Re: [PATCH rdma-next] RDMA/mana_ib: drain QP references after partial table insertion

[Leon Romanovsky <leon@kernel.org>]

On Wed, Jul 22, 2026 at 09:18:12AM +0000, Konstantin Taranov wrote:
> > From: Leon Romanovsky <leonro@nvidia.com>
> > 
> > mana_table_store_ud_qp() publishes a QP at its send-queue id before
> > inserting the receive-queue id, dropping the XArray lock between the two
> > xa_insert_irq() calls. A concurrent completion handler can look up the QP and
> > take a transient reference. When the second insertion fails, the rollback
> > erased only the send-queue entry and returned, leaving both the initial table
> > reference and the transient reference outstanding while RDMA core frees the
> > QP, causing a use-after-free.
> > 
> > Drain the reference as normal destruction does: drop the initial reference and
> > wait for qp->free, releasing the QP only after every concurrent lookup returns
> > its reference.
> > 
> > Fixes: 8001e9257eca ("RDMA/mana_ib: extend mana QP table")
> > Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> 
> Reviewed-by: Konstantin Taranov <kotaranov@microsoft.com> 
> 
> > ---
> > Konstantin,
> > 
> > I saw this in one of the Sashiko runs, and I believe the AI is correct. The
> > reference can be acquired through the GDMA_EQE_RNIC_QP_FATAL event.
> > 
> 
> I doubt that it is possible for EQEs. The eqe only can mention an RQ and we first try to insert an SQ.
> As well as when we drain GSI QP, we also look up with an RQ.

GDMA_EQE_RNIC_QP_FATAL is my interpretation, and not AI :).

Thanks