linux-kernel - Re: [PATCH 2/2] mm,memory_hotplug: print the min alignment in check_pfn

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Message-ID: <adcc88c9-6e75-07a1-2d3d-7fa4bda88137@redhat.com>
Date:   Wed, 2 Jun 2021 11:01:49 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Max Gurtovoy <mgurtovoy@...dia.com>, akpm@...ux-foundation.org,
        linux-mm@...ck.org
Cc:     pasha.tatashin@...een.com, linux-kernel@...r.kernel.org,
        logang@...tatee.com
Subject: Re: [PATCH 2/2] mm,memory_hotplug: print the min alignment in
 check_pfn_span

On 02.06.21 10:47, Max Gurtovoy wrote:
> The warning only prints the start and end pfns. Add min_align to the
> warning print to add more info regarding the failure.
> 
> Signed-off-by: Max Gurtovoy <mgurtovoy@...dia.com>
> ---
>   mm/memory_hotplug.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 8c3b423c1141..9e86e9ee0a10 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -289,8 +289,8 @@ static int check_pfn_span(unsigned long pfn, unsigned long nr_pages,
>   	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);
> +		WARN(1, "Misaligned __%s_pages min_align: %#lx start: %#lx end: %#lx\n",
> +		     reason, min_align, pfn, pfn + nr_pages - 1);
>   		return -EINVAL;
>   	}
>   	return 0;
> 

Not sure if we really care. I expect only developers will run into that 
hacking on something new, and they will have to dig deeper either way.

While at it, I'd suggest converting this to pr_warn(), as WARN() is 
frowned upon as it can crash the kernel with panic_on_warn as set by 
some distros.

Reviewed-by: David Hildenbrand <david@...hat.com>

-- 
Thanks,

David / dhildenb