1 files changed, 79 insertions, 32 deletions

diff --git a/mm/swap.c b/mm/swap.c
index d3cb966fe992..a65eff8a517a 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -24,16 +24,19 @@
 #include <linux/module.h>
 #include <linux/mm_inline.h>
 #include <linux/buffer_head.h>  /* for try_to_release_page() */
-#include <linux/module.h>
 #include <linux/percpu_counter.h>
 #include <linux/percpu.h>
 #include <linux/cpu.h>
 #include <linux/notifier.h>
-#include <linux/init.h>
+#include <linux/backing-dev.h>
 
 /* How many pages do we try to swap or page in/out together? */
 int page_cluster;
 
+static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, };
+static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, };
+static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs) = { 0, };
+
 /*
  * This path almost never happens for VM activity - pages are normally
  * freed via pagevecs.  But it gets used by networking.
@@ -94,23 +97,47 @@ void put_pages_list(struct list_head *pages)
 EXPORT_SYMBOL(put_pages_list);
 
 /*
+ * pagevec_move_tail() must be called with IRQ disabled.
+ * Otherwise this may cause nasty races.
+ */
+static void pagevec_move_tail(struct pagevec *pvec)
+{
+        int i;
+        int pgmoved = 0;
+        struct zone *zone = NULL;
+
+        for (i = 0; i < pagevec_count(pvec); i++) {
+                struct page *page = pvec->pages[i];
+                struct zone *pagezone = page_zone(page);
+
+                if (pagezone != zone) {
+                        if (zone)
+                                spin_unlock(&zone->lru_lock);
+                        zone = pagezone;
+                        spin_lock(&zone->lru_lock);
+                }
+                if (PageLRU(page) && !PageActive(page)) {
+                        list_move_tail(&page->lru, &zone->inactive_list);
+                        pgmoved++;
+                }
+        }
+        if (zone)
+                spin_unlock(&zone->lru_lock);
+        __count_vm_events(PGROTATED, pgmoved);
+        release_pages(pvec->pages, pvec->nr, pvec->cold);
+        pagevec_reinit(pvec);
+}
+
+/*
  * Writeback is about to end against a page which has been marked for immediate
  * reclaim.  If it still appears to be reclaimable, move it to the tail of the
- * inactive list.  The page still has PageWriteback set, which will pin it.
- *
- * We don't expect many pages to come through here, so don't bother batching
- * things up.
- *
- * To avoid placing the page at the tail of the LRU while PG_writeback is still
- * set, this function will clear PG_writeback before performing the page
- * motion.  Do that inside the lru lock because once PG_writeback is cleared
- * we may not touch the page.
+ * inactive list.
  *
  * Returns zero if it cleared PG_writeback.
  */
 int rotate_reclaimable_page(struct page *page)
 {
-        struct zone *zone;
+        struct pagevec *pvec;
         unsigned long flags;
 
         if (PageLocked(page))
@@ -122,15 +149,16 @@ int rotate_reclaimable_page(struct page *page)
         if (!PageLRU(page))
                 return 1;
 
-        zone = page_zone(page);
-        spin_lock_irqsave(&zone->lru_lock, flags);
-        if (PageLRU(page) && !PageActive(page)) {
-                list_move_tail(&page->lru, &zone->inactive_list);
-                __count_vm_event(PGROTATED);
-        }
+        page_cache_get(page);
+        local_irq_save(flags);
+        pvec = &__get_cpu_var(lru_rotate_pvecs);
+        if (!pagevec_add(pvec, page))
+                pagevec_move_tail(pvec);
+        local_irq_restore(flags);
+
         if (!test_clear_page_writeback(page))
                 BUG();
-        spin_unlock_irqrestore(&zone->lru_lock, flags);
+
         return 0;
 }
 
@@ -174,9 +202,6 @@ EXPORT_SYMBOL(mark_page_accessed);
  * lru_cache_add: add a page to the page lists
  * @page: the page to add
  */
-static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, };
-static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, };
-
 void fastcall lru_cache_add(struct page *page)
 {
         struct pagevec *pvec = &get_cpu_var(lru_add_pvecs);
@@ -197,21 +222,37 @@ void fastcall lru_cache_add_active(struct page *page)
         put_cpu_var(lru_add_active_pvecs);
 }
 
