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Commit 6e9f0d58 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
Browse files

mm/page_alloc.c: drop dead destroy_compound_page() 



The only caller is __free_one_page(). By the time we should have
page->flags to be cleared already:

 - for 0-order pages though PCP list:
	free_hot_cold_page()
		free_pages_prepare()
			free_pages_check()
				page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
		<put the page to PCP list>

	free_pcppages_bulk()
		page = <withdraw pages from PCP list>
		__free_one_page(page)

 - for non-0-order pages:
	__free_pages_ok()
		free_pages_prepare()
			free_pages_check()
				page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
		free_one_page()
			__free_one_page()

So there's no way PageCompound() will return true in __free_one_page().
Let's remove dead destroy_compound_page() and put assert for page->flags
there instead.

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 05891fb0

mm/page_alloc.c

+1 −34
Original line number Diff line number Diff line
@@ -381,36 +381,6 @@ void prep_compound_page(struct page *page, unsigned long order) 
	}

}



/* update __split_huge_page_refcount if you change this function */

static int destroy_compound_page(struct page *page, unsigned long order)

{

	int i;

	int nr_pages = 1 << order;

	int bad = 0;



	if (unlikely(compound_order(page) != order)) {

		bad_page(page, "wrong compound order", 0);

		bad++;

	}



	__ClearPageHead(page);



	for (i = 1; i < nr_pages; i++) {

		struct page *p = page + i;



		if (unlikely(!PageTail(p))) {

			bad_page(page, "PageTail not set", 0);

			bad++;

		} else if (unlikely(p->first_page != page)) {

			bad_page(page, "first_page not consistent", 0);

			bad++;

		}

		__ClearPageTail(p);

	}



	return bad;

}



static inline void prep_zero_page(struct page *page, unsigned int order,

							gfp_t gfp_flags)

{
@@ -613,10 +583,7 @@ static inline void __free_one_page(struct page *page, 
	int max_order = MAX_ORDER;



	VM_BUG_ON(!zone_is_initialized(zone));



	if (unlikely(PageCompound(page)))

		if (unlikely(destroy_compound_page(page, order)))

			return;

	VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP, page);



	VM_BUG_ON(migratetype == -1);

	if (is_migrate_isolate(migratetype)) {