> When shrink_inactive_list() isolates pages, it updates a number of
> counters using temporary variables to gather them. These consume stack
> and it's in the main path that calls ->writepage(). This patch moves the
> accounting updates outside of the main path to reduce stack usage.
>
> Signed-off-by: Mel Gorman <mel@xxxxxxxxx>
> ---
> mm/vmscan.c | 63 +++++++++++++++++++++++++++++++++++-----------------------
> 1 files changed, 38 insertions(+), 25 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 2c22c83..4225319 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1061,7 +1061,8 @@ static unsigned long clear_active_flags(struct list_head *page_list,
> ClearPageActive(page);
> nr_active++;
> }
> - count[lru]++;
> + if (count)
> + count[lru]++;
> }
>
> return nr_active;
> @@ -1141,12 +1142,13 @@ static int too_many_isolated(struct zone *zone, int file,
> * TODO: Try merging with migrations version of putback_lru_pages
> */
> static noinline void putback_lru_pages(struct zone *zone,
> - struct zone_reclaim_stat *reclaim_stat,
> + struct scan_control *sc,
> unsigned long nr_anon, unsigned long nr_file,
> struct list_head *page_list)
> {
> struct page *page;
> struct pagevec pvec;
> + struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
Seems unrelated change here.
Otherwise looks good.
- kosaki
>
> pagevec_init(&pvec, 1);
>
> @@ -1185,6 +1187,37 @@ static noinline void putback_lru_pages(struct zone *zone,
> pagevec_release(&pvec);
> }
>
> +static noinline void update_isolated_counts(struct zone *zone,
> + struct scan_control *sc,
> + unsigned long *nr_anon,
> + unsigned long *nr_file,
> + struct list_head *isolated_list)
> +{
> + unsigned long nr_active;
> + unsigned int count[NR_LRU_LISTS] = { 0, };
> + struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
> +
> + nr_active = clear_active_flags(isolated_list, count);
> + __count_vm_events(PGDEACTIVATE, nr_active);
> +
> + __mod_zone_page_state(zone, NR_ACTIVE_FILE,
> + -count[LRU_ACTIVE_FILE]);
> + __mod_zone_page_state(zone, NR_INACTIVE_FILE,
> + -count[LRU_INACTIVE_FILE]);
> + __mod_zone_page_state(zone, NR_ACTIVE_ANON,
> + -count[LRU_ACTIVE_ANON]);
> + __mod_zone_page_state(zone, NR_INACTIVE_ANON,
> + -count[LRU_INACTIVE_ANON]);
> +
> + *nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON];
> + *nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE];
> + __mod_zone_page_state(zone, NR_ISOLATED_ANON, *nr_anon);
> + __mod_zone_page_state(zone, NR_ISOLATED_FILE, *nr_file);
> +
> + reclaim_stat->recent_scanned[0] += *nr_anon;
> + reclaim_stat->recent_scanned[1] += *nr_file;
> +}
> +
> /*
> * shrink_inactive_list() is a helper for shrink_zone(). It returns the number
> * of reclaimed pages
> @@ -1196,11 +1229,9 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
> LIST_HEAD(page_list);
> unsigned long nr_scanned;
> unsigned long nr_reclaimed = 0;
> - struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
> int lumpy_reclaim = 0;
> unsigned long nr_taken;
> unsigned long nr_active;
> - unsigned int count[NR_LRU_LISTS] = { 0, };
> unsigned long nr_anon;
> unsigned long nr_file;
>
> @@ -1244,25 +1275,7 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
> return 0;
> }
>
> - nr_active = clear_active_flags(&page_list, count);
> - __count_vm_events(PGDEACTIVATE, nr_active);
> -
> - __mod_zone_page_state(zone, NR_ACTIVE_FILE,
> - -count[LRU_ACTIVE_FILE]);
> - __mod_zone_page_state(zone, NR_INACTIVE_FILE,
> - -count[LRU_INACTIVE_FILE]);
> - __mod_zone_page_state(zone, NR_ACTIVE_ANON,
> - -count[LRU_ACTIVE_ANON]);
> - __mod_zone_page_state(zone, NR_INACTIVE_ANON,
> - -count[LRU_INACTIVE_ANON]);
> -
> - nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON];
> - nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE];
> - __mod_zone_page_state(zone, NR_ISOLATED_ANON, nr_anon);
> - __mod_zone_page_state(zone, NR_ISOLATED_FILE, nr_file);
> -
> - reclaim_stat->recent_scanned[0] += nr_anon;
> - reclaim_stat->recent_scanned[1] += nr_file;
> + update_isolated_counts(zone, sc, &nr_anon, &nr_file, &page_list);
>
> spin_unlock_irq(&zone->lru_lock);
>
> @@ -1281,7 +1294,7 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
> * The attempt at page out may have made some
> * of the pages active, mark them inactive again.
> */
> - nr_active = clear_active_flags(&page_list, count);
> + nr_active = clear_active_flags(&page_list, NULL);
> count_vm_events(PGDEACTIVATE, nr_active);
>
> nr_reclaimed += shrink_page_list(&page_list, sc,
> @@ -1293,7 +1306,7 @@ 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);
>
> - putback_lru_pages(zone, reclaim_stat, nr_anon, nr_file, &page_list);
> + putback_lru_pages(zone, sc, nr_anon, nr_file, &page_list);
> return nr_reclaimed;
> }
>
> --
> 1.6.5
>
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