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>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d664eb9..12d55b8 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -381,36 +381,6 @@
}
}
-/* 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 @@
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)) {