vmscan: set up pagevec as late as possible in shrink_inactive_list()

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@csn.ul.ie>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michael Rubin <mrubin@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7f25f33..12b6921 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1132,20 +1132,66 @@ static int too_many_isolated(struct zone *zone, int file,
        return isolated > inactive;
 }
 
+/*
+ * TODO: Try merging with migrations version of putback_lru_pages
+ */
+static noinline_for_stack 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
  */
-static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
-                       struct zone *zone, struct scan_control *sc,
-                       int priority, int file)
+static noinline_for_stack unsigned long
+shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
+                       struct scan_control *sc, int priority, 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);
-       struct page *page;
        unsigned long nr_taken;
        unsigned long nr_active;
        unsigned int count[NR_LRU_LISTS] = { 0, };
@@ -1161,8 +1207,6 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
        }
 
 
-       pagevec_init(&pvec, 1);
-
        lru_add_drain();
        spin_lock_irq(&zone->lru_lock);
 
@@ -1192,8 +1236,10 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
                 */
        }
 
-       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);
@@ -1244,40 +1290,7 @@ 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;
 }