[PATCH v6 34/37] codetag: debug: mark codetags for reserved pages as empty

[Suren Baghdasaryan]

To avoid debug warnings while freeing reserved pages which were not
allocated with usual allocators, mark their codetags as empty before
freeing.

Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 include/linux/alloc_tag.h   |  1 +
 include/linux/mm.h          |  9 +++++++++
 include/linux/pgalloc_tag.h |  2 ++
 mm/mm_init.c                | 12 +++++++++++-
 4 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h
index c30e6c944353..100ddf66eb8e 100644
--- a/include/linux/alloc_tag.h
+++ b/include/linux/alloc_tag.h
@@ -46,6 +46,7 @@ static inline void set_codetag_empty(union codetag_ref *ref)
 #else /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
 
 static inline bool is_codetag_empty(union codetag_ref *ref) { return false; }
+static inline void set_codetag_empty(union codetag_ref *ref) {}
 
 #endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
 
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 8147b1302413..2615aa69c823 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -5,6 +5,7 @@
 #include <linux/errno.h>
 #include <linux/mmdebug.h>
 #include <linux/gfp.h>
+#include <linux/pgalloc_tag.h>
 #include <linux/bug.h>
 #include <linux/list.h>
 #include <linux/mmzone.h>
@@ -3132,6 +3133,14 @@ extern void reserve_bootmem_region(phys_addr_t start,
 /* Free the reserved page into the buddy system, so it gets managed. */
 static inline void free_reserved_page(struct page *page)
 {
+	if (mem_alloc_profiling_enabled()) {
+		union codetag_ref *ref = get_page_tag_ref(page);
+
+		if (ref) {
+			set_codetag_empty(ref);
+			put_page_tag_ref(ref);
+		}
+	}
 	ClearPageReserved(page);
 	init_page_count(page);
 	__free_page(page);
diff --git a/include/linux/pgalloc_tag.h b/include/linux/pgalloc_tag.h
index 50d212330bbb..62d8dad74b37 100644
--- a/include/linux/pgalloc_tag.h
+++ b/include/linux/pgalloc_tag.h
@@ -120,6 +120,8 @@ static inline void pgalloc_tag_sub_pages(struct alloc_tag *tag, unsigned int nr)
 
 #else /* CONFIG_MEM_ALLOC_PROFILING */
 
+static inline union codetag_ref *get_page_tag_ref(struct page *page) { return NULL; }
+static inline void put_page_tag_ref(union codetag_ref *ref) {}
 static inline void pgalloc_tag_add(struct page *page, struct task_struct *task,
 				   unsigned int nr) {}
 static inline void pgalloc_tag_sub(struct page *page, unsigned int nr) {}
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 3e48afcd0faa..c7d6376a180c 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -2510,7 +2510,6 @@ void *__init alloc_large_system_hash(const char *tablename,
 void __init memblock_free_pages(struct page *page, unsigned long pfn,
 							unsigned int order)
 {
-
 	if (IS_ENABLED(CONFIG_DEFERRED_STRUCT_PAGE_INIT)) {
 		int nid = early_pfn_to_nid(pfn);
 
@@ -2522,6 +2521,17 @@ void __init memblock_free_pages(struct page *page, unsigned long pfn,
 		/* KMSAN will take care of these pages. */
 		return;
 	}
+
+	/* pages were reserved and not allocated */
+	if (mem_alloc_profiling_enabled()) {
+		union codetag_ref *ref = get_page_tag_ref(page);
+
+		if (ref) {
+			set_codetag_empty(ref);
+			put_page_tag_ref(ref);
+		}
+	}
+
 	__free_pages_core(page, order);
 }
 
-- 
2.44.0.291.gc1ea87d7ee-goog