On 24/06/2015 07:54, Wengang Wang wrote:
> There lacks a dropping on rds_ib_device.refcount in case rds_ib_alloc_fmr
> failed(mr pool running out). this lead to the refcount overflow.
>
> A complain in line 117(see following) is seen. From vmcore:
> s_ib_rdma_mr_pool_depleted is 2147485544 and rds_ibdev->refcount is
> -2147475448.
> That is the evidence the mr pool is used up. so rds_ib_alloc_fmr is very
> likely
> to return ERR_PTR(-EAGAIN).
>
> 115 void rds_ib_dev_put(struct rds_ib_device *rds_ibdev)
> 116 {
> 117 BUG_ON(atomic_read(&rds_ibdev->refcount) <= 0);
> 118 if (atomic_dec_and_test(&rds_ibdev->refcount))
> 119 queue_work(rds_wq, &rds_ibdev->free_work);
> 120 }
>
> fix is to drop refcount when rds_ib_alloc_fmr failed.
>
> Signed-off-by: Wengang Wang <[email protected]>
> ---
> net/rds/ib_rdma.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/net/rds/ib_rdma.c b/net/rds/ib_rdma.c
> index 273b8bf..657ba9f 100644
> --- a/net/rds/ib_rdma.c
> +++ b/net/rds/ib_rdma.c
> @@ -759,8 +759,10 @@ void *rds_ib_get_mr(struct scatterlist *sg, unsigned
> long nents,
> }
>
> ibmr = rds_ib_alloc_fmr(rds_ibdev);
> - if (IS_ERR(ibmr))
> + if (IS_ERR(ibmr)) {
> + rds_ib_dev_put(rds_ibdev);
> return ibmr;
> + }
>
> ret = rds_ib_map_fmr(rds_ibdev, ibmr, sg, nents);
> if (ret == 0)
>
It seems like the function indeed is missing a put on the rds_ibdev in
that case.
Reviewed-by: Haggai Eran <[email protected]>
You may also want to add:
Fixes: 3e0249f9c05c ("RDS/IB: add refcount tracking to struct
rds_ib_device")
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