[patch 075/163] mm: memcg/slab: remove memcg_kmem_get_cache()

Andrew Morton
2020-08-07T06:21:20Z

From: Roman Gushchin <guro@fb.com>
Subject: mm: memcg/slab: remove memcg_kmem_get_cache()

The memcg_kmem_get_cache() function became really trivial, so let's just
inline it into the single call point: memcg_slab_pre_alloc_hook().

It will make the code less bulky and can also help the compiler to
generate a better code.

Link: http://lkml.kernel.org/r/20200623174037.3951353-15-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

include/linux/memcontrol.h | 2 --
mm/memcontrol.c | 25 +------------------------
mm/slab.h | 11 +++++++++--
mm/slab_common.c | 2 +-
4 files changed, 11 insertions(+), 29 deletions(-)

--- a/include/linux/memcontrol.h~mm-memcg-slab-remove-memcg_kmem_get_cache
+++ a/include/linux/memcontrol.h
@@ -1403,8 +1403,6 @@ static inline void memcg_set_shrinker_bi
}
#endif

-struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep);
-
#ifdef CONFIG_MEMCG_KMEM
int __memcg_kmem_charge(struct mem_cgroup *memcg, gfp_t gfp,
unsigned int nr_pages);
--- a/mm/memcontrol.c~mm-memcg-slab-remove-memcg_kmem_get_cache
+++ a/mm/memcontrol.c
@@ -393,7 +393,7 @@ void memcg_put_cache_ids(void)

/*
* A lot of the calls to the cache allocation functions are expected to be
- * inlined by the compiler. Since the calls to memcg_kmem_get_cache are
+ * inlined by the compiler. Since the calls to memcg_slab_pre_alloc_hook() are
* 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
*/
@@ -2901,29 +2901,6 @@ static void memcg_free_cache_id(int id)
}

/**
- * memcg_kmem_get_cache: select memcg or root cache for allocation
- * @cachep: the original global kmem cache
- *
- * Return the kmem_cache we're supposed to use for a slab allocation.
- *
- * If the cache does not exist yet, if we are the first user of it, we
- * create it asynchronously in a workqueue and let the current allocation
- * go through with the original cache.
- */
-struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep)
-{
- struct kmem_cache *memcg_cachep;
-
- memcg_cachep = READ_ONCE(cachep->memcg_params.memcg_cache);
- if (unlikely(!memcg_cachep)) {
- queue_work(system_wq, &cachep->memcg_params.work);
- return cachep;
- }
-
- return memcg_cachep;
-}
-
-/**
* __memcg_kmem_charge: charge a number of kernel pages to a memcg
* @memcg: memory cgroup to charge
* @gfp: reclaim mode
--- a/mm/slab_common.c~mm-memcg-slab-remove-memcg_kmem_get_cache
+++ a/mm/slab_common.c
@@ -570,7 +570,7 @@ void memcg_create_kmem_cache(struct kmem
}

/*
- * Since readers won't lock (see memcg_kmem_get_cache()), we need a
+ * Since readers won't lock (see memcg_slab_pre_alloc_hook()), we need a
* barrier here to ensure nobody will see the kmem_cache partially
* initialized.
*/
--- a/mm/slab.h~mm-memcg-slab-remove-memcg_kmem_get_cache
+++ a/mm/slab.h
@@ -365,9 +365,16 @@ static inline struct kmem_cache *memcg_s
if (memcg_kmem_bypass())
return s;

- cachep = memcg_kmem_get_cache(s);
- if (is_root_cache(cachep))
+ cachep = READ_ONCE(s->memcg_params.memcg_cache);
+ if (unlikely(!cachep)) {
+ /*
+ * If memcg cache does not exist yet, we schedule it's
+ * asynchronous creation and let the current allocation
+ * go through with the root cache.
+ */
+ queue_work(system_wq, &s->memcg_params.work);
return s;
+ }

objcg = get_obj_cgroup_from_current();
if (!objcg)
_