RBP: 0000000000000086 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000296 R12: 00000000ffffffff R13: 00000000000057d0 R14: 00000000006e7890 R15: 0000000000000000 netlink: 1 bytes leftover after parsing attributes in process `syz-executor7'. netlink: 1 bytes leftover after parsing attributes in process `syz-executor7'. TCP: request_sock_TCPv6: Possible SYN flooding on port 20013. Sending cookies. Check SNMP counters. netlink: 1 bytes leftover after parsing attributes in process `syz-executor7'. netlink: 11 bytes leftover after parsing attributes in process `syz-executor3'. netlink: 11 bytes leftover after parsing attributes in process `syz-executor3'. semctl(GETNCNT/GETZCNT) is since 3.16 Single Unix Specification compliant. The task syz-executor2 (3629) triggered the difference, watch for misbehavior.