mm: remove CONFIG_MEMCG_KMEM

CONFIG_MEMCG_KMEM used to be a user-visible option for whether slab
tracking is enabled.  It has been default-enabled and equivalent to
CONFIG_MEMCG for almost a decade.  We've only grown more kernel memory
accounting sites since, and there is no imaginable cgroup usecase going
forward that wants to track user pages but not the multitude of
user-drivable kernel allocations.

Link: https://lkml.kernel.org/r/20240701153148.452230-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

6 files changed, 17 insertions, 30 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 5e694a308081..b8637555c9c2 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -275,7 +275,7 @@ struct bpf_map {
 	u32 btf_value_type_id;
 	u32 btf_vmlinux_value_type_id;
 	struct btf *btf;
-#ifdef CONFIG_MEMCG_KMEM
+#ifdef CONFIG_MEMCG
 	struct obj_cgroup *objcg;
 #endif
 	char name[BPF_OBJ_NAME_LEN];
@@ -2252,7 +2252,7 @@ struct bpf_prog *bpf_prog_get_curr_or_next(u32 *id);
 
 int bpf_map_alloc_pages(const struct bpf_map *map, gfp_t gfp, int nid,
 			unsigned long nr_pages, struct page **page_array);
-#ifdef CONFIG_MEMCG_KMEM
+#ifdef CONFIG_MEMCG
 void *bpf_map_kmalloc_node(const struct bpf_map *map, size_t size, gfp_t flags,
 			   int node);
 void *bpf_map_kzalloc(const struct bpf_map *map, size_t size, gfp_t flags);
diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h
index 792b67ceb631..5099a8ccd5f4 100644
--- a/include/linux/list_lru.h
+++ b/include/linux/list_lru.h
@@ -50,7 +50,7 @@ struct list_lru_node {
 
 struct list_lru {
 	struct list_lru_node	*node;
-#ifdef CONFIG_MEMCG_KMEM
+#ifdef CONFIG_MEMCG
 	struct list_head	list;
 	int			shrinker_id;
 	bool			memcg_aware;
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 60418934827c..7e2eb091049a 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -195,7 +195,7 @@ struct mem_cgroup {
 	/* Range enforcement for interrupt charges */
 	struct work_struct high_work;
 
-#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
+#ifdef CONFIG_ZSWAP
 	unsigned long zswap_max;
 
 	/*
@@ -236,7 +236,6 @@ struct mem_cgroup {
 	 */
 	unsigned long		socket_pressure;
 
-#ifdef CONFIG_MEMCG_KMEM
 	int kmemcg_id;
 	/*
 	 * memcg->objcg is wiped out as a part of the objcg repaprenting
@@ -247,7 +246,6 @@ struct mem_cgroup {
 	struct obj_cgroup	*orig_objcg;
 	/* list of inherited objcgs, protected by objcg_lock */
 	struct list_head objcg_list;
-#endif
 
 	struct memcg_vmstats_percpu __percpu *vmstats_percpu;
 
@@ -532,7 +530,6 @@ retry:
 	return memcg;
 }
 
-#ifdef CONFIG_MEMCG_KMEM
 /*
  * folio_memcg_kmem - Check if the folio has the memcg_kmem flag set.
  * @folio: Pointer to the folio.
@@ -548,15 +545,6 @@ static inline bool folio_memcg_kmem(struct folio *folio)
 	return folio->memcg_data & MEMCG_DATA_KMEM;
 }
 
-
-#else
-static inline bool folio_memcg_kmem(struct folio *folio)
-{
-	return false;
-}
-
-#endif
-
 static inline bool PageMemcgKmem(struct page *page)
 {
 	return folio_memcg_kmem(page_folio(page));
@@ -1488,7 +1476,7 @@ static inline void split_page_memcg(struct page *head, int old_order, int new_or
  * if MEMCG_DATA_OBJEXTS is set.
  */
 struct slabobj_ext {
-#ifdef CONFIG_MEMCG_KMEM
+#ifdef CONFIG_MEMCG
 	struct obj_cgroup *objcg;
 #endif
 #ifdef CONFIG_MEM_ALLOC_PROFILING
@@ -1663,7 +1651,7 @@ static inline void set_shrinker_bit(struct mem_cgroup *memcg,
 }
 #endif
 
-#ifdef CONFIG_MEMCG_KMEM
+#ifdef CONFIG_MEMCG
 bool mem_cgroup_kmem_disabled(void);
 int __memcg_kmem_charge_page(struct page *page, gfp_t gfp, int order);
 void __memcg_kmem_uncharge_page(struct page *page, int order);
@@ -1806,9 +1794,9 @@ static inline void count_objcg_event(struct obj_cgroup *objcg,
 {
 }
 
