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Date:   Thu, 25 Mar 2021 12:12:17 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Mel Gorman <mgorman@techsingularity.net>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Chuck Lever <chuck.lever@oracle.com>,
        Jesper Dangaard Brouer <brouer@redhat.com>,
        Christoph Hellwig <hch@infradead.org>,
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        Vlastimil Babka <vbabka@suse.cz>,
        Ilias Apalodimas <ilias.apalodimas@linaro.org>,
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        Linux-Net <netdev@vger.kernel.org>,
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Subject: Re: [PATCH 4/9] mm/page_alloc: optimize code layout for
 __alloc_pages_bulk
Message-ID: <20210325121217.GV1719932@casper.infradead.org>
References: <20210325114228.27719-1-mgorman@techsingularity.net>
 <20210325114228.27719-5-mgorman@techsingularity.net>
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On Thu, Mar 25, 2021 at 11:42:23AM +0000, Mel Gorman wrote:
>  
> -	if (WARN_ON_ONCE(nr_pages <= 0))
> +	if (unlikely(nr_pages <= 0))
>  		return 0;

If we made nr_pages unsigned, we wouldn't need this check at all (ok,
we'd still need to figure out what to do with 0).  But then, if a user
inadvertently passes in -ENOMEM, we'll try to allocate 4 billion pages.
So maybe we should check it.  Gah, API design is hard.