From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22559C77B73 for ; Mon, 17 Apr 2023 03:10:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230055AbjDQDKU (ORCPT ); Sun, 16 Apr 2023 23:10:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34584 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230315AbjDQDJ0 (ORCPT ); Sun, 16 Apr 2023 23:09:26 -0400 Received: from out-34.mta1.migadu.com (out-34.mta1.migadu.com [IPv6:2001:41d0:203:375::22]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A1825B6 for ; Sun, 16 Apr 2023 20:08:43 -0700 (PDT) Message-ID: <90bcf57d-3e2f-5fd5-a901-6a640d2b523c@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1681700892; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=c/5MImZBx71ArdVTD8JIk3uIrjgFKB62VcP4IolAfhg=; b=tNx2slIOxnlY6tArRUlKKGAGc3DcI6ueTMOywqot4Icxtxm6c3iKDi/TJVUgsB/KktrZux aEGe7miRueNqkMQmDgXAm7iV8zSxW+QPotvQ0yvsDXLGk6sdATTyFlEaFLJpXrhBwaODSm 6zeAndOGbQgVMzKRv+F87+YFjA20JHU= Date: Mon, 17 Apr 2023 11:08:09 +0800 MIME-Version: 1.0 Subject: Re: [PATCH for-next 2/3] RDMA/rtrs: Fix rxe_dealloc_pd warning To: "Zhijian Li (Fujitsu)" , Leon Romanovsky Cc: "haris.iqbal@ionos.com" , "jinpu.wang@ionos.com" , "jgg@ziepe.ca" , "linux-rdma@vger.kernel.org" , "linux-kernel@vger.kernel.org" References: <1681108984-2-1-git-send-email-lizhijian@fujitsu.com> <1681108984-2-3-git-send-email-lizhijian@fujitsu.com> <20230410120809.GN182481@unreal> <0d9c57db-bca3-adb4-71fd-7362e4842917@linux.dev> <85323eb2-cfc7-d1b8-3a75-3fa63dde29db@fujitsu.com> <20230411122651.GV182481@unreal> <8fe62e38-e43d-3d6c-624f-1c8ce5859788@linux.dev> <230b310a-26ef-34f1-4c3b-c2360088ce04@linux.dev> <71935de6-e3c1-c719-4e66-19242af51ab7@fujitsu.com> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Guoqing Jiang In-Reply-To: <71935de6-e3c1-c719-4e66-19242af51ab7@fujitsu.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/14/23 18:09, Zhijian Li (Fujitsu) wrote: > > On 14/04/2023 14:04, Guoqing Jiang wrote: >> >> On 4/14/23 13:37, Zhijian Li (Fujitsu) wrote: >>> On 14/04/2023 11:40, Guoqing Jiang wrote: >>>> On 4/13/23 16:12, Zhijian Li (Fujitsu) wrote: >>>>> On 13/04/2023 15:35, Guoqing Jiang wrote: >>>>>> Hi, >>>>>> >>>>>> I take a closer look today. >>>>>> >>>>>> On 4/12/23 09:15, Zhijian Li (Fujitsu) wrote: >>>>>>> On 11/04/2023 20:26, Leon Romanovsky wrote: >>>>>>>> On Tue, Apr 11, 2023 at 02:43:46AM +0000, Zhijian Li (Fujitsu) wrote: >>>>>>>>> On 10/04/2023 21:10, Guoqing Jiang wrote: >>>>>>>>>> On 4/10/23 20:08, Leon Romanovsky wrote: >>>>>>>>>>> On Mon, Apr 10, 2023 at 06:43:03AM +0000, Li Zhijian wrote: >>>>>>>>>>>> The warning occurs when destroying PD whose reference count is not zero. >>>>>>>>>>>> >>>>>>>>>>>> Precodition: clt_path->s.con_num is 2. >>>>>>>>>>>> So 2 cm connection will be created as below: >>>>>>>>>>>> CPU0                                              CPU1 >>>>>>>>>>>> init_conns {                              | >>>>>>>>>>>>        create_cm() // a. con[0] created        | >>>>>>>>>>>>                                                |  a'. rtrs_clt_rdma_cm_handler() { >>>>>>>>>>>>                                                |    rtrs_rdma_addr_resolved() >>>>>>>>>>>>                                                |      create_con_cq_qp(con); << con[0] >>>>>>>>>>>>                                                |  } >>>>>>>>>>>>                                                | in this moment, refcnt of PD was increased to 2+ >>>>>> What do you mean "refcnt of PD"? usecnt in struct ib_pd or dev_ref. >>>>> I mean usecnt in struct ib_pd >>>>> >>>>>>>>>>>>                                                | >>>>>>>>>>>>        create_cm() // b. cid = 1, failed       | >>>>>>>>>>>>          destroy_con_cq_qp()                   | >>>>>>>>>>>>            rtrs_ib_dev_put()                   | >>>>>>>>>>>>              dev_free()                        | >>>>>>>>>>>>                ib_dealloc_pd(dev->ib_pd) << PD | >>>>>>>>>>>>                 is destroyed, but refcnt is    | >>>>>>>>>>>>                 still greater than 0           | >>>>>> Assuming you mean "pd->usecnt". We only allocate pd in con[0] by rtrs_ib_dev_find_or_add, >>>>>> if con[1] failed to create cm, then alloc_path_reqs -> ib_alloc_mr -> atomic_inc(&pd->usecnt) >>>> The above can't be invoked, right? >>>> >>>>>> can't be triggered. Is there other places could increase the refcnt? >>>>> Yes, when create a qp, it will also associate to this PD, that also mean refcnt of PD will be increased. >>>>> >>>>> When con[0](create_con_cq_qp) succeeded, refcnt of PD will be 2. and then when con[1] failed, since >>>>> QP didn't create, refcnt of PD is still 2. con[1]'s cleanup will destroy the PD(ib_dealloc_pd) since dev_ref = 1, after that its >>>>> refcnt is still 1. >>>> I can see the path increase usecnt to 1. >>>> >>>> rtrs_cq_qp_create -> create_qp >>>>                       -> rdma_create_qp >>>>                           -> ib_create_qp >>>>                               -> create_qp >>>>                               -> ib_qp_usecnt_inc which increases pd->usecnt >>>> >>>> Where is another place to increase usecnt to 2? >>> It should be >>> ib_create_qp　... >>>     -> rxe_create_qp >>>       -> rxe_qp_from_init >>>          -> rxe_get(pd) <<< pd's refcnt will be increased. >> Isn't rxe_get just increase elem->ref_cnt? > Yes, that's true. I am confused, does increase ref_cnt equal to increase usecnt? If not, then where is another place to increase usecnt to 2? BTW, I traced with 6.3-rc5, seems pd's usecnt is only increase once after create one connection. [ 6941.525088] in init_conns 2353 con_num=3 [ 6941.525732] in create_con_cq_qp 1648 [ 6941.525944] in rtrs_cq_qp_create 311 con->cid=0 path->dev->ib_pd->usecnt=1 [ 6941.532460] in create_con_cq_qp 1648 [ 6941.532746] in rtrs_cq_qp_create 311 con->cid=1 path->dev->ib_pd->usecnt=2 [ 6941.533183] in create_con_cq_qp 1648 [ 6941.533464] in rtrs_cq_qp_create 311 con->cid=2 path->dev->ib_pd->usecnt=3 [ 6941.533685] in init_conns 2365, clt_path->s.dev->ib_pd->usecnt=3 [ 6941.535680] in init_conns 2371, clt_path->s.dev->ib_pd->usecnt=515 Thanks, Guoqing