This appears to be this bug: https://bugzilla.redhat.com/show_bug.cgi?id=734519 Test case was to create 40 (virtual) stations against an AP that can only handle 30, so the remaining 10 constantly try to re-associate, get DHCP if they manage, etc.... cfg80211: Calling CRDA for country: US ====================================================== [ INFO: possible circular locking dependency detected ] 3.3.6+ #1 Tainted: G WC O ------------------------------------------------------- kworker/1:2/62 is trying to acquire lock: (cfg80211_mutex){+.+.+.}, at: [<ffffffffa00f7ced>] restore_regulatory_settings+0x2c/0x4af [cfg80211] but task is already holding lock: ((reg_timeout).work){+.+...}, at: [<ffffffff8104c5c1>] process_one_work+0x1c2/0x35a which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 ((reg_timeout).work){+.+...}: [<ffffffff810799bb>] lock_acquire+0x64/0x81 [<ffffffff8104e038>] wait_on_work+0x54/0xd3 [<ffffffff8104e196>] __cancel_work_timer+0xdf/0x128 [<ffffffff8104e1ec>] cancel_delayed_work_sync+0xd/0xf [<ffffffffa00f81f5>] reg_set_request_processed+0x4c/0x66 [cfg80211] [<ffffffffa00f9675>] set_regdom+0x5f8/0x69f [cfg80211] [<ffffffffa01069ab>] nl80211_set_reg+0x213/0x26c [cfg80211] [<ffffffff813da541>] genl_rcv_msg+0x1f4/0x239 [<ffffffff813d921d>] netlink_rcv_skb+0x3e/0x8f [<ffffffff813da346>] genl_rcv+0x21/0x28 [<ffffffff813d8ff8>] netlink_unicast+0xe9/0x152 [<ffffffff813d9777>] netlink_sendmsg+0x1f8/0x216 [<ffffffff813a5d3d>] __sock_sendmsg_nosec+0x5f/0x6a [<ffffffff813a5d85>] __sock_sendmsg+0x3d/0x48 [<ffffffff813a662f>] sock_sendmsg+0xa3/0xbc [<ffffffff813a6e38>] __sys_sendmsg+0x20f/0x29c [<ffffffff813a702e>] sys_sendmsg+0x3d/0x5b [<ffffffff8147cd79>] system_call_fastpath+0x16/0x1b -> #1 (reg_mutex){+.+.+.}: [<ffffffff810799bb>] lock_acquire+0x64/0x81 [<ffffffff81475319>] __mutex_lock_common+0x64/0x4b5 [<ffffffff81475851>] mutex_lock_nested+0x36/0x3b [<ffffffffa00f8bd3>] reg_todo+0x2d/0x4d7 [cfg80211] [<ffffffff8104c622>] process_one_work+0x223/0x35a [<ffffffff8104eac5>] worker_thread+0x136/0x255 [<ffffffff810526be>] kthread+0x84/0x8c [<ffffffff8147e1b4>] kernel_thread_helper+0x4/0x10 -> #0 (cfg80211_mutex){+.+.+.}: [<ffffffff81079667>] __lock_acquire+0xade/0xdce [<ffffffff810799bb>] lock_acquire+0x64/0x81 [<ffffffff81475319>] __mutex_lock_common+0x64/0x4b5 [<ffffffff81475851>] mutex_lock_nested+0x36/0x3b [<ffffffffa00f7ced>] restore_regulatory_settings+0x2c/0x4af [cfg80211] [<ffffffffa00f818c>] reg_timeout_work+0x1c/0x1e [cfg80211] [<ffffffff8104c622>] process_one_work+0x223/0x35a [<ffffffff8104eac5>] worker_thread+0x136/0x255 [<ffffffff810526be>] kthread+0x84/0x8c [<ffffffff8147e1b4>] kernel_thread_helper+0x4/0x10 other info that might help us debug this: Chain exists of: cfg80211_mutex --> reg_mutex --> (reg_timeout).work Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((reg_timeout).work); lock(reg_mutex); lock((reg_timeout).work); lock(cfg80211_mutex); *** DEADLOCK *** 2 locks held by kworker/1:2/62: #0: (events){.+.+.+}, at: [<ffffffff8104c5c1>] process_one_work+0x1c2/0x35a #1: ((reg_timeout).work){+.+...}, at: [<ffffffff8104c5c1>] process_one_work+0x1c2/0x35a stack backtrace: Pid: 62, comm: kworker/1:2 Tainted: G WC O 3.3.6+ #1 Call Trace: [<ffffffff810779a6>] print_circular_bug+0x1ff/0x210 [<ffffffff81079667>] __lock_acquire+0xade/0xdce [<ffffffff8105c5e0>] ? get_parent_ip+0x11/0x42 [<ffffffff810799bb>] lock_acquire+0x64/0x81 [<ffffffffa00f7ced>] ? restore_regulatory_settings+0x2c/0x4af [cfg80211] [<ffffffff8147af6a>] ? add_preempt_count+0xad/0xb1 [<ffffffff81475319>] __mutex_lock_common+0x64/0x4b5 [<ffffffffa00f7ced>] ? restore_regulatory_settings+0x2c/0x4af [cfg80211] [<ffffffff81078905>] ? trace_hardirqs_on+0xd/0xf [<ffffffffa00f7ced>] ? restore_regulatory_settings+0x2c/0x4af [cfg80211] [<ffffffff81475851>] mutex_lock_nested+0x36/0x3b [<ffffffffa00f7ced>] restore_regulatory_settings+0x2c/0x4af [cfg80211] [<ffffffffa00f818c>] reg_timeout_work+0x1c/0x1e [cfg80211] [<ffffffff8104c622>] process_one_work+0x223/0x35a [<ffffffff8104c5c1>] ? process_one_work+0x1c2/0x35a [<ffffffffa00f8170>] ? restore_regulatory_settings+0x4af/0x4af [cfg80211] [<ffffffff8104eac5>] worker_thread+0x136/0x255 [<ffffffff8104e98f>] ? manage_workers+0x191/0x191 [<ffffffff810526be>] kthread+0x84/0x8c [<ffffffff8147e1b4>] kernel_thread_helper+0x4/0x10 [<ffffffff81477fb8>] ? retint_restore_args+0x13/0x13 [<ffffffff8105263a>] ? __init_kthread_worker+0x56/0x56 [<ffffffff8147e1b0>] ? gs_change+0x13/0x13 cfg80211: Restoring regulatory settings including user preference Thanks, Ben -- Ben Greear <greearb@xxxxxxxxxxxxxxx> Candela Technologies Inc http://www.candelatech.com -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
