Commit f7a449f7 authored by Roman Gushchin's avatar Roman Gushchin Committed by Andrew Morton
Browse files

mm: memcontrol: rename memcg_kmem_enabled() 

Currently there are two kmem-related helper functions with a confusing
semantics: memcg_kmem_enabled() and mem_cgroup_kmem_disabled().

The problem is that an obvious expectation
memcg_kmem_enabled() == !mem_cgroup_kmem_disabled(),
can be false.

mem_cgroup_kmem_disabled() is similar to mem_cgroup_disabled(): it returns
true only if CONFIG_MEMCG_KMEM is not set or the kmem accounting is
disabled using a boot time kernel option "cgroup.memory=nokmem".  It never
changes the value dynamically.

memcg_kmem_enabled() is different: it always returns false until the first
non-root memory cgroup will get online (assuming the kernel memory
accounting is enabled).  It's goal is to improve the performance on
systems without the cgroupfs mounted/memory controller enabled or on the
systems with only the root memory cgroup.

To make things more obvious and avoid potential bugs, let's rename
memcg_kmem_enabled() to memcg_kmem_online().

Link: https://lkml.kernel.org/r/20230213192922.1146370-1-roman.gushchin@linux.dev


Signed-off-by: default avatarRoman Gushchin <roman.gushchin@linux.dev>
Acked-by: default avatarMuchun Song <songmuchun@bytedance.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Dennis Zhou <dennis@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent b4fb12e6

include/linux/memcontrol.h

+7 −7
Original line number Diff line number Diff line
@@ -1776,24 +1776,24 @@ struct obj_cgroup *get_obj_cgroup_from_page(struct page *page); 
int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size);

void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size);



extern struct static_key_false memcg_kmem_enabled_key;

extern struct static_key_false memcg_kmem_online_key;



static inline bool memcg_kmem_enabled(void)

static inline bool memcg_kmem_online(void)

{

	return static_branch_likely(&memcg_kmem_enabled_key);

	return static_branch_likely(&memcg_kmem_online_key);

}



static inline int memcg_kmem_charge_page(struct page *page, gfp_t gfp,

					 int order)

{

	if (memcg_kmem_enabled())

	if (memcg_kmem_online())

		return __memcg_kmem_charge_page(page, gfp, order);

	return 0;

}



static inline void memcg_kmem_uncharge_page(struct page *page, int order)

{

	if (memcg_kmem_enabled())

	if (memcg_kmem_online())

		__memcg_kmem_uncharge_page(page, order);

}
@@ -1814,7 +1814,7 @@ static inline void count_objcg_event(struct obj_cgroup *objcg, 
{

	struct mem_cgroup *memcg;



	if (!memcg_kmem_enabled())

	if (!memcg_kmem_online())

		return;



	rcu_read_lock();
@@ -1854,7 +1854,7 @@ static inline struct obj_cgroup *get_obj_cgroup_from_page(struct page *page) 
	return NULL;

}



static inline bool memcg_kmem_enabled(void)

static inline bool memcg_kmem_online(void)

{

	return false;

}

mm/memcontrol.c

+4 −4
Original line number Diff line number Diff line
@@ -345,8 +345,8 @@ static void memcg_reparent_objcgs(struct mem_cgroup *memcg, 
 * conditional to this static branch, we'll have to allow modules that does

 * kmem_cache_alloc and the such to see this symbol as well

 */

DEFINE_STATIC_KEY_FALSE(memcg_kmem_enabled_key);

EXPORT_SYMBOL(memcg_kmem_enabled_key);

DEFINE_STATIC_KEY_FALSE(memcg_kmem_online_key);

EXPORT_SYMBOL(memcg_kmem_online_key);

#endif



/**
@@ -3034,7 +3034,7 @@ struct obj_cgroup *get_obj_cgroup_from_page(struct page *page) 
{

	struct obj_cgroup *objcg;



	if (!memcg_kmem_enabled())

	if (!memcg_kmem_online())

		return NULL;



	if (PageMemcgKmem(page)) {
@@ -3746,7 +3746,7 @@ static int memcg_online_kmem(struct mem_cgroup *memcg) 
	objcg->memcg = memcg;

	rcu_assign_pointer(memcg->objcg, objcg);



	static_branch_enable(&memcg_kmem_enabled_key);

	static_branch_enable(&memcg_kmem_online_key);



	memcg->kmemcg_id = memcg->id.id;

mm/page_alloc.c

+4 −4
Original line number Diff line number Diff line
@@ -1410,7 +1410,7 @@ static __always_inline bool free_pages_prepare(struct page *page, 
		 * Do not let hwpoison pages hit pcplists/buddy

