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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 58CD3C43142 for ; Wed, 1 Aug 2018 00:26:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 192F5208A2 for ; Wed, 1 Aug 2018 00:26:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 192F5208A2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732914AbeHACJS (ORCPT ); Tue, 31 Jul 2018 22:09:18 -0400 Received: from mga03.intel.com ([134.134.136.65]:53042 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732846AbeHACJR (ORCPT ); Tue, 31 Jul 2018 22:09:17 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 31 Jul 2018 17:26:27 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,429,1526367600"; d="scan'208";a="250045147" Received: from djiang5-mobl2.amr.corp.intel.com (HELO [10.255.77.135]) ([10.255.77.135]) by fmsmga005.fm.intel.com with ESMTP; 31 Jul 2018 17:26:23 -0700 Subject: Re: [PATCH] device-dax: avoid hang on error before devm_memremap_pages() To: Stefan Hajnoczi , linux-nvdimm@lists.01.org Cc: linux-kernel@vger.kernel.org, Ross Zwisler , Vishal Verma , Dan Williams References: <20180731143246.16915-1-stefanha@redhat.com> From: Dave Jiang Message-ID: <499a3093-3781-7a8a-abd0-8b240db11dce@intel.com> Date: Tue, 31 Jul 2018 17:26:23 -0700 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: <20180731143246.16915-1-stefanha@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/31/2018 7:32 AM, Stefan Hajnoczi wrote: > dax_pmem_percpu_exit() waits for dax_pmem_percpu_release() to invoke the > dax_pmem->cmp completion. Unfortunately this approach to cleaning up > the percpu_ref only works after devm_memremap_pages() was successful. > > If devm_add_action_or_reset() or devm_memremap_pages() fails, > dax_pmem_percpu_release() is not invoked. Therefore > dax_pmem_percpu_exit() hangs waiting for the completion: > > rc = devm_add_action_or_reset(dev, dax_pmem_percpu_exit, > &dax_pmem->ref); > if (rc) > return rc; > > dax_pmem->pgmap.ref = &dax_pmem->ref; > addr = devm_memremap_pages(dev, &dax_pmem->pgmap); > > Avoid the hang by calling percpu_ref_exit() in the error paths instead > of going through dax_pmem_percpu_exit(). > > Signed-off-by: Stefan Hajnoczi Applied > --- > Found by code inspection. Compile-tested only. > --- > drivers/dax/pmem.c | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c > index fd49b24fd6af..99e2aace8078 100644 > --- a/drivers/dax/pmem.c > +++ b/drivers/dax/pmem.c > @@ -105,15 +105,19 @@ static int dax_pmem_probe(struct device *dev) > if (rc) > return rc; > > - rc = devm_add_action_or_reset(dev, dax_pmem_percpu_exit, > - &dax_pmem->ref); > - if (rc) > + rc = devm_add_action(dev, dax_pmem_percpu_exit, &dax_pmem->ref); > + if (rc) { > + percpu_ref_exit(&dax_pmem->ref); > return rc; > + } > > dax_pmem->pgmap.ref = &dax_pmem->ref; > addr = devm_memremap_pages(dev, &dax_pmem->pgmap); > - if (IS_ERR(addr)) > + if (IS_ERR(addr)) { > + devm_remove_action(dev, dax_pmem_percpu_exit, &dax_pmem->ref); > + percpu_ref_exit(&dax_pmem->ref); > return PTR_ERR(addr); > + } > > rc = devm_add_action_or_reset(dev, dax_pmem_percpu_kill, > &dax_pmem->ref);