1 files changed, 485 insertions, 0 deletions

diff --git a/mm/swap.c b/mm/swap.c
new file mode 100644
index 000000000000..7771d2803f62
--- /dev/null
+++ b/mm/swap.c
@@ -0,0 +1,485 @@
+/*
+ *  linux/mm/swap.c
+ *
+ *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
+ */
+
+/*
+ * This file contains the default values for the opereation of the
+ * Linux VM subsystem. Fine-tuning documentation can be found in
+ * Documentation/sysctl/vm.txt.
+ * Started 18.12.91
+ * Swap aging added 23.2.95, Stephen Tweedie.
+ * Buffermem limits added 12.3.98, Rik van Riel.
+ */
+
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/kernel_stat.h>
+#include <linux/swap.h>
+#include <linux/mman.h>
+#include <linux/pagemap.h>
+#include <linux/pagevec.h>
+#include <linux/init.h>
+#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>
+
+/* How many pages do we try to swap or page in/out together? */
+int page_cluster;
+
+#ifdef CONFIG_HUGETLB_PAGE
+
+void put_page(struct page *page)
+{
+        if (unlikely(PageCompound(page))) {
+                page = (struct page *)page->private;
+                if (put_page_testzero(page)) {
+                        void (*dtor)(struct page *page);
+
+                        dtor = (void (*)(struct page *))page[1].mapping;
+                        (*dtor)(page);
+                }
+                return;
+        }
+        if (!PageReserved(page) && put_page_testzero(page))
+                __page_cache_release(page);
+}
+EXPORT_SYMBOL(put_page);
+#endif
+
+/*
+ * 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.
+ *
+ * Returns zero if it cleared PG_writeback.
+ */
+int rotate_reclaimable_page(struct page *page)
+{
+        struct zone *zone;
+        unsigned long flags;
+
+        if (PageLocked(page))
+                return 1;
+        if (PageDirty(page))
+                return 1;
+        if (PageActive(page))
+                return 1;
+        if (!PageLRU(page))
+                return 1;
+
+        zone = page_zone(page);
+        spin_lock_irqsave(&zone->lru_lock, flags);
+        if (PageLRU(page) && !PageActive(page)) {
+                list_del(&page->lru);
+                list_add_tail(&page->lru, &zone->inactive_list);
+                inc_page_state(pgrotated);
+        }
+        if (!test_clear_page_writeback(page))
+                BUG();
+        spin_unlock_irqrestore(&zone->lru_lock, flags);
+        return 0;
+}
+
+/*
+ * FIXME: speed this up?
+ */
+void fastcall activate_page(struct page *page)
+{
+        struct zone *zone = page_zone(page);
+
+        spin_lock_irq(&zone->lru_lock);
+        if (PageLRU(page) && !PageActive(page)) {
+                del_page_from_inactive_list(zone, page);
+                SetPageActive(page);
+                add_page_to_active_list(zone, page);
+                inc_page_state(pgactivate);
+        }
+        spin_unlock_irq(&zone->lru_lock);
+}
+
+/*
+ * Mark a page as having seen activity.
+ *
+ * inactive,unreferenced        ->      inactive,referenced
+ * inactive,referenced          ->      active,unreferenced
+ * active,unreferenced          ->      active,referenced
+ */
+void fastcall mark_page_accessed(struct page *page)
+{
+        if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) {
+                activate_page(page);
+                ClearPageReferenced(page);
+        } else if (!PageReferenced(page)) {
+                SetPageReferenced(page);
+        }
+}
+
+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);
+
+        page_cache_get(page);
+        if (!pagevec_add(pvec, page))
+                __pagevec_lru_add(pvec);
+        put_cpu_var(lru_add_pvecs);
+}
+
+void fastcall lru_cache_add_active(struct page *page)
+{
+        struct pagevec *pvec = &get_cpu_var(lru_add_active_pvecs);
+
+        page_cache_get(page);
+        if (!pagevec_add(pvec, page))
+                __pagevec_lru_add_active(pvec);
+        put_cpu_var(lru_add_active_pvecs);
+}
+
+void lru_add_drain(void)
+{
+        struct pagevec *pvec = &get_cpu_var(lru_add_pvecs);
+
+        if (pagevec_count(pvec))
+                __pagevec_lru_add(pvec);
+        pvec = &__get_cpu_var(lru_add_active_pvecs);
+        if (pagevec_count(pvec))
+                __pagevec_lru_add_active(pvec);
+        put_cpu_var(lru_add_pvecs);
+}
+
+/*
+ * This path almost never happens for VM activity - pages are normally
+ * freed via pagevecs.  But it gets used by networking.
