[PATCH v4 22/36] mm/slab: add allocation accounting into slab allocation and free paths

[Suren Baghdasaryan <surenb@google.com>]

Account slab allocations using codetag reference embedded into slabobj_ext.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Co-developed-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
 mm/slab.h | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 mm/slub.c |  9 ++++++++
 2 files changed, 75 insertions(+)

diff --git a/mm/slab.h b/mm/slab.h
index 13b6ba2abd74..c4bd0d5348cb 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -567,6 +567,46 @@ static inline struct slabobj_ext *slab_obj_exts(struct slab *slab)
 int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
 			gfp_t gfp, bool new_slab);
 
+static inline bool need_slab_obj_ext(void)
+{
+#ifdef CONFIG_MEM_ALLOC_PROFILING
+	if (mem_alloc_profiling_enabled())
+		return true;
+#endif
+	/*
+	 * CONFIG_MEMCG_KMEM creates vector of obj_cgroup objects conditionally
+	 * inside memcg_slab_post_alloc_hook. No other users for now.
+	 */
+	return false;
+}
+
+static inline struct slabobj_ext *
+prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
+{
+	struct slab *slab;
+
+	if (!p)
+		return NULL;
+
+	if (!need_slab_obj_ext())
+		return NULL;
+
+	if (s->flags & SLAB_NO_OBJ_EXT)
+		return NULL;
+
+	if (flags & __GFP_NO_OBJ_EXT)
+		return NULL;
+
+	slab = virt_to_slab(p);
+	if (!slab_obj_exts(slab) &&
+	    WARN(alloc_slab_obj_exts(slab, s, flags, false),
+		 "%s, %s: Failed to create slab extension vector!\n",
+		 __func__, s->name))
+		return NULL;
+
+	return slab_obj_exts(slab) + obj_to_index(s, slab, p);
+}
+
 #else /* CONFIG_SLAB_OBJ_EXT */
 
 static inline struct slabobj_ext *slab_obj_exts(struct slab *slab)
@@ -589,6 +629,32 @@ prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
 
 #endif /* CONFIG_SLAB_OBJ_EXT */
 
+#ifdef CONFIG_MEM_ALLOC_PROFILING
+
+static inline void alloc_tagging_slab_free_hook(struct kmem_cache *s, struct slab *slab,
+					void **p, int objects)
+{
+	struct slabobj_ext *obj_exts;
+	int i;
+
+	obj_exts = slab_obj_exts(slab);
+	if (!obj_exts)
+		return;
+
+	for (i = 0; i < objects; i++) {
+		unsigned int off = obj_to_index(s, slab, p[i]);
+
+		alloc_tag_sub(&obj_exts[off].ref, s->size);
+	}
+}
+
+#else
+
+static inline void alloc_tagging_slab_free_hook(struct kmem_cache *s, struct slab *slab,
+					void **p, int objects) {}
+
+#endif /* CONFIG_MEM_ALLOC_PROFILING */
+
 #ifdef CONFIG_MEMCG_KMEM
 void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat,
 		     enum node_stat_item idx, int nr);
diff --git a/mm/slub.c b/mm/slub.c
index 5dc7beda6c0d..a69b6b4c8df6 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3826,6 +3826,7 @@ void slab_post_alloc_hook(struct kmem_cache *s,	struct obj_cgroup *objcg,
 			  unsigned int orig_size)
 {
 	unsigned int zero_size = s->object_size;
+	struct slabobj_ext *obj_exts;
 	bool kasan_init = init;
 	size_t i;
 	gfp_t init_flags = flags & gfp_allowed_mask;
@@ -3868,6 +3869,12 @@ void slab_post_alloc_hook(struct kmem_cache *s,	struct obj_cgroup *objcg,
 		kmemleak_alloc_recursive(p[i], s->object_size, 1,
 					 s->flags, init_flags);
 		kmsan_slab_alloc(s, p[i], init_flags);
+		obj_exts = prepare_slab_obj_exts_hook(s, flags, p[i]);
+#ifdef CONFIG_MEM_ALLOC_PROFILING
+		/* obj_exts can be allocated for other reasons */
+		if (likely(obj_exts) && mem_alloc_profiling_enabled())
+			alloc_tag_add(&obj_exts->ref, current->alloc_tag, s->size);
+#endif
 	}
 
 	memcg_slab_post_alloc_hook(s, objcg, flags, size, p);
@@ -4346,6 +4353,7 @@ void slab_free(struct kmem_cache *s, struct slab *slab, void *object,
 	       unsigned long addr)
 {
 	memcg_slab_free_hook(s, slab, &object, 1);
+	alloc_tagging_slab_free_hook(s, slab, &object, 1);
 
 	if (likely(slab_free_hook(s, object, slab_want_init_on_free(s))))
 		do_slab_free(s, slab, object, object, 1, addr);
@@ -4356,6 +4364,7 @@ void slab_free_bulk(struct kmem_cache *s, struct slab *slab, void *head,
 		    void *tail, void **p, int cnt, unsigned long addr)
 {
 	memcg_slab_free_hook(s, slab, p, cnt);
+	alloc_tagging_slab_free_hook(s, slab, p, cnt);
 	/*
 	 * With KASAN enabled slab_free_freelist_hook modifies the freelist
 	 * to remove objects, whose reuse must be delayed.
-- 
2.44.0.rc0.258.g7320e95886-goog