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Subject: Re: [PATCH] dax/hmem: Fix refcount leak in dax_hmem_probe()
To:     Ira Weiny <ira.weiny@intel.com>
CC:     <linux-kernel@vger.kernel.org>, <nvdimm@lists.linux.dev>,
        <dan.j.williams@intel.com>, <vishal.l.verma@intel.com>,
        <dave.jiang@intel.com>, <akpm@linux-foundation.org>,
        <joao.m.martins@oracle.com>, <zhangxiaoxu5@huawei.com>
References: <20221203095858.612027-1-liuyongqiang13@huawei.com>
 <Y4u2TK4yPU9dfiDr@iweiny-mobl>
From:   Yongqiang Liu <liuyongqiang13@huawei.com>
Message-ID: <03a5fc74-1b16-a0ee-c0a0-b45943f76bf0@huawei.com>
Date:   Tue, 6 Dec 2022 17:17:33 +0800
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?? 2022/12/4 4:49, Ira Weiny д??:
> On Sat, Dec 03, 2022 at 09:58:58AM +0000, Yongqiang Liu wrote:
>> We should always call dax_region_put() whenever devm_create_dev_dax()
>> succeed or fail to avoid refcount leak of dax_region. Move the return
>> value check after dax_region_put().
> I think dax_region_put is called from dax_region_unregister() automatically on
> tear down.
Yes, Thanks for your explanation.
>> Fixes: c01044cc8191 ("ACPI: HMAT: refactor hmat_register_target_device to hmem_register_device")
> I'm also not sure how this patch is related to this fix.
>
> Ira
>
>> Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>
>> ---
>>   drivers/dax/hmem/hmem.c | 5 ++---
>>   1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
>> index 1bf040dbc834..09f5cd7b6c8e 100644
>> --- a/drivers/dax/hmem/hmem.c
>> +++ b/drivers/dax/hmem/hmem.c
>> @@ -36,12 +36,11 @@ static int dax_hmem_probe(struct platform_device *pdev)
>>   		.size = region_idle ? 0 : resource_size(res),
>>   	};
>>   	dev_dax = devm_create_dev_dax(&data);
>> -	if (IS_ERR(dev_dax))
>> -		return PTR_ERR(dev_dax);
>>   
>>   	/* child dev_dax instances now own the lifetime of the dax_region */
>>   	dax_region_put(dax_region);
>> -	return 0;
>> +
>> +	return IS_ERR(dev_dax) ? PTR_ERR(dev_dax) : 0;
>>   }
>>   
>>   static int dax_hmem_remove(struct platform_device *pdev)
>> -- 
>> 2.25.1
>>
>>
> .