From ff202303c398ed56386ca4954154de9a96eb732a Mon Sep 17 00:00:00 2001 From: Stephen Brennan Date: Fri, 7 Jun 2024 13:29:53 -0700 Subject: [PATCH] mm: convert page type macros to enum Changing PG_slab from a page flag to a page type in commit 46df8e73a4a3 ("mm: free up PG_slab") in has the unintended consequence of removing the PG_slab constant from kernel debuginfo. The commit does add the value to the vmcoreinfo note, which allows debuggers to find the value without hardcoding it. However it's most flexible to continue representing the constant with an enum. To that end, convert the page type fields into an enum. Debuggers will now be able to detect that PG_slab's type has changed from enum pageflags to enum pagetype. Link: https://lkml.kernel.org/r/20240607202954.1198180-1-stephen.s.brennan@oracle.com Fixes: 46df8e73a4a3 ("mm: free up PG_slab") Signed-off-by: Stephen Brennan Acked-by: Vlastimil Babka Cc: David Hildenbrand Cc: Hao Ge Cc: Matthew Wilcox (Oracle) Cc: Omar Sandoval Cc: Vishal Moola (Oracle) Signed-off-by: Andrew Morton --- include/linux/page-flags.h | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 104078afe0b1..b9e914e1face 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -944,15 +944,18 @@ PAGEFLAG_FALSE(HasHWPoisoned, has_hwpoisoned) * mistaken for a page type value. */ -#define PAGE_TYPE_BASE 0xf0000000 -/* Reserve 0x0000007f to catch underflows of _mapcount */ -#define PAGE_MAPCOUNT_RESERVE -128 -#define PG_buddy 0x00000080 -#define PG_offline 0x00000100 -#define PG_table 0x00000200 -#define PG_guard 0x00000400 -#define PG_hugetlb 0x00000800 -#define PG_slab 0x00001000 +enum pagetype { + PG_buddy = 0x00000080, + PG_offline = 0x00000100, + PG_table = 0x00000200, + PG_guard = 0x00000400, + PG_hugetlb = 0x00000800, + PG_slab = 0x00001000, + + PAGE_TYPE_BASE = 0xf0000000, + /* Reserve 0x0000007f to catch underflows of _mapcount */ + PAGE_MAPCOUNT_RESERVE = -128, +}; #define PageType(page, flag) \ ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)