mm/page_alloc.c: drop dead destroy_compound_page() (6e9f0d58) · Commits · 戴 / test

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:

Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

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)) {

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