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memcg, slab: separate memcg vs root cache creation paths
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Memcg-awareness turned kmem_cache_create() into a dirty interweaving of
memcg-only and except-for-memcg calls.  To clean this up, let's move the
code responsible for memcg cache creation to a separate function.

Signed-off-by: Vladimir Davydov <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: Glauber Costa <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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@torvalds
Vladimir Davydov authored and torvalds committed Apr 7, 2014
1 parent 5722d09 commit 794b124
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Showing 4 changed files with 111 additions and 95 deletions.
6 changes: 0 additions & 6 deletions include/linux/memcontrol.h
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Original file line number Diff line number Diff line change
Expand Up @@ -638,12 +638,6 @@ static inline int memcg_cache_id(struct mem_cgroup *memcg)
return -1;
}

static inline char *memcg_create_cache_name(struct mem_cgroup *memcg,
struct kmem_cache *root_cache)
{
return NULL;
}

static inline int memcg_alloc_cache_params(struct mem_cgroup *memcg,
struct kmem_cache *s, struct kmem_cache *root_cache)
{
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6 changes: 3 additions & 3 deletions include/linux/slab.h
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Original file line number Diff line number Diff line change
Expand Up @@ -115,9 +115,9 @@ int slab_is_available(void);
struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
unsigned long,
void (*)(void *));
struct kmem_cache *
kmem_cache_create_memcg(struct mem_cgroup *, const char *, size_t, size_t,
unsigned long, void (*)(void *), struct kmem_cache *);
#ifdef CONFIG_MEMCG_KMEM
void kmem_cache_create_memcg(struct mem_cgroup *, struct kmem_cache *);
#endif
void kmem_cache_destroy(struct kmem_cache *);
int kmem_cache_shrink(struct kmem_cache *);
void kmem_cache_free(struct kmem_cache *, void *);
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7 changes: 1 addition & 6 deletions mm/memcontrol.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3395,13 +3395,8 @@ static void memcg_create_cache_work_func(struct work_struct *w)
struct create_work *cw = container_of(w, struct create_work, work);
struct mem_cgroup *memcg = cw->memcg;
struct kmem_cache *cachep = cw->cachep;
struct kmem_cache *new;

new = kmem_cache_create_memcg(memcg, cachep->name,
cachep->object_size, cachep->align,
cachep->flags & ~SLAB_PANIC, cachep->ctor, cachep);
if (new)
new->allocflags |= __GFP_KMEMCG;
kmem_cache_create_memcg(memcg, cachep);
css_put(&memcg->css);
kfree(cw);
}
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187 changes: 107 additions & 80 deletions mm/slab_common.c
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Original file line number Diff line number Diff line change
Expand Up @@ -29,8 +29,7 @@ DEFINE_MUTEX(slab_mutex);
struct kmem_cache *kmem_cache;

#ifdef CONFIG_DEBUG_VM
static int kmem_cache_sanity_check(struct mem_cgroup *memcg, const char *name,
size_t size)
static int kmem_cache_sanity_check(const char *name, size_t size)
{
struct kmem_cache *s = NULL;

Expand All @@ -57,13 +56,7 @@ static int kmem_cache_sanity_check(struct mem_cgroup *memcg, const char *name,
}

#if !defined(CONFIG_SLUB) || !defined(CONFIG_SLUB_DEBUG_ON)
/*
* For simplicity, we won't check this in the list of memcg
* caches. We have control over memcg naming, and if there
* aren't duplicates in the global list, there won't be any
* duplicates in the memcg lists as well.
*/
if (!memcg && !strcmp(s->name, name)) {
if (!strcmp(s->name, name)) {
pr_err("%s (%s): Cache name already exists.\n",
__func__, name);
dump_stack();
Expand All @@ -77,8 +70,7 @@ static int kmem_cache_sanity_check(struct mem_cgroup *memcg, const char *name,
return 0;
}
#else
static inline int kmem_cache_sanity_check(struct mem_cgroup *memcg,
const char *name, size_t size)
static inline int kmem_cache_sanity_check(const char *name, size_t size)
{
return 0;
}
Expand Down Expand Up @@ -139,6 +131,46 @@ unsigned long calculate_alignment(unsigned long flags,
return ALIGN(align, sizeof(void *));
}

static struct kmem_cache *
do_kmem_cache_create(char *name, size_t object_size, size_t size, size_t align,
unsigned long flags, void (*ctor)(void *),
struct mem_cgroup *memcg, struct kmem_cache *root_cache)
{
struct kmem_cache *s;
int err;

err = -ENOMEM;
s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
if (!s)
goto out;

s->name = name;
s->object_size = object_size;
s->size = size;
s->align = align;
s->ctor = ctor;

err = memcg_alloc_cache_params(memcg, s, root_cache);
if (err)
goto out_free_cache;

err = __kmem_cache_create(s, flags);
if (err)
goto out_free_cache;

s->refcount = 1;
list_add(&s->list, &slab_caches);
memcg_register_cache(s);
out:
if (err)
return ERR_PTR(err);
return s;

