linux-kernel - Re: [PATCH for-next] RDMA/cm: Rate limit destroy CM ID timeout error message

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Message-ID: <20251015184516.GK3938986@ziepe.ca>
Date: Wed, 15 Oct 2025 15:45:16 -0300
From: Jason Gunthorpe <jgg@...pe.ca>
To: Sean Hefty <shefty@...dia.com>
Cc: Haakon Bugge <haakon.bugge@...cle.com>,
	Jacob Moroni <jmoroni@...gle.com>,
	Leon Romanovsky <leon@...nel.org>,
	Vlad Dumitrescu <vdumitrescu@...dia.com>,
	Or Har-Toov <ohartoov@...dia.com>,
	Manjunath Patil <manjunath.b.patil@...cle.com>,
	OFED mailing list <linux-rdma@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH for-next] RDMA/cm: Rate limit destroy CM ID timeout error
 message

On Wed, Oct 15, 2025 at 06:34:33PM +0000, Sean Hefty wrote:
> > > With this hack, running cmtime with 10.000 connections in loopback,
> > > the "cm_destroy_id_wait_timeout: cm_id=000000007ce44ace timed out.
> > > state 6 -> 0, refcnt=1" messages are indeed produced. Had to kill
> > > cmtime because it was hanging, and then it got defunct with the
> > > following stack:
> > 
> > Seems like a bug, it should not hang forever if a MAD is lost..
> 
> The hack skipped calling ib_post_send.  But the result of that is a
> completion is never written to the CQ.  The state machine or
> reference counting is likely waiting for the completion, so it knows
> that HW is done trying to access the buffer.

That does make sense, it has to immediately trigger the completion to
be accurate. A better test would be to truncate the mad or something
so it can't be rx'd

Jason