[PATCH v6 23/37] mm/slab: add allocation accounting into slab allocation and free paths

Suren Baghdasaryan
2024-03-21T16:38:00Z

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