mm: kmem: cleanup (__)memcg_kmem_charge_memcg() arguments

Patch series "mm: memcg: kmem API cleanup", v2.

This patchset aims to clean up the kernel memory charging API.  It doesn't
bring any functional changes, just removes unused arguments, renames some
functions and fixes some comments.

Currently it's not obvious which functions are most basic
(memcg_kmem_(un)charge_memcg()) and which are based on them
(memcg_kmem_(un)charge()).  The patchset renames these functions and
removes unused arguments:

TL;DR:
was:
  memcg_kmem_charge_memcg(page, gfp, order, memcg)
  memcg_kmem_uncharge_memcg(memcg, nr_pages)
  memcg_kmem_charge(page, gfp, order)
  memcg_kmem_uncharge(page, order)

now:
  memcg_kmem_charge(memcg, gfp, nr_pages)
  memcg_kmem_uncharge(memcg, nr_pages)
  memcg_kmem_charge_page(page, gfp, order)
  memcg_kmem_uncharge_page(page, order)

This patch (of 6):

The first argument of memcg_kmem_charge_memcg() and
__memcg_kmem_charge_memcg() is the page pointer and it's not used.  Let's
drop it.

Memcg pointer is passed as the last argument.  Move it to the first place
for consistency with other memcg functions, e.g.
__memcg_kmem_uncharge_memcg() or try_charge().

Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Link: http://lkml.kernel.org/r/20200109202659.752357-2-guro@fb.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index e9ba01336d4e72e4e56778be4b0f7e652683054d..f1542d6558c2c64fec4804a4bf07e2e1817a7280 100644 (file)
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1369,8 +1369,7 @@ void memcg_kmem_put_cache(struct kmem_cache *cachep);
 #ifdef CONFIG_MEMCG_KMEM
 int __memcg_kmem_charge(struct page *page, gfp_t gfp, int order);
 void __memcg_kmem_uncharge(struct page *page, int order);
-int __memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order,
-                             struct mem_cgroup *memcg);
+int __memcg_kmem_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp, int order);
 void __memcg_kmem_uncharge_memcg(struct mem_cgroup *memcg,
                                 unsigned int nr_pages);
 
@@ -1407,11 +1406,11 @@ static inline void memcg_kmem_uncharge(struct page *page, int order)
                __memcg_kmem_uncharge(page, order);
 }
 
-static inline int memcg_kmem_charge_memcg(struct page *page, gfp_t gfp,
-                                         int order, struct mem_cgroup *memcg)
+static inline int memcg_kmem_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp,
+                                         int order)
 {
        if (memcg_kmem_enabled())
-               return __memcg_kmem_charge_memcg(page, gfp, order, memcg);
+               return __memcg_kmem_charge_memcg(memcg, gfp, order);
        return 0;
 }
 

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c1aa24a57e55713d327353d7b95ae8f542469bcb..896b6ebef6a26094621c422f2cc44ac1ef3b4359 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2882,15 +2882,13 @@ void memcg_kmem_put_cache(struct kmem_cache *cachep)
 
 /**
  * __memcg_kmem_charge_memcg: charge a kmem page
- * @page: page to charge
+ * @memcg: memory cgroup to charge
  * @gfp: reclaim mode
  * @order: allocation order
- * @memcg: memory cgroup to charge
  *
  * Returns 0 on success, an error code on failure.
  */
-int __memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order,
-                           struct mem_cgroup *memcg)
+int __memcg_kmem_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp, int order)
 {
        unsigned int nr_pages = 1 << order;
        struct page_counter *counter;
@@ -2936,7 +2934,7 @@ int __memcg_kmem_charge(struct page *page, gfp_t gfp, int order)
 
        memcg = get_mem_cgroup_from_current();
        if (!mem_cgroup_is_root(memcg)) {
-               ret = __memcg_kmem_charge_memcg(page, gfp, order, memcg);
+               ret = __memcg_kmem_charge_memcg(memcg, gfp, order);
                if (!ret) {
                        page->mem_cgroup = memcg;
                        __SetPageKmemcg(page);

diff --git a/mm/slab.h b/mm/slab.h
index 7e94700aa78c6e4fd9f26dcfa559688a7920fc3f..c4c93e991250d5fc1eed9f8655a7b577596c13f7 100644 (file)
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -365,7 +365,7 @@ static __always_inline int memcg_charge_slab(struct page *page,
                return 0;
        }
 
-       ret = memcg_kmem_charge_memcg(page, gfp, order, memcg);
+       ret = memcg_kmem_charge_memcg(memcg, gfp, order);
        if (ret)
                goto out;