[PATCH v2 1/1] mm, slab: move allocation tagging code in the alloc path into a hook

[Suren Baghdasaryan <surenb@google.com>]

Move allocation tagging specific code in the allocation path into
alloc_tagging_slab_alloc_hook, similar to how freeing path uses
alloc_tagging_slab_free_hook. No functional changes, just code
cleanup.

Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
Changes since v1 [1]
- Moved entire profiling code portion from the slab_post_alloc_hook into
alloc_tagging_slab_alloc_hook, per Vlastimil Babka
- Moved alloc_tagging_slab_free_hook out of CONFIG_SLAB_OBJ_EXT section
and into CONFIG_MEM_ALLOC_PROFILING one, per Vlastimil Babka

[1] https://lore.kernel.org/all/20240703015354.3370503-1-surenb@google.com/

 mm/slub.c | 86 ++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 50 insertions(+), 36 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 4927edec6a8c..98c47ad7ceba 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2033,11 +2033,54 @@ prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
 	return slab_obj_exts(slab) + obj_to_index(s, slab, p);
 }
 
+#else /* CONFIG_SLAB_OBJ_EXT */
+
+static int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
+			       gfp_t gfp, bool new_slab)
+{
+	return 0;
+}
+
+static inline void free_slab_obj_exts(struct slab *slab)
+{
+}
+
+static inline bool need_slab_obj_ext(void)
+{
+	return false;
+}
+
+static inline struct slabobj_ext *
+prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
+{
+	return NULL;
+}
+
+#endif /* CONFIG_SLAB_OBJ_EXT */
+
+#ifdef CONFIG_MEM_ALLOC_PROFILING
+
+static inline void
+alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags)
+{
+	if (need_slab_obj_ext()) {
+		struct slabobj_ext *obj_exts;
+
+		obj_exts = prepare_slab_obj_exts_hook(s, flags, object);
+		/*
+		 * Currently obj_exts is used only for allocation profiling.
+		 * If other users appear then mem_alloc_profiling_enabled()
+		 * check should be added before alloc_tag_add().
+		 */
+		if (likely(obj_exts))
+			alloc_tag_add(&obj_exts->ref, current->alloc_tag, s->size);
+	}
+}
+
 static inline void
 alloc_tagging_slab_free_hook(struct kmem_cache *s, struct slab *slab, void **p,
 			     int objects)
 {
-#ifdef CONFIG_MEM_ALLOC_PROFILING
 	struct slabobj_ext *obj_exts;
 	int i;
 
@@ -2053,30 +2096,13 @@ alloc_tagging_slab_free_hook(struct kmem_cache *s, struct slab *slab, void **p,
 
 		alloc_tag_sub(&obj_exts[off].ref, s->size);
 	}
-#endif
-}
-
-#else /* CONFIG_SLAB_OBJ_EXT */
-
-static int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
-			       gfp_t gfp, bool new_slab)
-{
-	return 0;
-}
-
-static inline void free_slab_obj_exts(struct slab *slab)
-{
 }
 
-static inline bool need_slab_obj_ext(void)
-{
-	return false;
-}
+#else /* CONFIG_MEM_ALLOC_PROFILING */
 
-static inline struct slabobj_ext *
-prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
+static inline void
+alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags)
 {
-	return NULL;
 }
 
 static inline void
@@ -2085,7 +2111,8 @@ alloc_tagging_slab_free_hook(struct kmem_cache *s, struct slab *slab, void **p,
 {
 }
 
-#endif /* CONFIG_SLAB_OBJ_EXT */
+#endif /* CONFIG_MEM_ALLOC_PROFILING */
+
 
 #ifdef CONFIG_MEMCG_KMEM
 
@@ -3944,20 +3971,7 @@ bool slab_post_alloc_hook(struct kmem_cache *s, struct list_lru *lru,
 		kmemleak_alloc_recursive(p[i], s->object_size, 1,
 					 s->flags, init_flags);
 		kmsan_slab_alloc(s, p[i], init_flags);
-#ifdef CONFIG_MEM_ALLOC_PROFILING
-		if (need_slab_obj_ext()) {
-			struct slabobj_ext *obj_exts;
-
-			obj_exts = prepare_slab_obj_exts_hook(s, flags, p[i]);
-			/*
-			 * Currently obj_exts is used only for allocation profiling.
-			 * If other users appear then mem_alloc_profiling_enabled()
-			 * check should be added before alloc_tag_add().
-			 */
-			if (likely(obj_exts))
-				alloc_tag_add(&obj_exts->ref, current->alloc_tag, s->size);
-		}
-#endif
+		alloc_tagging_slab_alloc_hook(s, p[i], flags);
 	}
 
 	return memcg_slab_post_alloc_hook(s, lru, flags, size, p);

base-commit: 795c58e4c7fc6163d8fb9f2baa86cfe898fa4b19
-- 
2.45.2.803.g4e1b14247a-goog