diff options
| author | Muchun Song <songmuchun@bytedance.com> | 2021-09-07 19:55:55 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-09-08 11:50:23 -0700 |
| commit | fe3df441ef885a75a3eff5e151ead1a92266d222 (patch) | |
| tree | 9e1d1e5c4b1851cb9c825adef186380161b7638a | |
| parent | 5ef5f810199f421cb6455aa018fb8f21151b4a16 (diff) | |
mm: remove redundant compound_head() calling
There is a READ_ONCE() in the macro of compound_head(), which will prevent
compiler from optimizing the code when there are more than once calling of
it in a function. Remove the redundant calling of compound_head() from
page_to_index() and page_add_file_rmap() for better code generation.
Link: https://lkml.kernel.org/r/20210811101431.83940-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | include/linux/pagemap.h | 7 | ||||
| -rw-r--r-- | mm/rmap.c | 6 |
2 files changed, 7 insertions, 6 deletions
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index ed02aa522263..904e57db3a7d 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -521,18 +521,17 @@ static inline struct page *read_mapping_page(struct address_space *mapping, */ static inline pgoff_t page_to_index(struct page *page) { - pgoff_t pgoff; + struct page *head; if (likely(!PageTransTail(page))) return page->index; + head = compound_head(page); /* * We don't initialize ->index for tail pages: calculate based on * head page */ - pgoff = compound_head(page)->index; - pgoff += page - compound_head(page); - return pgoff; + return head->index + page - head; } extern pgoff_t hugetlb_basepage_index(struct page *page); diff --git a/mm/rmap.c b/mm/rmap.c index b9eb5c12f3fe..b2cebf35ffe7 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1230,11 +1230,13 @@ void page_add_file_rmap(struct page *page, bool compound) nr_pages); } else { if (PageTransCompound(page) && page_mapping(page)) { + struct page *head = compound_head(page); + VM_WARN_ON_ONCE(!PageLocked(page)); - SetPageDoubleMap(compound_head(page)); + SetPageDoubleMap(head); if (PageMlocked(page)) - clear_page_mlock(compound_head(page)); + clear_page_mlock(head); } if (!atomic_inc_and_test(&page->_mapcount)) goto out; |