linux-kernel - Re: [PATCH 2/2] mm: wrap __find_buddy_pfn() with a necessary buddy page validation.

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Message-ID: <31FDAB92-ACE2-4502-9970-77C21D6EBB5D@nvidia.com>
Date:   Fri, 01 Apr 2022 12:37:11 -0400
From:   Zi Yan <ziy@...dia.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Linux-MM <linux-mm@...ck.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        David Hildenbrand <david@...hat.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Mike Rapoport <rppt@...nel.org>,
        Oscar Salvador <osalvador@...e.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] mm: wrap __find_buddy_pfn() with a necessary buddy page validation.

On 1 Apr 2022, at 12:31, Linus Torvalds wrote:

> On Fri, Apr 1, 2022 at 6:58 AM Zi Yan <zi.yan@...t.com> wrote:
>>
>> +extern bool find_buddy_page_pfn(struct page *page, unsigned int order,
>> +                               struct page **buddy, unsigned long *buddy_pfn);
>
> Wouldn't it make more sense to just return the 'struct page *buddy'
> here, instead of the 'bool'?
>
> So a NULL buddy means the obvious "no buddy found".
>
> I dislike those "pass return value by reference" in general, and the
> above has _two_ of them.
>
> We can get rid of at least one very obviously.

Sure. We can get rid of both and calculate buddy_pfn from buddy after
a successful call.


--
Best Regards,
Yan, Zi

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