linux-kernel - [PATCH v3 1/2] alloc_tag: introduce clear_page_tag

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Message-ID: <20240813150758.855881-1-surenb@google.com>
Date: Tue, 13 Aug 2024 08:07:56 -0700
From: Suren Baghdasaryan <surenb@...gle.com>
To: akpm@...ux-foundation.org
Cc: kent.overstreet@...ux.dev, david@...hat.com, vbabka@...e.cz, 
	pasha.tatashin@...een.com, souravpanda@...gle.com, keescook@...omium.org, 
	linux-kernel@...r.kernel.org, linux-mm@...ck.org, surenb@...gle.com, 
	stable@...r.kernel.org
Subject: [PATCH v3 1/2] alloc_tag: introduce clear_page_tag_ref() helper function

In several cases we are freeing pages which were not allocated using
common page allocators. For such cases, in order to keep allocation
accounting correct, we should clear the page tag to indicate that the
page being freed is expected to not have a valid allocation tag.
Introduce clear_page_tag_ref() helper function to be used for this.

Suggested-by: David Hildenbrand <david@...hat.com>
Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
Cc: stable@...r.kernel.org # v6.10
---
 include/linux/pgalloc_tag.h | 13 +++++++++++++
 mm/mm_init.c                | 10 +---------
 mm/page_alloc.c             |  9 +--------
 3 files changed, 15 insertions(+), 17 deletions(-)

diff --git a/include/linux/pgalloc_tag.h b/include/linux/pgalloc_tag.h
index 18cd0c0c73d9..207f0c83c8e9 100644
--- a/include/linux/pgalloc_tag.h
+++ b/include/linux/pgalloc_tag.h
@@ -43,6 +43,18 @@ static inline void put_page_tag_ref(union codetag_ref *ref)
 	page_ext_put(page_ext_from_codetag_ref(ref));
 }
 
+static inline void clear_page_tag_ref(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);
+		}
+	}
+}
+
 static inline void pgalloc_tag_add(struct page *page, struct task_struct *task,
 				   unsigned int nr)
 {
@@ -126,6 +138,7 @@ static inline void pgalloc_tag_sub_pages(struct alloc_tag *tag, unsigned int nr)
 
 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 clear_page_tag_ref(struct page *page) {}
 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 75c3bd42799b..907c46b0773f 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -2460,15 +2460,7 @@ void __init memblock_free_pages(struct page *page, unsigned long pfn,
 	}
 
 	/* 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);
-		}
-	}
-
+	clear_page_tag_ref(page);
 	__free_pages_core(page, order, MEMINIT_EARLY);
 }
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 28f80daf5c04..3f80e94a0b66 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5821,14 +5821,7 @@ unsigned long free_reserved_area(void *start, void *end, int poison, const char
 
 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);
-		}
-	}
+	clear_page_tag_ref(page);
 	ClearPageReserved(page);
 	init_page_count(page);
 	__free_page(page);

base-commit: d74da846046aeec9333e802f5918bd3261fb5509
-- 
2.46.0.76.ge559c4bf1a-goog