		 * Untie memcg state and reset page's owner

		 */

		if (memcg_kmem_enabled() && PageMemcgKmem(page))

		if (memcg_kmem_online() && PageMemcgKmem(page))

			__memcg_kmem_uncharge_page(page, order);

		reset_page_owner(page, order);

		page_table_check_free(page, order);
@@ -1441,7 +1441,7 @@ static __always_inline bool free_pages_prepare(struct page *page, 
	}

	if (PageMappingFlags(page))

		page->mapping = NULL;

	if (memcg_kmem_enabled() && PageMemcgKmem(page))

	if (memcg_kmem_online() && PageMemcgKmem(page))

		__memcg_kmem_uncharge_page(page, order);

	if (check_free && free_page_is_bad(page))

		bad++;
@@ -5432,7 +5432,7 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid, 
		goto out;



	/* Bulk allocator does not support memcg accounting. */

	if (memcg_kmem_enabled() && (gfp & __GFP_ACCOUNT))

	if (memcg_kmem_online() && (gfp & __GFP_ACCOUNT))

		goto failed;



	/* Use the single page allocator for one page. */
@@ -5604,7 +5604,7 @@ struct page *__alloc_pages(gfp_t gfp, unsigned int order, int preferred_nid, 
	page = __alloc_pages_slowpath(alloc_gfp, order, &ac);



out:

	if (memcg_kmem_enabled() && (gfp & __GFP_ACCOUNT) && page &&

	if (memcg_kmem_online() && (gfp & __GFP_ACCOUNT) && page &&

	    unlikely(__memcg_kmem_charge_page(page, gfp, order) != 0)) {

		__free_pages(page, order);

		page = NULL;

mm/percpu.c

+1 −1
Original line number Diff line number Diff line
@@ -1625,7 +1625,7 @@ static bool pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp, 
{

	struct obj_cgroup *objcg;



	if (!memcg_kmem_enabled() || !(gfp & __GFP_ACCOUNT))

	if (!memcg_kmem_online() || !(gfp & __GFP_ACCOUNT))

		return true;



	objcg = get_obj_cgroup_from_current();

mm/slab.h

+5 −5
Original line number Diff line number Diff line
@@ -494,7 +494,7 @@ static inline bool memcg_slab_pre_alloc_hook(struct kmem_cache *s, 
{

	struct obj_cgroup *objcg;



	if (!memcg_kmem_enabled())

	if (!memcg_kmem_online())

		return true;



	if (!(flags & __GFP_ACCOUNT) && !(s->flags & SLAB_ACCOUNT))
@@ -535,7 +535,7 @@ static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s, 
	unsigned long off;

	size_t i;



	if (!memcg_kmem_enabled() || !objcg)

	if (!memcg_kmem_online() || !objcg)

		return;



	for (i = 0; i < size; i++) {
@@ -567,7 +567,7 @@ static inline void memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab, 
	struct obj_cgroup **objcgs;

	int i;



	if (!memcg_kmem_enabled())

	if (!memcg_kmem_online())

		return;



	objcgs = slab_objcgs(slab);
@@ -649,7 +649,7 @@ static inline struct kmem_cache *virt_to_cache(const void *obj) 
static __always_inline void account_slab(struct slab *slab, int order,

					 struct kmem_cache *s, gfp_t gfp)

{

	if (memcg_kmem_enabled() && (s->flags & SLAB_ACCOUNT))

	if (memcg_kmem_online() && (s->flags & SLAB_ACCOUNT))

		memcg_alloc_slab_cgroups(slab, s, gfp, true);



	mod_node_page_state(slab_pgdat(slab), cache_vmstat_idx(s),
@@ -659,7 +659,7 @@ 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_enabled())

	if (memcg_kmem_online())

		memcg_free_slab_cgroups(slab);



	mod_node_page_state(slab_pgdat(slab), cache_vmstat_idx(s),