linux-kernel - Re: [PATCH 1/2] mm: vmpressure: don't need call kfree if kstrndup fails

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Date:   Wed, 12 Feb 2020 20:51:22 -0800
From:   Yang Shi <yang.shi@...ux.alibaba.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     David Hildenbrand <david@...hat.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] mm: vmpressure: don't need call kfree if kstrndup
 fails



On 2/12/20 8:48 PM, Andrew Morton wrote:
> On Wed, 12 Feb 2020 19:14:27 -0800 Yang Shi <yang.shi@...ux.alibaba.com> wrote:
>
>> On 2/12/20 3:21 AM, David Hildenbrand wrote:
>>> On 11.02.20 06:24, Yang Shi wrote:
>>>> When kstrndup fails (returns NULL) there is no memory is allocated by
>>>> kmalloc, so no need to call kfree().
>>> "When kstrndup fails, no memory was allocated and we can exit directly."
>> Thanks for correcting the commit log.
>>
>> Andrew, do you prefer I send an updated version or you would just update
>> the patch in -mm tree?
> I have already done this.

Thanks!

>
> From: Yang Shi <yang.shi@...ux.alibaba.com>
> Subject: mm: vmpressure: don't need call kfree if kstrndup fails
>
> When kstrndup fails, no memory was allocated and we can exit directly.
>
> [david@...hat.com: reword changelog]
> Link: http://lkml.kernel.org/r/1581398649-125989-1-git-send-email-yang.shi@linux.alibaba.com
> Signed-off-by: Yang Shi <yang.shi@...ux.alibaba.com>
> Reviewed-by: Andrew Morton <akpm@...ux-foundation.org>
> Reviewed-by: David Hildenbrand <david@...hat.com>
> Acked-by: David Rientjes <rientjes@...gle.com>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> ---
>
>   mm/vmpressure.c |    6 ++----
>   1 file changed, 2 insertions(+), 4 deletions(-)
>
> --- a/mm/vmpressure.c~mm-vmpressure-dont-need-call-kfree-if-kstrndup-fails
> +++ a/mm/vmpressure.c
> @@ -371,10 +371,8 @@ int vmpressure_register_event(struct mem
>   	int ret = 0;
>   
>   	spec_orig = spec = kstrndup(args, MAX_VMPRESSURE_ARGS_LEN, GFP_KERNEL);
> -	if (!spec) {
> -		ret = -ENOMEM;
> -		goto out;
> -	}
> +	if (!spec)
> +		return -ENOMEM;
>   
>   	/* Find required level */
>   	token = strsep(&spec, ",");
> _