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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: 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>
This commit is contained in:
Kirill A. Shutemov 2015-02-11 15:25:50 -08:00 committed by Linus Torvalds
parent 05891fb065
commit 6e9f0d582d
1 changed files with 1 additions and 34 deletions
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35
mm/page_alloc.c
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@ -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)) {