mm/compaction: split freepages without holding the zone lock

We don't need to split freepages with holding the zone lock.  It will
cause more contention on zone lock so not desirable.

[rientjes@google.com: if __isolate_free_page() fails, avoid adding to freelist so we don't call map_pages() with it]
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1606211447001.43430@chino.kir.corp.google.com
Link: http://lkml.kernel.org/r/1464230275-25791-1-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 3e22335..6c9a394 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -537,7 +537,6 @@ void __put_page(struct page *page);
 void put_pages_list(struct list_head *pages);
 
 void split_page(struct page *page, unsigned int order);
-int split_free_page(struct page *page);
 
 /*
  * Compound pages have a destructor function.  Provide a

diff --git a/mm/compaction.c b/mm/compaction.c
index 6095055..3cda954 100644 (file)
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -64,13 +64,31 @@ static unsigned long release_freepages(struct list_head *freelist)
 
 static void map_pages(struct list_head *list)
 {
-       struct page *page;
+       unsigned int i, order, nr_pages;
+       struct page *page, *next;
+       LIST_HEAD(tmp_list);
+
+       list_for_each_entry_safe(page, next, list, lru) {
+               list_del(&page->lru);
 
-       list_for_each_entry(page, list, lru) {
-               arch_alloc_page(page, 0);
-               kernel_map_pages(page, 1, 1);
-               kasan_alloc_pages(page, 0);
+               order = page_private(page);
+               nr_pages = 1 << order;
+               set_page_private(page, 0);
+               set_page_refcounted(page);
+
+               arch_alloc_page(page, order);
+               kernel_map_pages(page, nr_pages, 1);
+               kasan_alloc_pages(page, order);
+               if (order)
+                       split_page(page, order);
+
+               for (i = 0; i < nr_pages; i++) {
+                       list_add(&page->lru, &tmp_list);
+                       page++;
+               }
        }
+
+       list_splice(&tmp_list, list);
 }
 
 static inline bool migrate_async_suitable(int migratetype)
@@ -405,12 +423,13 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
        unsigned long flags = 0;
        bool locked = false;
        unsigned long blockpfn = *start_pfn;
+       unsigned int order;
 
        cursor = pfn_to_page(blockpfn);
 
        /* Isolate free pages. */
        for (; blockpfn < end_pfn; blockpfn++, cursor++) {
-               int isolated, i;
+               int isolated;
                struct page *page = cursor;
 
                /*
@@ -476,17 +495,17 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
                                goto isolate_fail;
                }
 
-               /* Found a free page, break it into order-0 pages */
-               isolated = split_free_page(page);
+               /* Found a free page, will break it into order-0 pages */
+               order = page_order(page);
+               isolated = __isolate_free_page(page, order);
                if (!isolated)
                        break;
+               set_page_private(page, order);
 
                total_isolated += isolated;
                cc->nr_freepages += isolated;
-               for (i = 0; i < isolated; i++) {
-                       list_add(&page->lru, freelist);
-                       page++;
-               }
+               list_add_tail(&page->lru, freelist);
+
                if (!strict && cc->nr_migratepages <= cc->nr_freepages) {
                        blockpfn += isolated;
                        break;
@@ -605,7 +624,7 @@ isolate_freepages_range(struct compact_control *cc,
                 */
        }
 
-       /* split_free_page does not map the pages */
+       /* __isolate_free_page() does not map the pages */
        map_pages(&freelist);
 
        if (pfn < end_pfn) {
@@ -1102,7 +1121,7 @@ static void isolate_freepages(struct compact_control *cc)
                }
        }
 
-       /* split_free_page does not map the pages */
+       /* __isolate_free_page() does not map the pages */
        map_pages(freelist);
 
        /*

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8b26236..44cee1e 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2526,33 +2526,6 @@ int __isolate_free_page(struct page *page, unsigned int order)
        return 1UL << order;
 }
 
-/*
- * Similar to split_page except the page is already free. As this is only
- * being used for migration, the migratetype of the block also changes.
- * As this is called with interrupts disabled, the caller is responsible
- * for calling arch_alloc_page() and kernel_map_page() after interrupts
- * are enabled.
- *
- * Note: this is probably too low level an operation for use in drivers.
- * Please consult with lkml before using this in your driver.
- */
-int split_free_page(struct page *page)
-{
-       unsigned int order;
-       int nr_pages;
-
-       order = page_order(page);
-
-       nr_pages = __isolate_free_page(page, order);
-       if (!nr_pages)
-               return 0;
-
-       /* Split into individual pages */
-       set_page_refcounted(page);
-       split_page(page, order);
-       return nr_pages;
-}
-
 /*
  * Update NUMA hit/miss statistics
  *