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Date: Thu, 21 Mar 2024 09:36:45 -0700
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Subject: [PATCH v6 23/37] mm/slab: add allocation accounting into slab
 allocation and free paths
From: Suren Baghdasaryan <surenb@google.com>
To: akpm@linux-foundation.org
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Content-Type: text/plain; charset="UTF-8"

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>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
---
 mm/slub.c | 96 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 95 insertions(+), 1 deletion(-)

diff --git a/mm/slub.c b/mm/slub.c
index 666dcc3b8a26..5840ab963319 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1932,7 +1932,68 @@ static inline void free_slab_obj_exts(struct slab *slab)
 	kfree(obj_exts);
 	slab->obj_exts = 0;
 }
+
+static inline bool need_slab_obj_ext(void)
+{
+	if (mem_alloc_profiling_enabled())
+		return true;
+
+	/*
+	 * 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 (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);
+}
+
+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;
+
+	if (!mem_alloc_profiling_enabled())
+		return;
+
+	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);
+	}
+#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)
 {
@@ -1942,6 +2003,24 @@ static int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
 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;
+}
+
+static inline void
+alloc_tagging_slab_free_hook(struct kmem_cache *s, struct slab *slab, void **p,
+			     int objects)
+{
+}
+
 #endif /* CONFIG_SLAB_OBJ_EXT */
 
 #ifdef CONFIG_MEMCG_KMEM
@@ -2370,7 +2449,7 @@ static __always_inline void account_slab(struct slab *slab, int order,
 static __always_inline void unaccount_slab(struct slab *slab, int order,
 					   struct kmem_cache *s)
 {
-	if (memcg_kmem_online())
+	if (memcg_kmem_online() || need_slab_obj_ext())
 		free_slab_obj_exts(slab);
 
 	mod_node_page_state(slab_pgdat(slab), cache_vmstat_idx(s),
@@ -3823,6 +3902,7 @@ 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;
@@ -3865,6 +3945,18 @@ 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);
+		if (need_slab_obj_ext()) {
+			obj_exts = prepare_slab_obj_exts_hook(s, flags, p[i]);
+#ifdef CONFIG_MEM_ALLOC_PROFILING
+			/*
+			 * 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
+		}
 	}
 
 	memcg_slab_post_alloc_hook(s, objcg, flags, size, p);
@@ -4339,6 +4431,7 @@ 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);
@@ -4349,6 +4442,7 @@ 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.
-- 
2.44.0.291.gc1ea87d7ee-goog