On Mon, Nov 12 2012, Marek Szyprowski wrote:
> Memory return to free_contig_range() must have no other references. Let
> kernel to complain loudly if page reference count is not equal to 1.
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 022e4ed..290c2eb 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5888,8 +5888,13 @@ done:
>
> void free_contig_range(unsigned long pfn, unsigned nr_pages)
> {
> - for (; nr_pages--; ++pfn)
> - __free_page(pfn_to_page(pfn));
> + struct page *page = pfn_to_page(pfn);
> + int refcount = nr_pages;
> + for (; nr_pages--; page++) {
> + refcount -= page_count(page) == 1;
> + __free_page(page);
> + }
> + WARN(refcount != 0, "some pages are still in use!\n");
This decrementing logic seem backward to me. Why not:
struct page *page = pfn_to_page(pfn);
unsigned int refcount = 0;
for (; nr_pages--; page++) {
refcount += page_count(page) != 1;
__free_page(page);
}
WARN(refcount != 0, "some pages are still in use!\n");
> }
> #endif
--
Best regards, _ _
.o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o
..o | Computer Science, Michał “mina86” Nazarewicz (o o)
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