mm, page_alloc: don't duplicate code in free_pcp_prepare

The new free_pcp_prepare() function shares a lot of code with
free_pages_prepare(), which makes this a maintenance risk when some
future patch modifies only one of them.  We should be able to achieve
the same effect (skipping free_pages_check() from !DEBUG_VM configs) by
adding a parameter to free_pages_prepare() and making it inline, so the
checks (and the order != 0 parts) are eliminated from the call from
free_pcp_prepare().

!DEBUG_VM: bloat-o-meter reports no difference, as my gcc was already
inlining free_pages_prepare() and the elimination seems to work as
expected

DEBUG_VM bloat-o-meter:

  add/remove: 0/1 grow/shrink: 2/0 up/down: 1035/-778 (257)
  function                                     old     new   delta
  __free_pages_ok                              297    1060    +763
  free_hot_cold_page                           480     752    +272
  free_pages_prepare                           778       -    -778

Here inlining didn't occur before, and added some code, but it's ok for
a debug option.

[akpm@linux-foundation.org: fix build]
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 55 insertions, 78 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 193ed34a2780..7d8f642c498d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -991,47 +991,77 @@ out:
         return ret;
 }
 
-static bool free_pages_prepare(struct page *page, unsigned int order);
-
-#ifdef CONFIG_DEBUG_VM
-static inline bool free_pcp_prepare(struct page *page)
+static __always_inline bool free_pages_prepare(struct page *page,
+                                        unsigned int order, bool check_free)
 {
-        return free_pages_prepare(page, 0);
-}
+        int bad = 0;
 
-static inline bool bulkfree_pcp_prepare(struct page *page)
-{
-        return false;
-}
-#else
-static bool free_pcp_prepare(struct page *page)
-{
         VM_BUG_ON_PAGE(PageTail(page), page);
 
-        trace_mm_page_free(page, 0);
-        kmemcheck_free_shadow(page, 0);
-        kasan_free_pages(page, 0);
+        trace_mm_page_free(page, order);
+        kmemcheck_free_shadow(page, order);
+        kasan_free_pages(page, order);
+
+        /*
+         * Check tail pages before head page information is cleared to
+         * avoid checking PageCompound for order-0 pages.
+         */
+        if (unlikely(order)) {
+                bool compound = PageCompound(page);
+                int i;
+
+                VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
 
+                for (i = 1; i < (1 << order); i++) {
+                        if (compound)
+                                bad += free_tail_pages_check(page, page + i);
+                        if (unlikely(free_pages_check(page + i))) {
+                                bad++;
+                                continue;
+                        }
+                        (page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+                }
+        }
         if (PageAnonHead(page))
                 page->mapping = NULL;
+        if (check_free)
+                bad += free_pages_check(page);
+        if (bad)
+                return false;
 
-        reset_page_owner(page, 0);
+        page_cpupid_reset_last(page);
+        page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+        reset_page_owner(page, order);
 
         if (!PageHighMem(page)) {
                 debug_check_no_locks_freed(page_address(page),
-                                           PAGE_SIZE);
+                                           PAGE_SIZE << order);
                 debug_check_no_obj_freed(page_address(page),
-                                           PAGE_SIZE);
+                                           PAGE_SIZE << order);
         }
-        arch_free_page(page, 0);
-        kernel_poison_pages(page, 0, 0);
-        kernel_map_pages(page, 0, 0);
+        arch_free_page(page, order);
+        kernel_poison_pages(page, 1 << order, 0);
+        kernel_map_pages(page, 1 << order, 0);
 
-        page_cpupid_reset_last(page);
-        page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
         return true;
 }
 
+#ifdef CONFIG_DEBUG_VM
+static inline bool free_pcp_prepare(struct page *page)
+{
+        return free_pages_prepare(page, 0, true);
+}
+
+static inline bool bulkfree_pcp_prepare(struct page *page)
+{
+        return false;
+}
+#else
+static bool free_pcp_prepare(struct page *page)
+{
+        return free_pages_prepare(page, 0, false);
+}
+
 static bool bulkfree_pcp_prepare(struct page *page)
 {
         return free_pages_check(page);
@@ -1201,66 +1231,13 @@ void __meminit reserve_bootmem_region(unsigned long start, unsigned long end)
         }
 }
 
-static bool free_pages_prepare(struct page *page, unsigned int order)
-{
-        int bad = 0;
-
-        VM_BUG_ON_PAGE(PageTail(page), page);
-
-        trace_mm_page_free(page, order);
-        kmemcheck_free_shadow(page, order);
-        kasan_free_pages(page, order);
-
-        /*
-         * Check tail pages before head page information is cleared to
-         * avoid checking PageCompound for order-0 pages.
-         */
-        if (unlikely(order)) {
-                bool compound = PageCompound(page);
-                int i;
-
-                VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
-
-                for (i = 1; i < (1 << order); i++) {
-                        if (compound)
-                                bad += free_tail_pages_check(page, page + i);
-                        if (unlikely(free_pages_check(page + i))) {
-                                bad++;
-                                continue;
-                        }
-                        (page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
-                }
-        }
-        if (PageAnonHead(page))
-                page->mapping = NULL;
-        bad += free_pages_check(page);
-        if (bad)
-                return false;
-
-        page_cpupid_reset_last(page);
-        page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
-        reset_page_owner(page, order);
-
-        if (!PageHighMem(page)) {
-                debug_check_no_locks_freed(page_address(page),
-                                           PAGE_SIZE << order);
-                debug_check_no_obj_freed(page_address(page),
-                                           PAGE_SIZE << order);
-        }
-        arch_free_page(page, order);
-        kernel_poison_pages(page, 1 << order, 0);
-        kernel_map_pages(page, 1 << order, 0);
-
-        return true;
-}
-
 static void __free_pages_ok(struct page *page, unsigned int order)
 {
         unsigned long flags;
         int migratetype;
         unsigned long pfn = page_to_pfn(page);
 
-        if (!free_pages_prepare(page, order))
+        if (!free_pages_prepare(page, order, true))
                 return;
 
         migratetype = get_pfnblock_migratetype(page, pfn);