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.
[[email protected]: fix build]
Signed-off-by: Vlastimil Babka <[email protected]>
Signed-off-by: Mel Gorman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 193ed34..7d8f642 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -991,12 +991,65 @@
return ret;
}
-static bool free_pages_prepare(struct page *page, unsigned int order);
+static __always_inline bool free_pages_prepare(struct page *page,
+ unsigned int order, bool check_free)
+{
+ 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;
+ if (check_free)
+ 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;
+}
#ifdef CONFIG_DEBUG_VM
static inline bool free_pcp_prepare(struct page *page)
{
- return free_pages_prepare(page, 0);
+ return free_pages_prepare(page, 0, true);
}
static inline bool bulkfree_pcp_prepare(struct page *page)
@@ -1006,30 +1059,7 @@
#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);
-
- if (PageAnonHead(page))
- page->mapping = NULL;
-
- reset_page_owner(page, 0);
-
- if (!PageHighMem(page)) {
- debug_check_no_locks_freed(page_address(page),
- PAGE_SIZE);
- debug_check_no_obj_freed(page_address(page),
- PAGE_SIZE);
- }
- arch_free_page(page, 0);
- kernel_poison_pages(page, 0, 0);
- kernel_map_pages(page, 0, 0);
-
- page_cpupid_reset_last(page);
- page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
- return true;
+ return free_pages_prepare(page, 0, false);
}
static bool bulkfree_pcp_prepare(struct page *page)
@@ -1201,66 +1231,13 @@
}
}
-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);
