Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966159AbcCPIku (ORCPT ); Wed, 16 Mar 2016 04:40:50 -0400 Received: from mail.kernel.org ([198.145.29.136]:59331 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966022AbcCPIIU (ORCPT ); Wed, 16 Mar 2016 04:08:20 -0400 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Wengang Wang , Doug Ledford , Zefan Li Subject: [PATCH 3.4 022/107] rds: rds_ib_device.refcount overflow Date: Wed, 16 Mar 2016 16:05:16 +0800 Message-Id: <1458115601-5762-22-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1458115541-5712-1-git-send-email-lizf@kernel.org> References: <1458115541-5712-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1691 Lines: 54 From: Wengang Wang 3.4.111-rc1 review patch. If anyone has any objections, please let me know. ------------------ 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: Zefan Li --- 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 e8fdb17..a985158 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