[PATCH RFC 2/4] mm, slab: move slab_memcg hooks to mm/memcontrol.c

Vlastimil Babka
2024-03-01T17:07:12Z

The hooks make multiple calls to functions in mm/memcontrol.c, including
to th current_obj_cgroup() marked __always_inline. It might be faster to
make a single call to the hook in mm/memcontrol.c instead. The hooks
also don't use almost anything from mm/slub.c. obj_full_size() can move
with the hooks and cache_vmstat_idx() to the internal mm/slab.h

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
mm/memcontrol.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++
mm/slab.h | 10 ++++++
mm/slub.c | 100 --------------------------------------------------------
3 files changed, 100 insertions(+), 100 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e4c8735e7c85..37ee9356a26c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3575,6 +3575,96 @@ void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size)
refill_obj_stock(objcg, size, true);
}

+static inline size_t obj_full_size(struct kmem_cache *s)
+{
+ /*
+ * For each accounted object there is an extra space which is used
+ * to store obj_cgroup membership. Charge it too.
+ */
+ return s->size + sizeof(struct obj_cgroup *);
+}
+
+bool __memcg_slab_post_alloc_hook(struct kmem_cache *s, struct list_lru *lru,
+ gfp_t flags, size_t size, void **p)
+{
+ struct obj_cgroup *objcg;
+ struct slab *slab;
+ unsigned long off;
+ size_t i;
+
+ /*
+ * The obtained objcg pointer is safe to use within the current scope,
+ * defined by current task or set_active_memcg() pair.
+ * obj_cgroup_get() is used to get a permanent reference.
+ */
+ objcg = current_obj_cgroup();
+ if (!objcg)
+ return true;
+
+ /*
+ * slab_alloc_node() avoids the NULL check, so we might be called with a
+ * single NULL object. kmem_cache_alloc_bulk() aborts if it can't fill
+ * the whole requested size.
+ * return success as there's nothing to free back
+ */
+ if (unlikely(*p == NULL))
+ return true;
+
+ flags &= gfp_allowed_mask;
+
+ if (lru) {
+ int ret;
+ struct mem_cgroup *memcg;
+
+ memcg = get_mem_cgroup_from_objcg(objcg);
+ ret = memcg_list_lru_alloc(memcg, lru, flags);
+ css_put(&memcg->css);
+
+ if (ret)
+ return false;
+ }
+
+ if (obj_cgroup_charge(objcg, flags, size * obj_full_size(s)))
+ return false;
+
+ for (i = 0; i < size; i++) {
+ slab = virt_to_slab(p[i]);
+
+ if (!slab_objcgs(slab) &&
+ memcg_alloc_slab_cgroups(slab, s, flags, false)) {
+ obj_cgroup_uncharge(objcg, obj_full_size(s));
+ continue;
+ }
+
+ off = obj_to_index(s, slab, p[i]);
+ obj_cgroup_get(objcg);
+ slab_objcgs(slab)[off] = objcg;
+ mod_objcg_state(objcg, slab_pgdat(slab),
+ cache_vmstat_idx(s), obj_full_size(s));
+ }
+
+ return true;
+}
+
+void __memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab,
+ void **p, int objects, struct obj_cgroup **objcgs)
+{
+ for (int i = 0; i < objects; i++) {
+ struct obj_cgroup *objcg;
+ unsigned int off;
+
+ off = obj_to_index(s, slab, p[i]);
+ objcg = objcgs[off];
+ if (!objcg)
+ continue;
+
+ objcgs[off] = NULL;
+ obj_cgroup_uncharge(objcg, obj_full_size(s));
+ mod_objcg_state(objcg, slab_pgdat(slab), cache_vmstat_idx(s),
+ -obj_full_size(s));
+ obj_cgroup_put(objcg);
+ }
+}
#endif /* CONFIG_MEMCG_KMEM */

/*
diff --git a/mm/slab.h b/mm/slab.h
index 54deeb0428c6..3f170673fa55 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -541,6 +541,12 @@ static inline bool kmem_cache_debug_flags(struct kmem_cache *s, slab_flags_t fla
return false;
}