+ */
+void fastcall __page_cache_release(struct page *page)
+{
+        unsigned long flags;
+        struct zone *zone = page_zone(page);
+
+        spin_lock_irqsave(&zone->lru_lock, flags);
+        if (TestClearPageLRU(page))
+                del_page_from_lru(zone, page);
+        if (page_count(page) != 0)
+                page = NULL;
+        spin_unlock_irqrestore(&zone->lru_lock, flags);
+        if (page)
+                free_hot_page(page);
+}
+
+EXPORT_SYMBOL(__page_cache_release);
+
+/*
+ * Batched page_cache_release().  Decrement the reference count on all the
+ * passed pages.  If it fell to zero then remove the page from the LRU and
+ * free it.
+ *
+ * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
+ * for the remainder of the operation.
+ *
+ * The locking in this function is against shrink_cache(): we recheck the
+ * page count inside the lock to see whether shrink_cache grabbed the page
+ * via the LRU.  If it did, give up: shrink_cache will free it.
+ */
+void release_pages(struct page **pages, int nr, int cold)
+{
+        int i;
+        struct pagevec pages_to_free;
+        struct zone *zone = NULL;
+
+        pagevec_init(&pages_to_free, cold);
+        for (i = 0; i < nr; i++) {
+                struct page *page = pages[i];
+                struct zone *pagezone;
+
+                if (PageReserved(page) || !put_page_testzero(page))
+                        continue;
+
+                pagezone = page_zone(page);
+                if (pagezone != zone) {
+                        if (zone)
+                                spin_unlock_irq(&zone->lru_lock);
+                        zone = pagezone;
+                        spin_lock_irq(&zone->lru_lock);
+                }
+                if (TestClearPageLRU(page))
+                        del_page_from_lru(zone, page);
+                if (page_count(page) == 0) {
+                        if (!pagevec_add(&pages_to_free, page)) {
+                                spin_unlock_irq(&zone->lru_lock);
+                                __pagevec_free(&pages_to_free);
+                                pagevec_reinit(&pages_to_free);
+                                zone = NULL;    /* No lock is held */
+                        }
+                }
+        }
+        if (zone)
+                spin_unlock_irq(&zone->lru_lock);
+
+        pagevec_free(&pages_to_free);
+}
+
+/*
+ * The pages which we're about to release may be in the deferred lru-addition
+ * queues.  That would prevent them from really being freed right now.  That's
+ * OK from a correctness point of view but is inefficient - those pages may be
+ * cache-warm and we want to give them back to the page allocator ASAP.
+ *
+ * So __pagevec_release() will drain those queues here.  __pagevec_lru_add()
+ * and __pagevec_lru_add_active() call release_pages() directly to avoid
+ * mutual recursion.
+ */
+void __pagevec_release(struct pagevec *pvec)
+{
+        lru_add_drain();
+        release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
+        pagevec_reinit(pvec);
+}
+
+/*
+ * pagevec_release() for pages which are known to not be on the LRU
+ *
+ * This function reinitialises the caller's pagevec.
+ */
+void __pagevec_release_nonlru(struct pagevec *pvec)
+{
+        int i;
+        struct pagevec pages_to_free;
+
+        pagevec_init(&pages_to_free, pvec->cold);
+        pages_to_free.cold = pvec->cold;
+        for (i = 0; i < pagevec_count(pvec); i++) {
+                struct page *page = pvec->pages[i];
+
+                BUG_ON(PageLRU(page));
+                if (put_page_testzero(page))
+                        pagevec_add(&pages_to_free, page);
+        }
+        pagevec_free(&pages_to_free);
+        pagevec_reinit(pvec);
+}
+
+/*
+ * Add the passed pages to the LRU, then drop the caller's refcount
+ * on them.  Reinitialises the caller's pagevec.
