linux-kernel - Re: [PATCH v2] tools/mm: Use calloc and check the memory allocation failure

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Message-Id: <20240830175902.2cbdb98ed746001896f57fe5@linux-foundation.org>
Date: Fri, 30 Aug 2024 17:59:02 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Zhu Jun <zhujun2@...s.chinamobile.com>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] tools/mm: Use calloc and check the memory allocation
 failure

On Thu, 29 Aug 2024 02:21:44 -0700 Zhu Jun <zhujun2@...s.chinamobile.com> wrote:

> Replace malloc with calloc and add null pointer check
> in case of allocation failure.
> 
> ...
>
> --- a/tools/mm/page_owner_sort.c
> +++ b/tools/mm/page_owner_sort.c
> @@ -368,9 +368,10 @@ static __u64 get_ts_nsec(char *buf)
>  
>  static char *get_comm(char *buf)
>  {
> -	char *comm_str = malloc(TASK_COMM_LEN);
> +	char *comm_str = calloc(TASK_COMM_LEN, sizeof(char));
>  
> -	memset(comm_str, 0, TASK_COMM_LEN);
> +	if (!comm_str)
> +		return NULL;

It seems rather pointless doing this when the caller aren't coded to
handle the NULL return.

And really, for these little userspace tools it's OK for us to just
assume that malloc() alway succeeds, isn't it?