> shrink_inactive_list() sets up a pagevec to release unfreeable pages. It
> uses significant amounts of stack doing this. This patch splits
> shrink_inactive_list() to take the stack usage out of the main path so
> that callers to writepage() do not contain an unused pagevec on the
> stack.
>
> Signed-off-by: Mel Gorman <mel@xxxxxxxxx>
> ---
> mm/vmscan.c | 93 +++++++++++++++++++++++++++++++++-------------------------
> 1 files changed, 53 insertions(+), 40 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index a232ad6..9bc1ede 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1120,6 +1120,54 @@ static int too_many_isolated(struct zone *zone, int file,
> }
>
> /*
> + * TODO: Try merging with migrations version of putback_lru_pages
> + */
I also think this stuff need more cleanups. but this patch works and
no downside. So, Let's merge this at first.
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
but please fix Dave's pointed one.
> +static noinline void putback_lru_pages(struct zone *zone,
> + struct zone_reclaim_stat *reclaim_stat,
> + unsigned long nr_anon, unsigned long nr_file,
> + struct list_head *page_list)
> +{
> + struct page *page;
> + struct pagevec pvec;
> +
> + pagevec_init(&pvec, 1);
> +
> + /*
> + * Put back any unfreeable pages.
> + */
> + spin_lock(&zone->lru_lock);
> + while (!list_empty(page_list)) {
> + int lru;
> + page = lru_to_page(page_list);
> + VM_BUG_ON(PageLRU(page));
> + list_del(&page->lru);
> + if (unlikely(!page_evictable(page, NULL))) {
> + spin_unlock_irq(&zone->lru_lock);
> + putback_lru_page(page);
> + spin_lock_irq(&zone->lru_lock);
> + continue;
> + }
> + SetPageLRU(page);
> + lru = page_lru(page);
> + add_page_to_lru_list(zone, page, lru);
> + if (is_active_lru(lru)) {
> + int file = is_file_lru(lru);
> + reclaim_stat->recent_rotated[file]++;
> + }
> + if (!pagevec_add(&pvec, page)) {
> + spin_unlock_irq(&zone->lru_lock);
> + __pagevec_release(&pvec);
> + spin_lock_irq(&zone->lru_lock);
> + }
> + }
> + __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon);
> + __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file);
> +
> + spin_unlock_irq(&zone->lru_lock);
> + pagevec_release(&pvec);
> +}
> +
> +/*
> * shrink_inactive_list() is a helper for shrink_zone(). It returns the number
> * of reclaimed pages
> */
> @@ -1128,12 +1176,10 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
> int file)
> {
> LIST_HEAD(page_list);
> - struct pagevec pvec;
> unsigned long nr_scanned;
> unsigned long nr_reclaimed = 0;
> struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
> int lumpy_reclaim = 0;
> - struct page *page;
> unsigned long nr_taken;
> unsigned long nr_active;
> unsigned int count[NR_LRU_LISTS] = { 0, };
> @@ -1160,8 +1206,6 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
> else if (sc->order && sc->priority < DEF_PRIORITY - 2)
> lumpy_reclaim = 1;
>
> - pagevec_init(&pvec, 1);
> -
> lru_add_drain();
> spin_lock_irq(&zone->lru_lock);
> nr_taken = sc->isolate_pages(nr_to_scan,
> @@ -1177,8 +1221,10 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
> __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scanned);
> }
>
> - if (nr_taken == 0)
> - goto done;
> + if (nr_taken == 0) {
> + spin_unlock_irq(&zone->lru_lock);
> + return 0;
> + }
>
> nr_active = clear_active_flags(&page_list, count);
> __count_vm_events(PGDEACTIVATE, nr_active);
> @@ -1229,40 +1275,7 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
> __count_vm_events(KSWAPD_STEAL, nr_reclaimed);
> __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed);
>
> - spin_lock(&zone->lru_lock);
> - /*
> - * Put back any unfreeable pages.
> - */
> - while (!list_empty(&page_list)) {
> - int lru;
> - page = lru_to_page(&page_list);
> - VM_BUG_ON(PageLRU(page));
> - list_del(&page->lru);
> - if (unlikely(!page_evictable(page, NULL))) {
> - spin_unlock_irq(&zone->lru_lock);
> - putback_lru_page(page);
> - spin_lock_irq(&zone->lru_lock);
> - continue;
> - }
> - SetPageLRU(page);
> - lru = page_lru(page);
> - add_page_to_lru_list(zone, page, lru);
> - if (is_active_lru(lru)) {
> - int file = is_file_lru(lru);
> - reclaim_stat->recent_rotated[file]++;
> - }
> - if (!pagevec_add(&pvec, page)) {
> - spin_unlock_irq(&zone->lru_lock);
> - __pagevec_release(&pvec);
> - spin_lock_irq(&zone->lru_lock);
> - }
> - }
> - __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon);
> - __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file);
> -
> -done:
> - spin_unlock_irq(&zone->lru_lock);
> - pagevec_release(&pvec);
> + putback_lru_pages(zone, reclaim_stat, nr_anon, nr_file, &page_list);
> return nr_reclaimed;
> }
>
> --
> 1.6.5
>
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