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

Suren Baghdasaryan
2024-02-21T19:41:45Z

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