linux-kernel - Re: [PATCH V2] mm/memory_hotplug: Drop 'reason' argument from check_pfn

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Message-ID: <YpRQPL7JKNGs63m+@localhost.localdomain>
Date:   Mon, 30 May 2022 07:03:56 +0200
From:   Oscar Salvador <osalvador@...e.de>
To:     Anshuman Khandual <anshuman.khandual@....com>
Cc:     linux-mm@...ck.org, David Hildenbrand <david@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2] mm/memory_hotplug: Drop 'reason' argument from
 check_pfn_span()

On Thu, May 26, 2022 at 07:42:58AM +0530, Anshuman Khandual wrote:
> In check_pfn_span(), a 'reason' string is being used to recreate the caller
> function name, while printing the warning message. It is really unnecessary
> as the warning message could just be printed inside the caller depending on
> the return code. Currently there are just two callers for check_pfn_span()
> i.e  __add_pages() and __remove_pages(). Let's clean this up.
> 
> Cc: Oscar Salvador <osalvador@...e.de>
> Cc: David Hildenbrand <david@...hat.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: linux-mm@...ck.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>

Acked-by: Oscar Salvador <osalvador@...e.de>

> ---
> Changes in V2:
> 
> - Fixed typo in commit message
> - Dropped using 'ret' to capture check_pfn_span() return value in __add_pages()
> 
> Changes in V1:
> 
> https://lore.kernel.org/all/20220525033910.3781764-1-anshuman.khandual@arm.com/
> 
>  mm/memory_hotplug.c | 20 +++++++++-----------
>  1 file changed, 9 insertions(+), 11 deletions(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 416b38ca8def..3b24386e9276 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -220,8 +220,7 @@ static void release_memory_resource(struct resource *res)
>  	kfree(res);
>  }
>  
> -static int check_pfn_span(unsigned long pfn, unsigned long nr_pages,
> -		const char *reason)
> +static int check_pfn_span(unsigned long pfn, unsigned long nr_pages)
>  {
>  	/*
>  	 * Disallow all operations smaller than a sub-section and only
> @@ -238,12 +237,8 @@ static int check_pfn_span(unsigned long pfn, unsigned long nr_pages,
>  		min_align = PAGES_PER_SUBSECTION;
>  	else
>  		min_align = PAGES_PER_SECTION;
> -	if (!IS_ALIGNED(pfn, min_align)
> -			|| !IS_ALIGNED(nr_pages, min_align)) {
> -		WARN(1, "Misaligned __%s_pages start: %#lx end: #%lx\n",
> -				reason, pfn, pfn + nr_pages - 1);
> +	if (!IS_ALIGNED(pfn, min_align) || !IS_ALIGNED(nr_pages, min_align))
>  		return -EINVAL;
> -	}
>  	return 0;
>  }
>  
> @@ -320,9 +315,10 @@ int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
>  		altmap->alloc = 0;
>  	}
>  
> -	err = check_pfn_span(pfn, nr_pages, "add");
> -	if (err)
> -		return err;
> +	if (check_pfn_span(pfn, nr_pages)) {
> +		WARN(1, "Misaligned %s start: %#lx end: #%lx\n", __func__, pfn, pfn + nr_pages - 1);
> +		return -EINVAL;
> +	}
>  
>  	for (; pfn < end_pfn; pfn += cur_nr_pages) {
>  		/* Select all remaining pages up to the next section boundary */
> @@ -518,8 +514,10 @@ void __remove_pages(unsigned long pfn, unsigned long nr_pages,
>  
>  	map_offset = vmem_altmap_offset(altmap);
>  
> -	if (check_pfn_span(pfn, nr_pages, "remove"))
> +	if (check_pfn_span(pfn, nr_pages)) {
> +		WARN(1, "Misaligned %s start: %#lx end: #%lx\n", __func__, pfn, pfn + nr_pages - 1);
>  		return;
> +	}
>  
>  	for (; pfn < end_pfn; pfn += cur_nr_pages) {
>  		cond_resched();
> -- 
> 2.20.1
> 

-- 
Oscar Salvador
SUSE Labs