From: Jason Gunthorpe <jgg@nvidia.com>
To: Bob Pearson <rpearsonhpe@gmail.com>
Cc: zyjzyj2000@gmail.com, linux-rdma@vger.kernel.org
Subject: Re: [PATCH for-next v12 6/6] RDMA/rxe: Convert mca read locking to RCU
Date: Wed, 23 Feb 2022 20:04:46 -0400 [thread overview]
Message-ID: <20220224000446.GA409228@nvidia.com> (raw)
In-Reply-To: <34b05c41-c674-7120-8d0c-0ceedab50b50@gmail.com>
On Wed, Feb 23, 2022 at 04:40:19PM -0600, Bob Pearson wrote:
> OK I looked at this again. Here is what happens.
>
> without the complete()/wait_for_completion() fix the test passes but
> the (private i.e. not visible to rdma-core) mca object is holding a
> reference on qp which will be freed after the call_rcu() subroutine
> takes place. Meanwhile the ib_detach_mcast() call returns to
> rdma-core and since there is nothing left to do the test is over and
> the python code closes the device. But this generates a warning
> (rdma_core.c line 940) since not all the user objects (i.e. the qp)
> were freed. In other contexts we are planning on putting
> complete()/wait...()'s in all the other verbs calls which ref count
> objects for the same reason. I think it applies here too.
This explanation makes sense..
The mistake is on the QP side where it has a refcount but doesn't wait
for it to drain I suppose.
Jason
prev parent reply other threads:[~2022-02-24 0:04 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-18 0:35 [PATCH for-next v12 0/6] Move two object pools to rxe_mcast.c Bob Pearson
2022-02-18 0:35 ` [PATCH for-next v12 1/6] RDMA/rxe: Add code to cleanup mcast memory Bob Pearson
2022-02-23 19:33 ` Jason Gunthorpe
2022-02-18 0:35 ` [PATCH for-next v12 2/6] RDMA/rxe: Collect mca init code in a subroutine Bob Pearson
2022-02-18 0:35 ` [PATCH for-next v12 3/6] RDMA/rxe: Collect cleanup mca " Bob Pearson
2022-02-18 0:35 ` [PATCH for-next v12 4/6] RDMA/rxe: Cleanup rxe_mcast.c Bob Pearson
2022-02-18 0:35 ` [PATCH for-next v12 5/6] RDMA/rxe: For mcast copy qp list to temp array Bob Pearson
2022-02-18 0:35 ` [PATCH for-next v12 6/6] RDMA/rxe: Convert mca read locking to RCU Bob Pearson
2022-02-23 19:52 ` Jason Gunthorpe
2022-02-23 22:40 ` Bob Pearson
2022-02-24 0:04 ` Jason Gunthorpe [this message]
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