mm/swap: convert lru_add to a folio_batch

When adding folios to the LRU for the first time, the LRU flag will
already be clear, so skip the test-and-clear part of moving from one
LRU to another.

Removes 285 bytes from kernel text, mostly due to removing
__pagevec_lru_add().

Link: https://lkml.kernel.org/r/20220617175020.717127-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/swap.c b/mm/swap.c
index cab77a5..cb7669b 100644 (file)
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -61,7 +61,7 @@ static DEFINE_PER_CPU(struct lru_rotate, lru_rotate) = {
  */
 struct lru_pvecs {
        local_lock_t lock;
-       struct pagevec lru_add;
+       struct folio_batch lru_add;
        struct pagevec lru_deactivate_file;
        struct pagevec lru_deactivate;
        struct pagevec lru_lazyfree;
@@ -228,14 +228,13 @@ static bool pagevec_add_and_need_flush(struct pagevec *pvec, struct page *page)
 
 typedef void (*move_fn_t)(struct lruvec *lruvec, struct folio *folio);
 
-static void __pagevec_lru_add_fn(struct folio *folio, struct lruvec *lruvec)
+static void lru_add_fn(struct lruvec *lruvec, struct folio *folio)
 {
        int was_unevictable = folio_test_clear_unevictable(folio);
        long nr_pages = folio_nr_pages(folio);
 
        VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
 
-       folio_set_lru(folio);
        /*
         * Is an smp_mb__after_atomic() still required here, before
         * folio_evictable() tests PageMlocked, to rule out the possibility
@@ -269,28 +268,6 @@ static void __pagevec_lru_add_fn(struct folio *folio, struct lruvec *lruvec)
        trace_mm_lru_insertion(folio);
 }
 
-/*
- * Add the passed pages to the LRU, then drop the caller's refcount
- * on them.  Reinitialises the caller's pagevec.
- */
-static void __pagevec_lru_add(struct pagevec *pvec)
-{
-       int i;
-       struct lruvec *lruvec = NULL;
-       unsigned long flags = 0;
-
-       for (i = 0; i < pagevec_count(pvec); i++) {
-               struct folio *folio = page_folio(pvec->pages[i]);
-
-               lruvec = folio_lruvec_relock_irqsave(folio, lruvec, &flags);
-               __pagevec_lru_add_fn(folio, lruvec);
-       }
-       if (lruvec)
-               unlock_page_lruvec_irqrestore(lruvec, flags);
-       release_pages(pvec->pages, pvec->nr);
-       pagevec_reinit(pvec);
-}
-
 static void folio_batch_move_lru(struct folio_batch *fbatch, move_fn_t move_fn)
 {
        int i;
@@ -301,7 +278,7 @@ static void folio_batch_move_lru(struct folio_batch *fbatch, move_fn_t move_fn)
                struct folio *folio = fbatch->folios[i];
 
                /* block memcg migration while the folio moves between lru */
-               if (!folio_test_clear_lru(folio))
+               if (move_fn != lru_add_fn && !folio_test_clear_lru(folio))
                        continue;
 
                lruvec = folio_lruvec_relock_irqsave(folio, lruvec, &flags);
@@ -473,26 +450,26 @@ static void folio_activate(struct folio *folio)
 
 static void __lru_cache_activate_folio(struct folio *folio)
 {
-       struct pagevec *pvec;
+       struct folio_batch *fbatch;
        int i;
 
        local_lock(&lru_pvecs.lock);
-       pvec = this_cpu_ptr(&lru_pvecs.lru_add);
+       fbatch = this_cpu_ptr(&lru_pvecs.lru_add);
 
        /*
-        * Search backwards on the optimistic assumption that the page being
-        * activated has just been added to this pagevec. Note that only
-        * the local pagevec is examined as a !PageLRU page could be in the
+        * Search backwards on the optimistic assumption that the folio being
+        * activated has just been added to this batch. Note that only
+        * the local batch is examined as a !LRU folio could be in the
         * process of being released, reclaimed, migrated or on a remote
-        * pagevec that is currently being drained. Furthermore, marking
-        * a remote pagevec's page PageActive potentially hits a race where
-        * a page is marked PageActive just after it is added to the inactive
+        * batch that is currently being drained. Furthermore, marking
+        * a remote batch's folio active potentially hits a race where
+        * a folio is marked active just after it is added to the inactive
         * list causing accounting errors and BUG_ON checks to trigger.
         */
-       for (i = pagevec_count(pvec) - 1; i >= 0; i--) {
-               struct page *pagevec_page = pvec->pages[i];
+       for (i = folio_batch_count(fbatch) - 1; i >= 0; i--) {
+               struct folio *batch_folio = fbatch->folios[i];
 
-               if (pagevec_page == &folio->page) {
+               if (batch_folio == folio) {
                        folio_set_active(folio);
                        break;
                }
@@ -551,16 +528,16 @@ EXPORT_SYMBOL(folio_mark_accessed);
  */
 void folio_add_lru(struct folio *folio)
 {
-       struct pagevec *pvec;
+       struct folio_batch *fbatch;
 
-       VM_BUG_ON_FOLIO(folio_test_active(folio) && folio_test_unevictable(folio), folio);
+       VM_BUG_ON_FOLIO(folio_test_active(folio) &&
+                       folio_test_unevictable(folio), folio);
        VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
 
        folio_get(folio);
        local_lock(&lru_pvecs.lock);
-       pvec = this_cpu_ptr(&lru_pvecs.lru_add);
-       if (pagevec_add_and_need_flush(pvec, &folio->page))
-               __pagevec_lru_add(pvec);
+       fbatch = this_cpu_ptr(&lru_pvecs.lru_add);
+       folio_batch_add_and_move(fbatch, folio, lru_add_fn);
        local_unlock(&lru_pvecs.lock);
 }
 EXPORT_SYMBOL(folio_add_lru);
@@ -691,11 +668,11 @@ static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec)
  */
 void lru_add_drain_cpu(int cpu)
 {
-       struct folio_batch *fbatch;
-       struct pagevec *pvec = &per_cpu(lru_pvecs.lru_add, cpu);
+       struct folio_batch *fbatch = &per_cpu(lru_pvecs.lru_add, cpu);
+       struct pagevec *pvec;
 
-       if (pagevec_count(pvec))
-               __pagevec_lru_add(pvec);
+       if (folio_batch_count(fbatch))
+               folio_batch_move_lru(fbatch, lru_add_fn);
 
        fbatch = &per_cpu(lru_rotate.fbatch, cpu);
        /* Disabling interrupts below acts as a compiler barrier. */
@@ -920,7 +897,7 @@ static inline void __lru_add_drain_all(bool force_all_cpus)
        for_each_online_cpu(cpu) {
                struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
 
-               if (pagevec_count(&per_cpu(lru_pvecs.lru_add, cpu)) ||
+               if (folio_batch_count(&per_cpu(lru_pvecs.lru_add, cpu)) ||
                    data_race(folio_batch_count(&per_cpu(lru_rotate.fbatch, cpu))) ||
                    pagevec_count(&per_cpu(lru_pvecs.lru_deactivate_file, cpu)) ||
                    pagevec_count(&per_cpu(lru_pvecs.lru_deactivate, cpu)) ||
@@ -1084,8 +1061,8 @@ EXPORT_SYMBOL(release_pages);
  * 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
+ * So __pagevec_release() will drain those queues here.
+ * folio_batch_move_lru() calls folios_put() directly to avoid
  * mutual recursion.
  */
 void __pagevec_release(struct pagevec *pvec)