From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:48624 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753955AbbH0Psl (ORCPT ); Thu, 27 Aug 2015 11:48:41 -0400 From: Sasha Levin To: stable@vger.kernel.org, stable-commits@vger.kernel.org Cc: Wengang Wang , Doug Ledford , Sasha Levin Subject: [added to the 3.18 stable tree] rds: rds_ib_device.refcount overflow Date: Thu, 27 Aug 2015 11:38:30 -0400 Message-Id: <1440689954-10813-72-git-send-email-sasha.levin@oracle.com> In-Reply-To: <1440689954-10813-1-git-send-email-sasha.levin@oracle.com> References: <1440689954-10813-1-git-send-email-sasha.levin@oracle.com> Sender: stable-owner@vger.kernel.org List-ID: From: Wengang Wang This patch has been added to the 3.18 stable tree. If you have any objections, please let us know. =============== [ Upstream commit 4fabb59449aa44a585b3603ffdadd4c5f4d0c033 ] 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 Reviewed-by: Haggai Eran Signed-off-by: Doug Ledford Signed-off-by: Sasha Levin --- 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) -- 2.1.4