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>

1 files changed, 56 insertions, 43 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7f25f336551a..12b692164bcc 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1133,19 +1133,65 @@ static int too_many_isolated(struct zone *zone, int file,
 }
 
 /*
+ * 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;
 }