diff mbox

[3.16.y-ckt,068/118] rds: rds_ib_device.refcount overflow

Message ID 1439369820-27005-69-git-send-email-luis.henriques@canonical.com
State New
Headers show

Commit Message

Luis Henriques Aug. 12, 2015, 8:56 a.m. UTC 
3.16.7-ckt16 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Wengang Wang <wen.gang.wang@oracle.com>

commit 4fabb59449aa44a585b3603ffdadd4c5f4d0c033 upstream.

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 <wen.gang.wang@oracle.com>
Reviewed-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 net/rds/ib_rdma.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
diff mbox

Patch

diff --git a/net/rds/ib_rdma.c b/net/rds/ib_rdma.c
index e8fdb172adbb..a985158d95d5 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)