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Thu, 15 Oct 2020 05:29:03 -0400 X-MC-Unique: NvYuuqNdPMOJwj3qDf8LCA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id ED2C1803629; Thu, 15 Oct 2020 09:29:00 +0000 (UTC) Received: from [10.36.114.207] (ovpn-114-207.ams2.redhat.com [10.36.114.207]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3C6C8610F3; Thu, 15 Oct 2020 09:28:55 +0000 (UTC) Subject: Re: [PATCH 1/2] device-dax/kmem: Fix resource release To: Dan Williams , linux-kernel@vger.kernel.org Cc: Vishal Verma , Dave Hansen , Pavel Tatashin , Brice Goglin , Dave Jiang , Ira Weiny , Jia He , Joao Martins , Jonathan Cameron , akpm@linux-foundation.org, linux-nvdimm@lists.01.org, linux-mm@kvack.org References: <160272252400.3136502.13635752844548960833.stgit@dwillia2-desk3.amr.corp.intel.com> <160272252925.3136502.17220638073995895400.stgit@dwillia2-desk3.amr.corp.intel.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <160272252925.3136502.17220638073995895400.stgit@dwillia2-desk3.amr.corp.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 15.10.20 02:42, Dan Williams wrote: > The conversion to request_mem_region() is broken because it assumes that > the range is marked busy prior to release. However, due to the way that > the kmem driver manipulates the IORESOURCE_BUSY flag (clears it to > let {add,remove}_memory() handle busy) it requires a manual > release_resource() to perform cleanup. > > Given that the actual 'struct resource *' needs to be recalled, not just > the range, add that tracking to the kmem driver-data. > > Reported-by: David Hildenbrand > Fixes: 0513bd5bb114 ("device-dax/kmem: replace release_resource() with release_mem_region()") > Cc: Vishal Verma > Cc: Dave Hansen > Cc: Pavel Tatashin > Cc: Brice Goglin > Cc: Dave Jiang > Cc: Ira Weiny > Cc: Jia He > Cc: Joao Martins > Cc: Jonathan Cameron > Signed-off-by: Dan Williams > --- > drivers/dax/kmem.c | 48 ++++++++++++++++++++++++++++++++++-------------- > 1 file changed, 34 insertions(+), 14 deletions(-) > > diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c > index 6c933f2b604e..af04b6d1d263 100644 > --- a/drivers/dax/kmem.c > +++ b/drivers/dax/kmem.c > @@ -35,11 +35,17 @@ static int dax_kmem_range(struct dev_dax *dev_dax, int i, struct range *r) > return 0; > } > > +struct dax_kmem_data { > + const char *res_name; > + struct resource *res[]; > +}; > + > static int dev_dax_kmem_probe(struct dev_dax *dev_dax) > { > struct device *dev = &dev_dax->dev; > + struct dax_kmem_data *data; > + int rc = -ENOMEM; > int i, mapped = 0; > - char *res_name; > int numa_node; > > /* > @@ -55,14 +61,17 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax) > return -EINVAL; > } > > - res_name = kstrdup(dev_name(dev), GFP_KERNEL); > - if (!res_name) > + data = kzalloc(sizeof(*data) + sizeof(struct resource *) * dev_dax->nr_range, GFP_KERNEL); > + if (!data) > return -ENOMEM; > > + data->res_name = kstrdup(dev_name(dev), GFP_KERNEL); > + if (!data->res_name) > + goto err_res_name; > + > for (i = 0; i < dev_dax->nr_range; i++) { > struct resource *res; > struct range range; > - int rc; > > rc = dax_kmem_range(dev_dax, i, &range); > if (rc) { > @@ -72,7 +81,7 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax) > } > > /* Region is permanently reserved if hotremove fails. */ > - res = request_mem_region(range.start, range_len(&range), res_name); > + res = request_mem_region(range.start, range_len(&range), data->res_name); > if (!res) { > dev_warn(dev, "mapping%d: %#llx-%#llx could not reserve region\n", > i, range.start, range.end); > @@ -82,9 +91,10 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax) > */ > if (mapped) > continue; > - kfree(res_name); > - return -EBUSY; > + rc = -EBUSY; > + goto err_request_mem; > } > + data->res[i] = res; > > /* > * Set flags appropriate for System RAM. Leave ..._BUSY clear > @@ -104,18 +114,25 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax) > if (rc) { > dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n", > i, range.start, range.end); > - release_mem_region(range.start, range_len(&range)); > + release_resource(res); > + kfree(res); > + data->res[i] = NULL; > if (mapped) > continue; > - kfree(res_name); > - return rc; > + goto err_request_mem; > } > mapped++; > } > > - dev_set_drvdata(dev, res_name); > + dev_set_drvdata(dev, data); > > return 0; > + > +err_request_mem: > + kfree(data->res_name); > +err_res_name: > + kfree(data); > + return rc; > } > > #ifdef CONFIG_MEMORY_HOTREMOVE > @@ -123,7 +140,7 @@ static int dev_dax_kmem_remove(struct dev_dax *dev_dax) > { > int i, success = 0; > struct device *dev = &dev_dax->dev; > - const char *res_name = dev_get_drvdata(dev); > + struct dax_kmem_data *data = dev_get_drvdata(dev); > > /* > * We have one shot for removing memory, if some memory blocks were not > @@ -142,7 +159,9 @@ static int dev_dax_kmem_remove(struct dev_dax *dev_dax) > rc = remove_memory(dev_dax->target_node, range.start, > range_len(&range)); > if (rc == 0) { > - release_mem_region(range.start, range_len(&range)); > + release_resource(data->res[i]); > + kfree(data->res[i]); > + data->res[i] = NULL; > success++; > continue; > } > @@ -153,7 +172,8 @@ static int dev_dax_kmem_remove(struct dev_dax *dev_dax) > } > > if (success >= dev_dax->nr_range) { > - kfree(res_name); > + kfree(data->res_name); > + kfree(data); > dev_set_drvdata(dev, NULL); > } > > Looks sane to me Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb