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authorRoman Gushchin <guro@fb.com>2020-08-06 23:21:27 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-08-07 11:33:25 -0700
commit10befea91b61c4e2c2d1df06a2e978d182fcf792 (patch)
treecc5c9a0e4d351194ccde996f5455248f45b5d56c /mm/slub.c
parent15999eef7f25e2ea6a1c33f026166f472c5714e9 (diff)
downloadlwn-10befea91b61c4e2c2d1df06a2e978d182fcf792.tar.gz
lwn-10befea91b61c4e2c2d1df06a2e978d182fcf792.zip
mm: memcg/slab: use a single set of kmem_caches for all allocations
Instead of having two sets of kmem_caches: one for system-wide and non-accounted allocations and the second one shared by all accounted allocations, we can use just one. The idea is simple: space for obj_cgroup metadata can be allocated on demand and filled only for accounted allocations. It allows to remove a bunch of code which is required to handle kmem_cache clones for accounted allocations. There is no more need to create them, accumulate statistics, propagate attributes, etc. It's a quite significant simplification. Also, because the total number of slab_caches is reduced almost twice (not all kmem_caches have a memcg clone), some additional memory savings are expected. On my devvm it additionally saves about 3.5% of slab memory. [guro@fb.com: fix build on MIPS] Link: http://lkml.kernel.org/r/20200717214810.3733082-1-guro@fb.com Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Naresh Kamboju <naresh.kamboju@linaro.org> Link: http://lkml.kernel.org/r/20200623174037.3951353-18-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slub.c')
-rw-r--r--mm/slub.c163
1 files changed, 4 insertions, 159 deletions
diff --git a/mm/slub.c b/mm/slub.c
index 9cd724fe37d8..eba8f57d5734 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -218,14 +218,10 @@ enum track_item { TRACK_ALLOC, TRACK_FREE };
#ifdef CONFIG_SYSFS
static int sysfs_slab_add(struct kmem_cache *);
static int sysfs_slab_alias(struct kmem_cache *, const char *);
-static void memcg_propagate_slab_attrs(struct kmem_cache *s);
-static void sysfs_slab_remove(struct kmem_cache *s);
#else
static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; }
static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p)
{ return 0; }
-static inline void memcg_propagate_slab_attrs(struct kmem_cache *s) { }
-static inline void sysfs_slab_remove(struct kmem_cache *s) { }
#endif
static inline void stat(const struct kmem_cache *s, enum stat_item si)
@@ -1624,10 +1620,8 @@ static inline struct page *alloc_slab_page(struct kmem_cache *s,
else
page = __alloc_pages_node(node, flags, order);
- if (page && charge_slab_page(page, flags, order, s)) {
- __free_pages(page, order);
- page = NULL;
- }
+ if (page)
+ charge_slab_page(page, flags, order, s);
return page;
}
@@ -3920,7 +3914,6 @@ int __kmem_cache_shutdown(struct kmem_cache *s)
if (n->nr_partial || slabs_node(s, node))
return 1;
}
- sysfs_slab_remove(s);
return 0;
}
@@ -4358,7 +4351,6 @@ static struct kmem_cache * __init bootstrap(struct kmem_cache *static_cache)
p->slab_cache = s;
#endif
}
- slab_init_memcg_params(s);
list_add(&s->list, &slab_caches);
return s;
}
@@ -4414,7 +4406,7 @@ struct kmem_cache *
__kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
slab_flags_t flags, void (*ctor)(void *))
{
- struct kmem_cache *s, *c;
+ struct kmem_cache *s;
s = find_mergeable(size, align, flags, name, ctor);
if (s) {
@@ -4427,12 +4419,6 @@ __kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
s->object_size = max(s->object_size, size);
s->inuse = max(s->inuse, ALIGN(size, sizeof(void *)));
- c = memcg_cache(s);
- if (c) {
- c->object_size = s->object_size;
- c->inuse = max(c->inuse, ALIGN(size, sizeof(void *)));
- }
-
if (sysfs_slab_alias(s, name)) {
s->refcount--;
s = NULL;
@@ -4454,7 +4440,6 @@ int __kmem_cache_create(struct kmem_cache *s, slab_flags_t flags)
if (slab_state <= UP)
return 0;
- memcg_propagate_slab_attrs(s);
err = sysfs_slab_add(s);
if (err)
__kmem_cache_release(s);
@@ -5312,7 +5297,7 @@ static ssize_t shrink_store(struct kmem_cache *s,
const char *buf, size_t length)
{
if (buf[0] == '1')
- kmem_cache_shrink_all(s);
+ kmem_cache_shrink(s);
else
return -EINVAL;
return length;
@@ -5536,99 +5521,9 @@ static ssize_t slab_attr_store(struct kobject *kobj,
return -EIO;
err = attribute->store(s, buf, len);
-#ifdef CONFIG_MEMCG
- if (slab_state >= FULL && err >= 0 && is_root_cache(s)) {
- struct kmem_cache *c;
-
- mutex_lock(&slab_mutex);
- if (s->max_attr_size < len)
- s->max_attr_size = len;
-
- /*
- * This is a best effort propagation, so this function's return
- * value will be determined by the parent cache only. This is
- * basically because not all attributes will have a well
- * defined semantics for rollbacks - most of the actions will
- * have permanent effects.
- *
- * Returning the error value of any of the children that fail
- * is not 100 % defined, in the sense that users seeing the
- * error code won't be able to know anything about the state of
- * the cache.
- *
- * Only returning the error code for the parent cache at least
- * has well defined semantics. The cache being written to
- * directly either failed or succeeded, in which case we loop
- * through the descendants with best-effort propagation.
- */
- c = memcg_cache(s);
- if (c)
- attribute->store(c, buf, len);
- mutex_unlock(&slab_mutex);
- }
-#endif
return err;
}
-static void memcg_propagate_slab_attrs(struct kmem_cache *s)
-{
-#ifdef CONFIG_MEMCG
- int i;
- char *buffer = NULL;
- struct kmem_cache *root_cache;
-
- if (is_root_cache(s))
- return;
-
- root_cache = s->memcg_params.root_cache;
-
- /*
- * This mean this cache had no attribute written. Therefore, no point
- * in copying default values around
- */
- if (!root_cache->max_attr_size)
- return;
-
- for (i = 0; i < ARRAY_SIZE(slab_attrs); i++) {
- char mbuf[64];
- char *buf;
- struct slab_attribute *attr = to_slab_attr(slab_attrs[i]);
- ssize_t len;
-
- if (!attr || !attr->store || !attr->show)
- continue;
-
- /*
- * It is really bad that we have to allocate here, so we will
- * do it only as a fallback. If we actually allocate, though,
- * we can just use the allocated buffer until the end.
- *
- * Most of the slub attributes will tend to be very small in
- * size, but sysfs allows buffers up to a page, so they can
- * theoretically happen.
- */
- if (buffer)
- buf = buffer;
- else if (root_cache->max_attr_size < ARRAY_SIZE(mbuf) &&
- !IS_ENABLED(CONFIG_SLUB_STATS))
- buf = mbuf;
- else {
- buffer = (char *) get_zeroed_page(GFP_KERNEL);
- if (WARN_ON(!buffer))
- continue;
- buf = buffer;
- }
-
- len = attr->show(root_cache, buf);
- if (len > 0)
- attr->store(s, buf, len);
- }
-
- if (buffer)
- free_page((unsigned long)buffer);
-#endif /* CONFIG_MEMCG */
-}
-
static void kmem_cache_release(struct kobject *k)
{
slab_kmem_cache_release(to_slab(k));
@@ -5648,10 +5543,6 @@ static struct kset *slab_kset;
static inline struct kset *cache_kset(struct kmem_cache *s)
{
-#ifdef CONFIG_MEMCG
- if (!is_root_cache(s))
- return s->memcg_params.root_cache->memcg_kset;
-#endif
return slab_kset;
}
@@ -5694,27 +5585,6 @@ static char *create_unique_id(struct kmem_cache *s)
return name;
}
-static void sysfs_slab_remove_workfn(struct work_struct *work)
-{
- struct kmem_cache *s =
- container_of(work, struct kmem_cache, kobj_remove_work);
-
- if (!s->kobj.state_in_sysfs)
- /*
- * For a memcg cache, this may be called during
- * deactivation and again on shutdown. Remove only once.
- * A cache is never shut down before deactivation is
- * complete, so no need to worry about synchronization.
- */
- goto out;
-
-#ifdef CONFIG_MEMCG
- kset_unregister(s->memcg_kset);
-#endif
-out:
- kobject_put(&s->kobj);
-}
-
static int sysfs_slab_add(struct kmem_cache *s)
{
int err;
@@ -5722,8 +5592,6 @@ static int sysfs_slab_add(struct kmem_cache *s)
struct kset *kset = cache_kset(s);
int unmergeable = slab_unmergeable(s);
- INIT_WORK(&s->kobj_remove_work, sysfs_slab_remove_workfn);
-
if (!kset) {
kobject_init(&s->kobj, &slab_ktype);
return 0;
@@ -5760,16 +5628,6 @@ static int sysfs_slab_add(struct kmem_cache *s)
if (err)
goto out_del_kobj;
-#ifdef CONFIG_MEMCG
- if (is_root_cache(s) && memcg_sysfs_enabled) {
- s->memcg_kset = kset_create_and_add("cgroup", NULL, &s->kobj);
- if (!s->memcg_kset) {
- err = -ENOMEM;
- goto out_del_kobj;
- }
- }
-#endif
-
if (!unmergeable) {
/* Setup first alias */
sysfs_slab_alias(s, s->name);
@@ -5783,19 +5641,6 @@ out_del_kobj:
goto out;
}
-static void sysfs_slab_remove(struct kmem_cache *s)
-{
- if (slab_state < FULL)
- /*
- * Sysfs has not been setup yet so no need to remove the
- * cache from sysfs.
- */
- return;
-
- kobject_get(&s->kobj);
- schedule_work(&s->kobj_remove_work);
-}
-
void sysfs_slab_unlink(struct kmem_cache *s)
{
if (slab_state >= FULL)