out_free_cache:
memcg_free_cache_params(s);
kfree(s);
goto out;
}

/*
* kmem_cache_create - Create a cache.
Expand All @@ -164,34 +196,21 @@ unsigned long calculate_alignment(unsigned long flags,
* cacheline. This can be beneficial if you're counting cycles as closely
* as davem.
*/

struct kmem_cache *
kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
size_t align, unsigned long flags, void (*ctor)(void *),
struct kmem_cache *parent_cache)
kmem_cache_create(const char *name, size_t size, size_t align,
unsigned long flags, void (*ctor)(void *))
{
struct kmem_cache *s = NULL;
struct kmem_cache *s;
char *cache_name;
int err;

get_online_cpus();
mutex_lock(&slab_mutex);

err = kmem_cache_sanity_check(memcg, name, size);
err = kmem_cache_sanity_check(name, size);
if (err)
goto out_unlock;

if (memcg) {
/*
* Since per-memcg caches are created asynchronously on first
* allocation (see memcg_kmem_get_cache()), several threads can
* try to create the same cache, but only one of them may
* succeed. Therefore if we get here and see the cache has
* already been created, we silently return NULL.
*/
if (cache_from_memcg_idx(parent_cache, memcg_cache_id(memcg)))
goto out_unlock;
}

/*
* Some allocators will constraint the set of valid flags to a subset
* of all flags. We expect them to define CACHE_CREATE_MASK in this
Expand All @@ -200,55 +219,29 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
*/
flags &= CACHE_CREATE_MASK;

if (!memcg) {
s = __kmem_cache_alias(name, size, align, flags, ctor);
if (s)
goto out_unlock;
}

err = -ENOMEM;
s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
if (!s)
s = __kmem_cache_alias(name, size, align, flags, ctor);
if (s)
goto out_unlock;

s->object_size = s->size = size;
s->align = calculate_alignment(flags, align, size);
s->ctor = ctor;

if (memcg)
s->name = memcg_create_cache_name(memcg, parent_cache);
else
s->name = kstrdup(name, GFP_KERNEL);
if (!s->name)
goto out_free_cache;

err = memcg_alloc_cache_params(memcg, s, parent_cache);
if (err)
goto out_free_cache;

err = __kmem_cache_create(s, flags);
if (err)
goto out_free_cache;
cache_name = kstrdup(name, GFP_KERNEL);
if (!cache_name) {
err = -ENOMEM;
goto out_unlock;
}

s->refcount = 1;
list_add(&s->list, &slab_caches);
memcg_register_cache(s);
s = do_kmem_cache_create(cache_name, size, size,
calculate_alignment(flags, align, size),
flags, ctor, NULL, NULL);
if (IS_ERR(s)) {
err = PTR_ERR(s);
kfree(cache_name);
}

out_unlock:
mutex_unlock(&slab_mutex);
put_online_cpus();

if (err) {
/*
* There is no point in flooding logs with warnings or
* especially crashing the system if we fail to create a cache
* for a memcg. In this case we will be accounting the memcg
* allocation to the root cgroup until we succeed to create its
* own cache, but it isn't that critical.
*/
if (!memcg)
return NULL;

if (flags & SLAB_PANIC)
panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
name, err);
Expand All @@ -260,21 +253,55 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
return NULL;
}
return s;

out_free_cache:
memcg_free_cache_params(s);
kfree(s->name);
kmem_cache_free(kmem_cache, s);
goto out_unlock;
}
EXPORT_SYMBOL(kmem_cache_create);

struct kmem_cache *
kmem_cache_create(const char *name, size_t size, size_t align,
unsigned long flags, void (*ctor)(void *))
#ifdef CONFIG_MEMCG_KMEM
/*
* kmem_cache_create_memcg - Create a cache for a memory cgroup.
* @memcg: The memory cgroup the new cache is for.
* @root_cache: The parent of the new cache.
*
* This function attempts to create a kmem cache that will serve allocation
* requests going from @memcg to @root_cache. The new cache inherits properties
* from its parent.
*/
void kmem_cache_create_memcg(struct mem_cgroup *memcg, struct kmem_cache *root_cache)
{
return kmem_cache_create_memcg(NULL, name, size, align, flags, ctor, NULL);
struct kmem_cache *s;
char *cache_name;

get_online_cpus();
mutex_lock(&slab_mutex);

/*
* Since per-memcg caches are created asynchronously on first
* allocation (see memcg_kmem_get_cache()), several threads can try to
* create the same cache, but only one of them may succeed.
*/
if (cache_from_memcg_idx(root_cache, memcg_cache_id(memcg)))
goto out_unlock;

cache_name = memcg_create_cache_name(memcg, root_cache);
if (!cache_name)
goto out_unlock;

s = do_kmem_cache_create(cache_name, root_cache->object_size,
root_cache->size, root_cache->align,
root_cache->flags, root_cache->ctor,
memcg, root_cache);
if (IS_ERR(s)) {
kfree(cache_name);
goto out_unlock;
}

s->allocflags |= __GFP_KMEMCG;

out_unlock:
mutex_unlock(&slab_mutex);
put_online_cpus();
}
EXPORT_SYMBOL(kmem_cache_create);
#endif /* CONFIG_MEMCG_KMEM */

void kmem_cache_destroy(struct kmem_cache *s)
{
Expand Down

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