+ mm-make-is_free_buddy_page-take-a-const-argument.patch added to mm-unstable branch

+ mm-make-is_free_buddy_page-take-a-const-argument.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: make is_free_buddy_page() take a const argument
has been added to the -mm mm-unstable branch.  Its filename is
     mm-make-is_free_buddy_page-take-a-const-argument.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-make-is_free_buddy_page-take-a-const-argument.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: mm: make is_free_buddy_page() take a const argument
Date: Tue, 26 Mar 2024 17:10:27 +0000

This function does not modify its argument; let the callers know that so
they can make better optimisation decisions.

Link: https://lkml.kernel.org/r/20240326171045.410737-6-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/page-flags.h |    2 +-
 mm/page_alloc.c            |    8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

--- a/include/linux/page-flags.h~mm-make-is_free_buddy_page-take-a-const-argument
+++ a/include/linux/page-flags.h
@@ -1088,7 +1088,7 @@ static inline bool is_page_hwpoison(cons
 	return folio_test_hugetlb(folio) && PageHWPoison(&folio->page);
 }
 
-extern bool is_free_buddy_page(struct page *page);
+bool is_free_buddy_page(const struct page *page);
 
 PAGEFLAG(Isolated, isolated, PF_ANY);
 
--- a/mm/page_alloc.c~mm-make-is_free_buddy_page-take-a-const-argument
+++ a/mm/page_alloc.c
@@ -6750,16 +6750,16 @@ void __offline_isolated_pages(unsigned l
 /*
  * This function returns a stable result only if called under zone lock.
  */
-bool is_free_buddy_page(struct page *page)
+bool is_free_buddy_page(const struct page *page)
 {
 	unsigned long pfn = page_to_pfn(page);
 	unsigned int order;
 
 	for (order = 0; order < NR_PAGE_ORDERS; order++) {
-		struct page *page_head = page - (pfn & ((1 << order) - 1));
+		const struct page *head = page - (pfn & ((1 << order) - 1));
 
-		if (PageBuddy(page_head) &&
-		    buddy_order_unsafe(page_head) >= order)
+		if (PageBuddy(head) &&
+		    buddy_order_unsafe(head) >= order)
 			break;
 	}
 
_

Patches currently in -mm which might be from willy@infradead.org are

mm-always-initialise-folio-_deferred_list.patch
mm-create-folio_flag_false-and-folio_type_ops-macros.patch
mm-remove-folio_prep_large_rmappable.patch
mm-support-page_mapcount-on-page_has_type-pages.patch
mm-turn-folio_test_hugetlb-into-a-pagetype.patch
mm-turn-folio_test_hugetlb-into-a-pagetype-fix.patch
mm-remove-a-call-to-compound_head-from-is_page_hwpoison.patch
mm-free-up-pg_slab.patch
mm-free-up-pg_slab-fix.patch
mm-improve-dumping-of-mapcount-and-page_type.patch
hugetlb-remove-mention-of-destructors.patch
sh-remove-use-of-pg_arch_1-on-individual-pages.patch
xtensa-remove-uses-of-pg_arch_1-on-individual-pages.patch
mm-make-page_ext_get-take-a-const-argument.patch
mm-make-folio_test_idle-and-folio_test_young-take-a-const-argument.patch
mm-make-is_free_buddy_page-take-a-const-argument.patch
mm-make-page_mapped-take-a-const-argument.patch
mm-convert-arch_clear_hugepage_flags-to-take-a-folio.patch
slub-remove-use-of-page-flags.patch
remove-references-to-page-flags-in-documentation.patch
proc-rewrite-stable_page_flags.patch