Re: [PATCH 2/2] page-allocator: Maintain rolling count of pages to free from the PCP

[Pekka Enberg <penberg@cs.helsinki.fi>]

Hi Mel,

On Fri, Aug 28, 2009 at 11:44 AM, Mel Gorman<mel@csn.ul.ie> wrote:
> -               page = list_entry(list->prev, struct page, lru);
> -               /* have to delete it as __free_one_page list manipulates */
> -               list_del(&page->lru);
> -               trace_mm_page_pcpu_drain(page, 0, migratetype);
> -               __free_one_page(page, zone, 0, migratetype);
> +               do {
> +                       page = list_entry(list->prev, struct page, lru);
> +                       /* must delete as __free_one_page list manipulates */
> +                       list_del(&page->lru);
> +                       __free_one_page(page, zone, 0, migratetype);
> +                       trace_mm_page_pcpu_drain(page, 0, migratetype);

This calls trace_mm_page_pcpu_drain() *after* __free_one_page(). It's
probably not a good idea as __free_one_page() can alter the struct
page in various ways.

> +               } while (--count && --batch_free && !list_empty(list));
>        }
>        spin_unlock(&zone->lock);
>  }

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