diff options
| author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2023-08-16 16:11:58 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-08-21 14:28:45 -0700 |
| commit | ebc1baf5c9b46c2240c580a2fd992b2e48606dfa (patch) | |
| tree | c85f3ec8285498ef68bc6f63cdf63825647391d4 /include/linux/page-flags.h | |
| parent | c704ae9797843402436190a6f094a035237fd012 (diff) | |
mm: free up a word in the first tail page
Store the folio order in the low byte of the flags word in the first tail
page. This frees up the word that was being used to store the order and
dtor bytes previously.
Link: https://lkml.kernel.org/r/20230816151201.3655946-11-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Yanteng Si <siyanteng@loongson.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/linux/page-flags.h')
| -rw-r--r-- | include/linux/page-flags.h | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 46fc05c648ff..638b0a96b4c5 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -184,7 +184,8 @@ enum pageflags { /* * Flags only valid for compound pages. Stored in first tail page's - * flags word. + * flags word. Cannot use the first 8 flags or any flag marked as + * PF_ANY. */ /* At least one page in this folio has the hwpoison flag set */ @@ -1081,8 +1082,8 @@ static __always_inline void __ClearPageAnonExclusive(struct page *page) * the CHECK_AT_FREE flags above, so need to be cleared. */ #define PAGE_FLAGS_SECOND \ - (1UL << PG_has_hwpoisoned | 1UL << PG_hugetlb | \ - 1UL << PG_large_rmappable) + (0xffUL /* order */ | 1UL << PG_has_hwpoisoned | \ + 1UL << PG_hugetlb | 1UL << PG_large_rmappable) #define PAGE_FLAGS_PRIVATE \ (1UL << PG_private | 1UL << PG_private_2) |