+static inline enum node_stat_item cache_vmstat_idx(struct kmem_cache *s)
+{
+ return (s->flags & SLAB_RECLAIM_ACCOUNT) ?
+ NR_SLAB_RECLAIMABLE_B : NR_SLAB_UNRECLAIMABLE_B;
+}
+
#ifdef CONFIG_MEMCG_KMEM
/*
* slab_objcgs - get the object cgroups vector associated with a slab
@@ -564,6 +570,10 @@ int memcg_alloc_slab_cgroups(struct slab *slab, struct kmem_cache *s,
gfp_t gfp, bool new_slab);
void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat,
enum node_stat_item idx, int nr);
+bool __memcg_slab_post_alloc_hook(struct kmem_cache *s, struct list_lru *lru,
+ gfp_t flags, size_t size, void **p);
+void __memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab,
+ void **p, int objects, struct obj_cgroup **objcgs);
#else /* CONFIG_MEMCG_KMEM */
static inline struct obj_cgroup **slab_objcgs(struct slab *slab)
{
diff --git a/mm/slub.c b/mm/slub.c
index 7022a1246bab..64da169d672a 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1875,12 +1875,6 @@ static bool freelist_corrupted(struct kmem_cache *s, struct slab *slab,
#endif
#endif /* CONFIG_SLUB_DEBUG */

-static inline enum node_stat_item cache_vmstat_idx(struct kmem_cache *s)
-{
- return (s->flags & SLAB_RECLAIM_ACCOUNT) ?
- NR_SLAB_RECLAIMABLE_B : NR_SLAB_UNRECLAIMABLE_B;
-}
-
#ifdef CONFIG_MEMCG_KMEM
static inline void memcg_free_slab_cgroups(struct slab *slab)
{
@@ -1888,79 +1882,6 @@ static inline void memcg_free_slab_cgroups(struct slab *slab)
slab->memcg_data = 0;
}

-static inline size_t obj_full_size(struct kmem_cache *s)
-{
- /*
- * For each accounted object there is an extra space which is used
- * to store obj_cgroup membership. Charge it too.
- */
- return s->size + sizeof(struct obj_cgroup *);
-}
-
-static bool __memcg_slab_post_alloc_hook(struct kmem_cache *s,
- struct list_lru *lru,
- gfp_t flags, size_t size,
- void **p)
-{
- struct obj_cgroup *objcg;
- struct slab *slab;
- unsigned long off;
- size_t i;
-
- /*
- * The obtained objcg pointer is safe to use within the current scope,
- * defined by current task or set_active_memcg() pair.
- * obj_cgroup_get() is used to get a permanent reference.
- */
- objcg = current_obj_cgroup();
- if (!objcg)
- return true;
-
- /*
- * slab_alloc_node() avoids the NULL check, so we might be called with a
- * single NULL object. kmem_cache_alloc_bulk() aborts if it can't fill
- * the whole requested size.
- * return success as there's nothing to free back
- */
- if (unlikely(*p == NULL))
- return true;
-
- flags &= gfp_allowed_mask;
-
- if (lru) {
- int ret;
- struct mem_cgroup *memcg;
-
- memcg = get_mem_cgroup_from_objcg(objcg);
- ret = memcg_list_lru_alloc(memcg, lru, flags);
- css_put(&memcg->css);
-
- if (ret)
- return false;
- }
-
- if (obj_cgroup_charge(objcg, flags, size * obj_full_size(s)))
- return false;
-
- for (i = 0; i < size; i++) {
- slab = virt_to_slab(p[i]);
-
- if (!slab_objcgs(slab) &&
- memcg_alloc_slab_cgroups(slab, s, flags, false)) {
- obj_cgroup_uncharge(objcg, obj_full_size(s));
- continue;
- }
-
- off = obj_to_index(s, slab, p[i]);
- obj_cgroup_get(objcg);
- slab_objcgs(slab)[off] = objcg;
- mod_objcg_state(objcg, slab_pgdat(slab),
- cache_vmstat_idx(s), obj_full_size(s));
- }
-
- return true;
-}
-
static void memcg_alloc_abort_single(struct kmem_cache *s, void *object);

static __fastpath_inline
@@ -1986,27 +1907,6 @@ bool memcg_slab_post_alloc_hook(struct kmem_cache *s, struct list_lru *lru,
return false;
}

-static void __memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab,
- void **p, int objects,
- struct obj_cgroup **objcgs)
-{
- for (int i = 0; i < objects; i++) {
- struct obj_cgroup *objcg;
- unsigned int off;
-
- off = obj_to_index(s, slab, p[i]);
- objcg = objcgs[off];
- if (!objcg)
- continue;
-
- objcgs[off] = NULL;
- obj_cgroup_uncharge(objcg, obj_full_size(s));
- mod_objcg_state(objcg, slab_pgdat(slab), cache_vmstat_idx(s),
- -obj_full_size(s));
- obj_cgroup_put(objcg);
- }
-}
-
static __fastpath_inline
void memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab, void **p,
int objects)

--
2.44.0