-static void __lru_add_drain(int cpu)
+/*
+ * Drain pages out of the cpu's pagevecs.
+ * Either "cpu" is the current CPU, and preemption has already been
+ * disabled; or "cpu" is being hot-unplugged, and is already dead.
+ */
+static void drain_cpu_pagevecs(int cpu)
 {
-        struct pagevec *pvec = &per_cpu(lru_add_pvecs, cpu);
+        struct pagevec *pvec;
 
-        /* CPU is dead, so no locking needed. */
+        pvec = &per_cpu(lru_add_pvecs, cpu);
         if (pagevec_count(pvec))
                 __pagevec_lru_add(pvec);
+
         pvec = &per_cpu(lru_add_active_pvecs, cpu);
         if (pagevec_count(pvec))
                 __pagevec_lru_add_active(pvec);
+
+        pvec = &per_cpu(lru_rotate_pvecs, cpu);
+        if (pagevec_count(pvec)) {
+                unsigned long flags;
+
+                /* No harm done if a racing interrupt already did this */
+                local_irq_save(flags);
+                pagevec_move_tail(pvec);
+                local_irq_restore(flags);
+        }
 }
 
 void lru_add_drain(void)
 {
-        __lru_add_drain(get_cpu());
+        drain_cpu_pagevecs(get_cpu());
         put_cpu();
 }
 
@@ -258,6 +299,7 @@ void release_pages(struct page **pages, int nr, int cold)
         int i;
         struct pagevec pages_to_free;
         struct zone *zone = NULL;
+        unsigned long uninitialized_var(flags);
 
         pagevec_init(&pages_to_free, cold);
         for (i = 0; i < nr; i++) {
@@ -265,7 +307,7 @@ void release_pages(struct page **pages, int nr, int cold)
 
                 if (unlikely(PageCompound(page))) {
                         if (zone) {
-                                spin_unlock_irq(&zone->lru_lock);
+                                spin_unlock_irqrestore(&zone->lru_lock, flags);
                                 zone = NULL;
                         }
                         put_compound_page(page);
@@ -279,9 +321,10 @@ void release_pages(struct page **pages, int nr, int cold)
                         struct zone *pagezone = page_zone(page);
                         if (pagezone != zone) {
                                 if (zone)
-                                        spin_unlock_irq(&zone->lru_lock);
+                                        spin_unlock_irqrestore(&zone->lru_lock,
+                                                                        flags);
                                 zone = pagezone;
-                                spin_lock_irq(&zone->lru_lock);
+                                spin_lock_irqsave(&zone->lru_lock, flags);
                         }
                         VM_BUG_ON(!PageLRU(page));
                         __ClearPageLRU(page);
@@ -290,7 +333,7 @@ void release_pages(struct page **pages, int nr, int cold)
 
                 if (!pagevec_add(&pages_to_free, page)) {
                         if (zone) {
-                                spin_unlock_irq(&zone->lru_lock);
+                                spin_unlock_irqrestore(&zone->lru_lock, flags);
                                 zone = NULL;
                         }
                         __pagevec_free(&pages_to_free);
@@ -298,7 +341,7 @@ void release_pages(struct page **pages, int nr, int cold)
                 }
         }
         if (zone)
-                spin_unlock_irq(&zone->lru_lock);
+                spin_unlock_irqrestore(&zone->lru_lock, flags);
 
         pagevec_free(&pages_to_free);
 }
@@ -491,7 +534,7 @@ static int cpu_swap_callback(struct notifier_block *nfb,
         if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
                 atomic_add(*committed, &vm_committed_space);
                 *committed = 0;
-                __lru_add_drain((long)hcpu);
+                drain_cpu_pagevecs((long)hcpu);
         }
         return NOTIFY_OK;
 }
@@ -505,6 +548,10 @@ void __init swap_setup(void)
 {
         unsigned long megs = num_physpages >> (20 - PAGE_SHIFT);
 
+#ifdef CONFIG_SWAP
+        bdi_init(swapper_space.backing_dev_info);
+#endif
+
         /* Use a smaller cluster for small-memory machines */
         if (megs < 16)
                 page_cluster = 2;