diff options
| author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2023-01-11 14:29:02 +0000 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-02-02 22:32:58 -0800 |
| commit | 5eb5cea11dcbafaa37685bc4e89e1d4ae9c434ea (patch) | |
| tree | a1c5833b70e2c14731c73f085b6fb8a3a89586e9 /include | |
| parent | 1aa4d03b60c0f61a8d96d5d633bf7968dbf6841f (diff) | |
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: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/mm.h | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 7ff6e2410aa3..3adc37cebe6f 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -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; } /** |