| Date | Wed, 18 Dec 2019 18:52:11 +0300 | From | "Kirill A. Shutemov" <> | Subject | Re: [PATCH v11 01/25] mm/gup: factor out duplicate code from four routines |
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On Mon, Dec 16, 2019 at 02:25:13PM -0800, John Hubbard wrote: > +static void put_compound_head(struct page *page, int refs) > +{ > + /* Do a get_page() first, in case refs == page->_refcount */ > + get_page(page); > + page_ref_sub(page, refs); > + put_page(page); > +}
It's not terribly efficient. Maybe something like:
VM_BUG_ON_PAGE(page_ref_count(page) < ref, page); if (refs > 2) page_ref_sub(page, refs - 1); put_page(page);
?
-- Kirill A. Shutemov
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