linux-kernel - Re: [PATCH] dax/hmem: Fix refcount leak in dax_hmem

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Date:   Sat, 3 Dec 2022 12:49:16 -0800
From:   Ira Weiny <ira.weiny@...el.com>
To:     Yongqiang Liu <liuyongqiang13@...wei.com>
CC:     <linux-kernel@...r.kernel.org>, <nvdimm@...ts.linux.dev>,
        <dan.j.williams@...el.com>, <vishal.l.verma@...el.com>,
        <dave.jiang@...el.com>, <akpm@...ux-foundation.org>,
        <joao.m.martins@...cle.com>, <zhangxiaoxu5@...wei.com>
Subject: Re: [PATCH] dax/hmem: Fix refcount leak in dax_hmem_probe()

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.

> 
> 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@...wei.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
> 
>