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    SubjectRe: Prezeroing V3 [1/4]: Allow request for zeroed memory


    On Tue, 4 Jan 2005, Christoph Lameter wrote:
    >
    > This patch introduces __GFP_ZERO as an additional gfp_mask element to allow
    > to request zeroed pages from the page allocator.

    Ok, let's start merging this slowly, and in particular, this 1/4 one looks
    pretty much like a cleanup regardless of whatever else happen, so let's
    just do it. However, for it to really be a cleanup, how about making
    _this_ part:

    > +
    > + if (gfp_flags & __GFP_ZERO) {
    > +#ifdef CONFIG_HIGHMEM
    > + if (PageHighMem(page)) {
    > + int n = 1 << order;
    > +
    > + while (n-- >0)
    > + clear_highpage(page + n);
    > + } else
    > +#endif
    > + clear_page(page_address(page), order);
    > + }

    Match the existing previous part:

    > if (order && (gfp_flags & __GFP_COMP))
    > prep_compound_page(page, order);


    and just split it up into a "prep_zero_page(page, order)"? I dislike
    #ifdef's in the middle of deep functions. In the middle of a _trivial_
    function it's much more palatable.

    At that point at least part 1 ends up being a nice clean patch on its own,
    and should even shrink the code-size a bit. IOW, it not only is a cleanup,
    there is even a technical argument for it (even without worrying about the
    next stages).

    Hmm?

    Linus
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