[PATCH RFC v2 06/27] mm: page_alloc: Allow an arch to hook early into free_pages_prepare()

[Alexandru Elisei]

Add arch_free_pages_prepare() hook that is called before that page flags
are cleared. This will be used by arm64 when explicit management of tag
storage pages is enabled.

Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
---
 include/linux/pgtable.h | 4 ++++
 mm/page_alloc.c         | 4 +++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index b31f53e9ab1d..3f34f00ced62 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -880,6 +880,10 @@ static inline int arch_prep_new_page(struct page *page, int order, gfp_t gfp)
 }
 #endif
 
+#ifndef __HAVE_ARCH_FREE_PAGES_PREPARE
+static inline void arch_free_pages_prepare(struct page *page, int order) { }
+#endif
+
 #ifndef __HAVE_ARCH_UNMAP_ONE
 /*
  * Some architectures support metadata associated with a page. When a
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b2782b778e78..86e4b1dac538 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1086,6 +1086,8 @@ static __always_inline bool free_pages_prepare(struct page *page,
 	trace_mm_page_free(page, order);
 	kmsan_free_page(page, order);
 
+	arch_free_pages_prepare(page, order);
+
 	if (unlikely(PageHWPoison(page)) && !order) {
 		/*
 		 * Do not let hwpoison pages hit pcplists/buddy
@@ -3171,7 +3173,7 @@ static inline unsigned int gfp_to_alloc_flags_cma(gfp_t gfp_mask,
 	return alloc_flags;
 }
 
-#ifdef HAVE_ARCH_ALLOC_PAGE
+#ifdef HAVE_ARCH_PREP_NEW_PAGE
 static void return_page_to_buddy(struct page *page, int order)
 {
 	int migratetype = get_pfnblock_migratetype(page, pfn);
-- 
2.42.1