After sleeping on this, why can't we change __free_pages_bootmem
to not take an order, but rather nr_pages? If we did that,
then __free_pages_memory could just calculate nr_pages and call
__free_pages_bootmem one time.
I don't see why any of the callers of __free_pages_bootmem would not
easily support that change. Maybe I will work that up as part of a -v2
and see if it boots/runs.
At the very least, I think we could change to:
static void __init __free_pages_memory(unsigned long start, unsigned long end)
{
int order;
while (start < end) {
order = ffs(start);
while (start + (1UL << order) > end)
order--;
__free_pages_bootmem(start, order);
start += (1UL << order);
}
}
Robin
On Thu, Jul 11, 2013 at 09:03:53PM -0500, Robin Holt wrote:
> Currently, when free_all_bootmem() calls __free_pages_memory(), the
> number of contiguous pages that __free_pages_memory() passes to the
> buddy allocator is limited to BITS_PER_LONG. In order to be able to
> free only the first page of a 2MiB chunk, we need that to be increased
> to PTRS_PER_PMD.
>
> Signed-off-by: Robin Holt <h...@sgi.com>
> Signed-off-by: Nate Zimmer <nzim...@sgi.com>
> To: "H. Peter Anvin" <h...@zytor.com>
> To: Ingo Molnar <mi...@kernel.org>
> Cc: Linux Kernel <linux-kernel@vger.kernel.org>
> Cc: Linux MM <linux...@kvack.org>
> Cc: Rob Landley <r...@landley.net>
> Cc: Mike Travis <tra...@sgi.com>
> Cc: Daniel J Blueman <dan...@numascale-asia.com>
> Cc: Andrew Morton <a...@linux-foundation.org>
> Cc: Greg KH <gre...@linuxfoundation.org>
> Cc: Yinghai Lu <ying...@kernel.org>
> Cc: Mel Gorman <mgor...@suse.de>
> ---
> mm/nobootmem.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/mm/nobootmem.c b/mm/nobootmem.c
> index bdd3fa2..3b512ca 100644
> --- a/mm/nobootmem.c
> +++ b/mm/nobootmem.c
> @@ -83,10 +83,10 @@ void __init free_bootmem_late(unsigned long addr,
> unsigned long size)
> static void __init __free_pages_memory(unsigned long start, unsigned long
> end)
> {
> unsigned long i, start_aligned, end_aligned;
> - int order = ilog2(BITS_PER_LONG);
> + int order = ilog2(max(BITS_PER_LONG, PTRS_PER_PMD));
>
> - start_aligned = (start + (BITS_PER_LONG - 1)) & ~(BITS_PER_LONG - 1);
> - end_aligned = end & ~(BITS_PER_LONG - 1);
> + start_aligned = (start + ((1UL << order) - 1)) & ~((1UL << order) - 1);
> + end_aligned = end & ~((1UL << order) - 1);
>
> if (end_aligned <= start_aligned) {
> for (i = start; i < end; i++)
> @@ -98,7 +98,7 @@ static void __init __free_pages_memory(unsigned long start,
> unsigned long end)
> for (i = start; i < start_aligned; i++)
> __free_pages_bootmem(pfn_to_page(i), 0);
>
> - for (i = start_aligned; i < end_aligned; i += BITS_PER_LONG)
> + for (i = start_aligned; i < end_aligned; i += 1 << order)
> __free_pages_bootmem(pfn_to_page(i), order);
>
> for (i = end_aligned; i < end; i++)
> --
> 1.8.2.1
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