Commits
Sean Hefty committed b6cec8aa4a7
RDMA/cma: Fix lockdep false positive recursive locking
The following lockdep problem was reported by Or Gerlitz <ogerlitz@mellanox.com>:
[ INFO: possible recursive locking detected ]
3.3.0-32035-g1b2649e-dirty #4 Not tainted
---------------------------------------------
kworker/5:1/418 is trying to acquire lock:
(&id_priv->handler_mutex){+.+.+.}, at: [<ffffffffa0138a41>] rdma_destroy_i d+0x33/0x1f0 [rdma_cm]
but task is already holding lock:
(&id_priv->handler_mutex){+.+.+.}, at: [<ffffffffa0135130>] cma_disable_ca llback+0x24/0x45 [rdma_cm]
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&id_priv->handler_mutex);
lock(&id_priv->handler_mutex);
*** DEADLOCK ***
May be due to missing lock nesting notation
3 locks held by kworker/5:1/418:
#0: (ib_cm){.+.+.+}, at: [<ffffffff81042ac1>] process_one_work+0x210/0x4a 6
#1: ((&(&work->work)->work)){+.+.+.}, at: [<ffffffff81042ac1>] process_on e_work+0x210/0x4a6
#2: (&id_priv->handler_mutex){+.+.+.}, at: [<ffffffffa0135130>] cma_disab le_callback+0x24/0x45 [rdma_cm]
stack backtrace:
Pid: 418, comm: kworker/5:1 Not tainted 3.3.0-32035-g1b2649e-dirty #4
Call Trace:
[<ffffffff8102b0fb>] ? console_unlock+0x1f4/0x204
[<ffffffff81068771>] __lock_acquire+0x16b5/0x174e
[<ffffffff8106461f>] ? save_trace+0x3f/0xb3
[<ffffffff810688fa>] lock_acquire+0xf0/0x116
[<ffffffffa0138a41>] ? rdma_destroy_id+0x33/0x1f0 [rdma_cm]
[<ffffffff81364351>] mutex_lock_nested+0x64/0x2ce
[<ffffffffa0138a41>] ? rdma_destroy_id+0x33/0x1f0 [rdma_cm]
[<ffffffff81065a78>] ? trace_hardirqs_on_caller+0x11e/0x155
[<ffffffff81065abc>] ? trace_hardirqs_on+0xd/0xf
[<ffffffffa0138a41>] rdma_destroy_id+0x33/0x1f0 [rdma_cm]
[<ffffffffa0139c02>] cma_req_handler+0x418/0x644 [rdma_cm]
[<ffffffffa012ee88>] cm_process_work+0x32/0x119 [ib_cm]
[<ffffffffa0130299>] cm_req_handler+0x928/0x982 [ib_cm]
[<ffffffffa01302f3>] ? cm_req_handler+0x982/0x982 [ib_cm]
[<ffffffffa0130326>] cm_work_handler+0x33/0xfe5 [ib_cm]
[<ffffffff81065a78>] ? trace_hardirqs_on_caller+0x11e/0x155
[<ffffffffa01302f3>] ? cm_req_handler+0x982/0x982 [ib_cm]
[<ffffffff81042b6e>] process_one_work+0x2bd/0x4a6
[<ffffffff81042ac1>] ? process_one_work+0x210/0x4a6
[<ffffffff813669f3>] ? _raw_spin_unlock_irq+0x2b/0x40
[<ffffffff8104316e>] worker_thread+0x1d6/0x350
[<ffffffff81042f98>] ? rescuer_thread+0x241/0x241
[<ffffffff81046a32>] kthread+0x84/0x8c
[<ffffffff8136e854>] kernel_thread_helper+0x4/0x10
[<ffffffff81366d59>] ? retint_restore_args+0xe/0xe
[<ffffffff810469ae>] ? __init_kthread_worker+0x56/0x56
[<ffffffff8136e850>] ? gs_change+0xb/0xb
The actual locking is fine, since we're dealing with different locks,
but from the same lock class. cma_disable_callback() acquires the
listening id mutex, whereas rdma_destroy_id() acquires the mutex for
the new connection id. To fix this, delay the call to
rdma_destroy_id() until we've released the listening id mutex.
Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>