Commit 5eb5cea1 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

mm: reimplement compound_order() 

Make compound_order() use struct folio.  It can't be turned into a wrapper
around folio_order() as a page can be turned into a tail page between a
check in compound_order() and the assertion in folio_test_large().

Link: https://lkml.kernel.org/r/20230111142915.1001531-17-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 1aa4d03b

include/linux/mm.h

+11 −2
Original line number Diff line number Diff line
@@ -719,11 +719,20 @@ int vma_is_stack_for_current(struct vm_area_struct *vma); 
struct mmu_gather;

struct inode;



/*

 * compound_order() can be called without holding a reference, which means

 * that niceties like page_folio() don't work.  These callers should be

 * prepared to handle wild return values.  For example, PG_head may be

 * set before _folio_order is initialised, or this may be a tail page.

 * See compaction.c for some good examples.

 */

static inline unsigned int compound_order(struct page *page)

{

	if (!PageHead(page))

	struct folio *folio = (struct folio *)page;



	if (!test_bit(PG_head, &folio->flags))

		return 0;

	return page[1].compound_order;

	return folio->_folio_order;

}



/**