-#endif /* CONFIG_MEMCG_KMEM */
+#endif /* CONFIG_MEMCG */
 
-#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
+#if defined(CONFIG_MEMCG) && defined(CONFIG_ZSWAP)
 bool obj_cgroup_may_zswap(struct obj_cgroup *objcg);
 void obj_cgroup_charge_zswap(struct obj_cgroup *objcg, size_t size);
 void obj_cgroup_uncharge_zswap(struct obj_cgroup *objcg, size_t size);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index a7770c566c4d..82da65131a6b 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1457,9 +1457,8 @@ struct task_struct {
 
 	/* Used by memcontrol for targeted memcg charge: */
 	struct mem_cgroup		*active_memcg;
-#endif
 
-#ifdef CONFIG_MEMCG_KMEM
+	/* Cache for current->cgroups->memcg->objcg lookups: */
 	struct obj_cgroup		*objcg;
 #endif
 
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 7247e217e21b..a332dd2fa6cd 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -41,7 +41,7 @@ enum _slab_flag_bits {
 #ifdef CONFIG_FAILSLAB
 	_SLAB_FAILSLAB,
 #endif
-#ifdef CONFIG_MEMCG_KMEM
+#ifdef CONFIG_MEMCG
 	_SLAB_ACCOUNT,
 #endif
 #ifdef CONFIG_KASAN_GENERIC
@@ -171,7 +171,7 @@ enum _slab_flag_bits {
 # define SLAB_FAILSLAB		__SLAB_FLAG_UNUSED
 #endif
 /* Account to memcg */
-#ifdef CONFIG_MEMCG_KMEM
+#ifdef CONFIG_MEMCG
 # define SLAB_ACCOUNT		__SLAB_FLAG_BIT(_SLAB_ACCOUNT)
 #else
 # define SLAB_ACCOUNT		__SLAB_FLAG_UNUSED
@@ -407,7 +407,7 @@ enum kmalloc_cache_type {
 #ifndef CONFIG_ZONE_DMA
 	KMALLOC_DMA = KMALLOC_NORMAL,
 #endif
-#ifndef CONFIG_MEMCG_KMEM
+#ifndef CONFIG_MEMCG
 	KMALLOC_CGROUP = KMALLOC_NORMAL,
 #endif
 	KMALLOC_RANDOM_START = KMALLOC_NORMAL,
@@ -420,7 +420,7 @@ enum kmalloc_cache_type {
 #ifdef CONFIG_ZONE_DMA
 	KMALLOC_DMA,
 #endif
-#ifdef CONFIG_MEMCG_KMEM
+#ifdef CONFIG_MEMCG
 	KMALLOC_CGROUP,
 #endif
 	NR_KMALLOC_TYPES
@@ -435,7 +435,7 @@ kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1];
 #define KMALLOC_NOT_NORMAL_BITS					\
 	(__GFP_RECLAIMABLE |					\
 	(IS_ENABLED(CONFIG_ZONE_DMA)   ? __GFP_DMA : 0) |	\
-	(IS_ENABLED(CONFIG_MEMCG_KMEM) ? __GFP_ACCOUNT : 0))
+	(IS_ENABLED(CONFIG_MEMCG) ? __GFP_ACCOUNT : 0))
 
 extern unsigned long random_kmalloc_seed;
 
@@ -463,7 +463,7 @@ static __always_inline enum kmalloc_cache_type kmalloc_type(gfp_t flags, unsigne
 	 */
 	if (IS_ENABLED(CONFIG_ZONE_DMA) && (flags & __GFP_DMA))
 		return KMALLOC_DMA;
-	if (!IS_ENABLED(CONFIG_MEMCG_KMEM) || (flags & __GFP_RECLAIMABLE))
+	if (!IS_ENABLED(CONFIG_MEMCG) || (flags & __GFP_RECLAIMABLE))
 		return KMALLOC_RECLAIM;
 	else
 		return KMALLOC_CGROUP;
diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h
index 8a829e0f6e55..b37eb0a7060f 100644
--- a/include/trace/events/kmem.h
+++ b/include/trace/events/kmem.h
@@ -36,7 +36,7 @@ TRACE_EVENT(kmem_cache_alloc,
 		__entry->bytes_alloc	= s->size;
 		__entry->gfp_flags	= (__force unsigned long)gfp_flags;
 		__entry->node		= node;
-		__entry->accounted	= IS_ENABLED(CONFIG_MEMCG_KMEM) ?
+		__entry->accounted	= IS_ENABLED(CONFIG_MEMCG) ?
 					  ((gfp_flags & __GFP_ACCOUNT) ||
 					  (s->flags & SLAB_ACCOUNT)) : false;
 	),
@@ -87,7 +87,7 @@ TRACE_EVENT(kmalloc,
 		__entry->bytes_alloc,
 		show_gfp_flags(__entry->gfp_flags),
 		__entry->node,
-		(IS_ENABLED(CONFIG_MEMCG_KMEM) &&
+		(IS_ENABLED(CONFIG_MEMCG) &&
 		 (__entry->gfp_flags & (__force unsigned long)__GFP_ACCOUNT)) ? "true" : "false")
 );