Commit e2769dbd authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds
Browse files

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: default avatarVlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarMel Gorman <mgorman@techsingularity.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 479f854a

mm/page_alloc.c

+55 −78
Original line number Diff line number Diff line
@@ -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);

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