+ */
+void __pagevec_lru_add(struct pagevec *pvec)
+{
+        int i;
+        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_irq(&zone->lru_lock);
+                        zone = pagezone;
+                        spin_lock_irq(&zone->lru_lock);
+                }
+                if (TestSetPageLRU(page))
+                        BUG();
+                add_page_to_inactive_list(zone, page);
+        }
+        if (zone)
+                spin_unlock_irq(&zone->lru_lock);
+        release_pages(pvec->pages, pvec->nr, pvec->cold);
+        pagevec_reinit(pvec);
+}
+
+EXPORT_SYMBOL(__pagevec_lru_add);
+
+void __pagevec_lru_add_active(struct pagevec *pvec)
+{
+        int i;
+        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_irq(&zone->lru_lock);
+                        zone = pagezone;
+                        spin_lock_irq(&zone->lru_lock);
+                }
+                if (TestSetPageLRU(page))
+                        BUG();
+                if (TestSetPageActive(page))
+                        BUG();
+                add_page_to_active_list(zone, page);
+        }
+        if (zone)
+                spin_unlock_irq(&zone->lru_lock);
+        release_pages(pvec->pages, pvec->nr, pvec->cold);
+        pagevec_reinit(pvec);
+}
+
+/*
+ * Try to drop buffers from the pages in a pagevec
+ */
+void pagevec_strip(struct pagevec *pvec)
+{
+        int i;
+
+        for (i = 0; i < pagevec_count(pvec); i++) {
+                struct page *page = pvec->pages[i];
+
+                if (PagePrivate(page) && !TestSetPageLocked(page)) {
+                        try_to_release_page(page, 0);
+                        unlock_page(page);
+                }
+        }
+}
+
+/**
+ * pagevec_lookup - gang pagecache lookup
+ * @pvec:       Where the resulting pages are placed
+ * @mapping:    The address_space to search
+ * @start:      The starting page index
+ * @nr_pages:   The maximum number of pages
+ *
+ * pagevec_lookup() will search for and return a group of up to @nr_pages pages
+ * in the mapping.  The pages are placed in @pvec.  pagevec_lookup() takes a
+ * reference against the pages in @pvec.
+ *
+ * The search returns a group of mapping-contiguous pages with ascending
+ * indexes.  There may be holes in the indices due to not-present pages.
+ *
+ * pagevec_lookup() returns the number of pages which were found.
+ */
+unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
+                pgoff_t start, unsigned nr_pages)
+{
+        pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
+        return pagevec_count(pvec);
+}
+
+unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
+                pgoff_t *index, int tag, unsigned nr_pages)
+{
+        pvec->nr = find_get_pages_tag(mapping, index, tag,
+                                        nr_pages, pvec->pages);
+        return pagevec_count(pvec);
+}
+
+
+#ifdef CONFIG_SMP
+/*
+ * We tolerate a little inaccuracy to avoid ping-ponging the counter between
+ * CPUs
+ */
+#define ACCT_THRESHOLD  max(16, NR_CPUS * 2)
+
+static DEFINE_PER_CPU(long, committed_space) = 0;
+
+void vm_acct_memory(long pages)
+{
+        long *local;
+
+        preempt_disable();
+        local = &__get_cpu_var(committed_space);
+        *local += pages;
+        if (*local > ACCT_THRESHOLD || *local < -ACCT_THRESHOLD) {
+                atomic_add(*local, &vm_committed_space);
+                *local = 0;
+        }
+        preempt_enable();
+}
+EXPORT_SYMBOL(vm_acct_memory);
+
+#ifdef CONFIG_HOTPLUG_CPU
+static void lru_drain_cache(unsigned int cpu)
+{
+        struct pagevec *pvec = &per_cpu(lru_add_pvecs, cpu);
+
+        /* CPU is dead, so no locking needed. */
+        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);
+}
+
+/* Drop the CPU's cached committed space back into the central pool. */
+static int cpu_swap_callback(struct notifier_block *nfb,
+                             unsigned long action,
+                             void *hcpu)
+{
+        long *committed;
+
+        committed = &per_cpu(committed_space, (long)hcpu);
+        if (action == CPU_DEAD) {
+                atomic_add(*committed, &vm_committed_space);
+                *committed = 0;
+                lru_drain_cache((long)hcpu);
+        }
+        return NOTIFY_OK;
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+#endif /* CONFIG_SMP */
+
+#ifdef CONFIG_SMP
+void percpu_counter_mod(struct percpu_counter *fbc, long amount)
+{
+        long count;
+        long *pcount;
+        int cpu = get_cpu();
+
+        pcount = per_cpu_ptr(fbc->counters, cpu);
+        count = *pcount + amount;
+        if (count >= FBC_BATCH || count <= -FBC_BATCH) {
+                spin_lock(&fbc->lock);
+                fbc->count += count;
+                spin_unlock(&fbc->lock);
+                count = 0;
+        }
+        *pcount = count;
+        put_cpu();
+}
+EXPORT_SYMBOL(percpu_counter_mod);
+#endif
+
+/*
+ * Perform any setup for the swap system
+ */
+void __init swap_setup(void)
+{
+        unsigned long megs = num_physpages >> (20 - PAGE_SHIFT);
+
+        /* Use a smaller cluster for small-memory machines */
+        if (megs < 16)
+                page_cluster = 2;
+        else
+                page_cluster = 3;
+        /*
+         * Right now other parts of the system means that we
+         * _really_ don't want to cluster much more
+         */
+        hotcpu_notifier(cpu_swap_callback, 0);
+}