On 07/12/2015 09:18 PM, Wengang Wang wrote: > Hi Doug, > > How do you think about this patch?
Sorry, I picked this up already. I must have missed sending out the
acknowledgment on this one.
> thanks,
> wengang
>
> 在 2015年07月06日 14:35, Wengang Wang 写道:
>> Fixes: 3e0249f9c05c ("RDS/IB: add refcount tracking to struct
>> rds_ib_device")
>>
>> 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]>
>> Reviewed-by: Haggai Eran <[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)
>
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--
Doug Ledford <[email protected]>
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