linux-kernel - Re: [PATCH v1] devres: Fix memory leakage due to driver API devm_free

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Date: Wed, 19 Jun 2024 16:53:05 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Zijun Hu <quic_zijuhu@...cinc.com>
Cc: rafael@...nel.org, davem@...emloft.net, madalin.bucur@....com,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v1] devres: Fix memory leakage due to driver API
 devm_free_percpu()

On Wed, Jun 19, 2024 at 09:38:01PM +0800, Zijun Hu wrote:
> It will cause memory leakage when use driver API devm_free_percpu()
> to free memory allocated by devm_alloc_percpu(), fixed by using
> devres_release() instead of devres_destroy() within devm_free_percpu().
> 
> Fixes: ff86aae3b411 ("devres: add devm_alloc_percpu()")
> Cc: stable@...r.kernel.org
> Signed-off-by: Zijun Hu <quic_zijuhu@...cinc.com>
> ---
>  drivers/base/devres.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/devres.c b/drivers/base/devres.c
> index 3df0025d12aa..082dbb296b6e 100644
> --- a/drivers/base/devres.c
> +++ b/drivers/base/devres.c
> @@ -1222,7 +1222,11 @@ EXPORT_SYMBOL_GPL(__devm_alloc_percpu);
>   */
>  void devm_free_percpu(struct device *dev, void __percpu *pdata)
>  {
> -	WARN_ON(devres_destroy(dev, devm_percpu_release, devm_percpu_match,
> +	/*
> +	 * Use devres_release() to prevent memory leakage as
> +	 * devm_free_pages() does.
> +	 */
> +	WARN_ON(devres_release(dev, devm_percpu_release, devm_percpu_match,
>  			       (__force void *)pdata));
>  }
>  EXPORT_SYMBOL_GPL(devm_free_percpu);
> -- 
> 2.7.4
> 
> 

These are good fixes, how are you finding them?  Care to write up some
kunit tests for the devres apis?

thanks,

greg k-h