From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Subject: 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@xxxxxxxxxxxxxxxxxxxx: fix build]
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 133 +++++++++++++++++++---------------------------
1 file changed, 55 insertions(+), 78 deletions(-)
diff -puN mm/page_alloc.c~mm-page_alloc-dont-duplicate-code-in-free_pcp_prepare mm/page_alloc.c
--- a/mm/page_alloc.c~mm-page_alloc-dont-duplicate-code-in-free_pcp_prepare
+++ a/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(un
}
}
-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);
_
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