> shrink_page_list() sets up a pagevec to release pages as according as they
> are free. It uses significant amounts of stack on the pagevec. This
> patch adds pages to be freed via pagevec to a linked list which is then
> freed en-masse at the end. This avoids using stack in the main path that
> potentially calls writepage().
>
> Signed-off-by: Mel Gorman <mel@xxxxxxxxx>
> ---
> mm/vmscan.c | 34 ++++++++++++++++++++++++++--------
> 1 files changed, 26 insertions(+), 8 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 9bc1ede..2c22c83 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -619,6 +619,22 @@ static enum page_references page_check_references(struct page *page,
> return PAGEREF_RECLAIM;
> }
>
> +static void free_page_list(struct list_head *free_list)
> +{
> + struct pagevec freed_pvec;
> + struct page *page, *tmp;
> +
> + pagevec_init(&freed_pvec, 1);
> +
> + list_for_each_entry_safe(page, tmp, free_list, lru) {
> + list_del(&page->lru);
> + if (!pagevec_add(&freed_pvec, page)) {
> + __pagevec_free(&freed_pvec);
> + pagevec_reinit(&freed_pvec);
> + }
> + }
Need this two line at this? because we need consider number of
list element are not 14xN.
if (pagevec_count(&freed_pvec))
__pagevec_free(&freed_pvec);
> +}
> +
> /*
> * shrink_page_list() returns the number of reclaimed pages
> */
> @@ -627,13 +643,12 @@ static unsigned long shrink_page_list(struct list_head *page_list,
> enum pageout_io sync_writeback)
> {
> LIST_HEAD(ret_pages);
> - struct pagevec freed_pvec;
> + LIST_HEAD(free_list);
> int pgactivate = 0;
> unsigned long nr_reclaimed = 0;
>
> cond_resched();
>
> - pagevec_init(&freed_pvec, 1);
> while (!list_empty(page_list)) {
> enum page_references references;
> struct address_space *mapping;
> @@ -808,10 +823,12 @@ static unsigned long shrink_page_list(struct list_head *page_list,
> __clear_page_locked(page);
> free_it:
> nr_reclaimed++;
> - if (!pagevec_add(&freed_pvec, page)) {
> - __pagevec_free(&freed_pvec);
> - pagevec_reinit(&freed_pvec);
> - }
> +
> + /*
> + * Is there need to periodically free_page_list? It would
> + * appear not as the counts should be low
> + */
> + list_add(&page->lru, &free_list);
> continue;
>
> cull_mlocked:
> @@ -834,9 +851,10 @@ keep:
> list_add(&page->lru, &ret_pages);
> VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
> }
> +
> + free_page_list(&free_list);
> +
> list_splice(&ret_pages, page_list);
> - if (pagevec_count(&freed_pvec))
> - __pagevec_free(&freed_pvec);
> count_vm_events(PGACTIVATE, pgactivate);
> return nr_reclaimed;
> }
> --
> 1.6.5
>
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