From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754585AbbHEVwh (ORCPT ); Wed, 5 Aug 2015 17:52:37 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:38863 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753810AbbHEVuv (ORCPT ); Wed, 5 Aug 2015 17:50:51 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Wengang Wang , Doug Ledford , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 107/107] rds: rds_ib_device.refcount overflow Date: Wed, 5 Aug 2015 14:49:39 -0700 Message-Id: <1438811379-384-108-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1438811379-384-1-git-send-email-kamal@canonical.com> References: <1438811379-384-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.19.8-ckt5 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Wengang Wang 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 Reviewed-by: Haggai Eran Signed-off-by: Doug Ledford Signed-off-by: Kamal Mostafa --- 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) -- 1.9.1