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Tue, 12 May 2020 14:36:57 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 04CESNMe105391; Tue, 12 May 2020 14:36:56 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3020.oracle.com with ESMTP id 30x69tbdhj-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 12 May 2020 14:36:56 +0000 Received: from abhmp0019.oracle.com (abhmp0019.oracle.com [141.146.116.25]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 04CEasTW008459; Tue, 12 May 2020 14:36:54 GMT Received: from [10.175.218.127] (/10.175.218.127) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 12 May 2020 07:36:54 -0700 Subject: Re: [PATCH 11/12] device-dax: Add dis-contiguous resource support To: Dan Williams Cc: linux-mm@kvack.org, vishal.l.verma@intel.com, dave.hansen@linux.intel.com, hch@lst.de, linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org, jmoyer@redhat.com References: <158500767138.2088294.17131646259803932461.stgit@dwillia2-desk3.amr.corp.intel.com> <158500773552.2088294.8756587190550753100.stgit@dwillia2-desk3.amr.corp.intel.com> From: Joao Martins Message-ID: Date: Tue, 12 May 2020 15:36:50 +0100 MIME-Version: 1.0 In-Reply-To: <158500773552.2088294.8756587190550753100.stgit@dwillia2-desk3.amr.corp.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9618 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 malwarescore=0 adultscore=0 spamscore=0 suspectscore=5 mlxscore=0 mlxlogscore=999 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2005120109 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9618 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 impostorscore=0 mlxscore=0 suspectscore=5 bulkscore=0 mlxlogscore=999 phishscore=0 malwarescore=0 lowpriorityscore=0 spamscore=0 adultscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2005120110 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/23/20 11:55 PM, Dan Williams wrote: > @@ -561,13 +580,26 @@ static int __alloc_dev_dax_range(struct dev_dax *dev_dax, u64 start, > if (start == U64_MAX) > return -EINVAL; > > + ranges = krealloc(dev_dax->ranges, sizeof(*ranges) > + * (dev_dax->nr_range + 1), GFP_KERNEL); > + if (!ranges) > + return -ENOMEM; > + > alloc = __request_region(res, start, size, dev_name(dev), 0); > - if (!alloc) > + if (!alloc) { > + kfree(ranges); > return -ENOMEM; > + } Noticed this yesterday while looking at alloc_dev_dax_range(). Is it correct to free @ranges here on __request_region failure? IIUC krealloc() would free dev_dax->ranges if it succeeds, leaving us without any valid ranges if __request_region failure case indeed frees @ranges. These @ranges are being used afterwards when we delete the interface and free the assigned regions. Perhaps we should remove the kfree() above and set dev_dax->ranges instead before __request_region; or alternatively change the call order between krealloc and __request_region? FWIW, krealloc checks if the object being reallocated already meets the requested size, so perhaps there's no harm with going with the former. Joao