From: Wengang Wang Date: Tue, 4 Aug 2015 05:39:51 +0000 (+0800) Subject: rds: rds_ib_device.refcount overflow X-Git-Tag: v4.1.12-92~293^2^2~2 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=e1ba562f67fc2013847e64c8659f7f96b344b7db;p=users%2Fjedix%2Flinux-maple.git rds: rds_ib_device.refcount overflow Fixes: 3e0249f9c05c ("RDS/IB: add refcount tracking to struct rds_ib_device") There is a missing dropping of refcount on rds_ib_device.refcount in case rds_ib_alloc_fmr() failed(mr pool running out). This lead to the refcount overflow. A BUG_ON on line 117(see following) is triggered. 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 } The fix is to drop refcount when rds_ib_alloc_fmr() failed. upstream commit: 4fabb59449aa44a585b3603ffdadd4c5f4d0c033 Orabug: 21534438 Signed-off-by: Wengang Wang Reviewed-by: Haggai Eran Signed-off-by: Doug Ledford Acked-by: Wei Xu Acked-by: Zheng Li Signed-off-by: Guangyu Sun --- diff --git a/net/rds/ib_rdma.c b/net/rds/ib_rdma.c index 03cb6c91aa154..426d64366d484 100644 --- a/net/rds/ib_rdma.c +++ b/net/rds/ib_rdma.c @@ -875,8 +875,10 @@ void *rds_ib_get_mr(struct scatterlist *sg, unsigned long nents, } ibmr = rds_ib_alloc_fmr(rds_ibdev, nents); - 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)