Hi Sean,
I run into the below ucma related warnings from the kernel with 3.3-rc5
when I stepped over crash of process as of wrong libs/etc (not the point
here...). Do you see here a real bug? basically the process was exiting
and the cleanup code in the kernel was running rdma_destroy_id when a
callback on that id was arriving from the IB CM. I saw that you lately
touched that/similar area in commit 9ced69ca5296567033804950d8d2161f454c5012
"RDMA/ucma: Discard all events for new connections until accepted"
Or.
======================================================
[ INFO: possible circular locking dependency detected ]
3.3.0-rc5-00008-g79f1e43-dirty #34 Tainted: G I
-------------------------------------------------------
tgtd/9018 is trying to acquire lock:
(&id_priv->handler_mutex){+.+.+.}, at: [<ffffffffa0359a41>]
rdma_destroy_id+0x33/0x1f0 [rdma_cm]
but task is already holding lock:
(&file->mut){+.+.+.}, at: [<ffffffffa02470fe>] ucma_free_ctx+0xb6/0x196
[rdma_ucm]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&file->mut){+.+.+.}:
[<ffffffff810682f3>] lock_acquire+0xf0/0x116
[<ffffffff8135f179>] mutex_lock_nested+0x64/0x2e6
[<ffffffffa0247636>] ucma_event_handler+0x148/0x1dc [rdma_ucm]
[<ffffffffa035a79a>] cma_ib_handler+0x1a7/0x1f7 [rdma_cm]
[<ffffffffa0333e88>] cm_process_work+0x32/0x119 [ib_cm]
[<ffffffffa03362ab>] cm_work_handler+0xfb8/0xfe5 [ib_cm]
[<ffffffff810423e2>] process_one_work+0x2bd/0x4a6
[<ffffffff810429e2>] worker_thread+0x1d6/0x350
[<ffffffff810462a6>] kthread+0x84/0x8c
[<ffffffff81369624>] kernel_thread_helper+0x4/0x10
-> #0 (&id_priv->handler_mutex){+.+.+.}:
[<ffffffff81067b86>] __lock_acquire+0x10d5/0x1752
[<ffffffff810682f3>] lock_acquire+0xf0/0x116
[<ffffffff8135f179>] mutex_lock_nested+0x64/0x2e6
[<ffffffffa0359a41>] rdma_destroy_id+0x33/0x1f0 [rdma_cm]
[<ffffffffa024715f>] ucma_free_ctx+0x117/0x196 [rdma_ucm]
[<ffffffffa0247255>] ucma_close+0x77/0xb4 [rdma_ucm]
[<ffffffff810df6ef>] fput+0x117/0x1cf
[<ffffffff810dc76e>] filp_close+0x6d/0x78
[<ffffffff8102b667>] put_files_struct+0xbd/0x17d
[<ffffffff8102b76d>] exit_files+0x46/0x4e
[<ffffffff8102d057>] do_exit+0x299/0x75d
[<ffffffff8102d599>] do_group_exit+0x7e/0xa9
[<ffffffff8103ae4b>] get_signal_to_deliver+0x536/0x555
[<ffffffff81001717>] do_signal+0x39/0x634
[<ffffffff81001d39>] do_notify_resume+0x27/0x69
[<ffffffff81361c03>] retint_signal+0x46/0x83
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&file->mut);
lock(&id_priv->handler_mutex);
lock(&file->mut);
lock(&id_priv->handler_mutex);
*** DEADLOCK ***
1 lock held by tgtd/9018:
#0: (&file->mut){+.+.+.}, at: [<ffffffffa02470fe>] ucma_free_ctx+0xb6/0x196
[rdma_ucm]
stack backtrace:
Pid: 9018, comm: tgtd Tainted: G I 3.3.0-rc5-00008-g79f1e43-dirty #34
Call Trace:
[<ffffffff81029e9c>] ? console_unlock+0x18e/0x207
[<ffffffff81066433>] print_circular_bug+0x28e/0x29f
[<ffffffff81067b86>] __lock_acquire+0x10d5/0x1752
[<ffffffff810682f3>] lock_acquire+0xf0/0x116
[<ffffffffa0359a41>] ? rdma_destroy_id+0x33/0x1f0 [rdma_cm]
[<ffffffff8135f179>] mutex_lock_nested+0x64/0x2e6
[<ffffffffa0359a41>] ? rdma_destroy_id+0x33/0x1f0 [rdma_cm]
[<ffffffff8106546d>] ? trace_hardirqs_on_caller+0x11e/0x155
[<ffffffff810654b1>] ? trace_hardirqs_on+0xd/0xf
[<ffffffffa0359a41>] rdma_destroy_id+0x33/0x1f0 [rdma_cm]
[<ffffffffa024715f>] ucma_free_ctx+0x117/0x196 [rdma_ucm]
[<ffffffffa0247255>] ucma_close+0x77/0xb4 [rdma_ucm]
[<ffffffff810df6ef>] fput+0x117/0x1cf
[<ffffffff810dc76e>] filp_close+0x6d/0x78
[<ffffffff8102b667>] put_files_struct+0xbd/0x17d
[<ffffffff8102b5cc>] ? put_files_struct+0x22/0x17d
[<ffffffff8102b76d>] exit_files+0x46/0x4e
[<ffffffff8102d057>] do_exit+0x299/0x75d
[<ffffffff8102d599>] do_group_exit+0x7e/0xa9
[<ffffffff8103ae4b>] get_signal_to_deliver+0x536/0x555
[<ffffffff810654b1>] ? trace_hardirqs_on+0xd/0xf
[<ffffffff81001717>] do_signal+0x39/0x634
[<ffffffff8135e037>] ? printk+0x3c/0x45
[<ffffffff8106546d>] ? trace_hardirqs_on_caller+0x11e/0x155
[<ffffffff810654b1>] ? trace_hardirqs_on+0xd/0xf
[<ffffffff81361803>] ? _raw_spin_unlock_irq+0x2b/0x40
[<ffffffff81039011>] ? set_current_blocked+0x44/0x49
[<ffffffff81361bce>] ? retint_signal+0x11/0x83
[<ffffffff81001d39>] do_notify_resume+0x27/0x69
[<ffffffff8118a1fe>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[<ffffffff81361c03>] retint_signal+0x46/0x83
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