2020-11-10 18:50:09

by Roman Gushchin

Subject: [PATCH] mm: memcg: fix obsolete code comments

This patch fixes/removes some obsolete comments in the code related
to the kernel memory accounting:
- kmem_cache->memcg_params.memcg_caches has been removed
by commit 9855609bde03 ("mm: memcg/slab: use a single set of
kmem_caches for all accounted allocations")
- memcg->kmemcg_id is not used as a gate for kmem accounting since
commit 0b8f73e10428 ("mm: memcontrol: clean up alloc, online,
offline, free functions")

Signed-off-by: Roman Gushchin <[email protected]>
---
include/linux/memcontrol.h | 6 ++----
mm/memcontrol.c | 6 ------
2 files changed, 2 insertions(+), 10 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 20108e426f84..01099dfa839c 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -310,7 +310,6 @@ struct mem_cgroup {
int tcpmem_pressure;

#ifdef CONFIG_MEMCG_KMEM
- /* Index in the kmem_cache->memcg_params.memcg_caches array */
int kmemcg_id;
enum memcg_kmem_state kmem_state;
struct obj_cgroup __rcu *objcg;
@@ -1641,9 +1640,8 @@ static inline void memcg_kmem_uncharge_page(struct page *page, int order)
}

/*
- * helper for accessing a memcg's index. It will be used as an index in the
- * child cache array in kmem_cache, and also to derive its name. This function
- * will return -1 when this is not a kmem-limited memcg.
+ * A helper for accessing memcg's kmem_id, used for getting
+ * corresponding LRU lists.
*/
static inline int memcg_cache_id(struct mem_cgroup *memcg)
{
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 69a2893a6455..62bbd48d8445 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3680,12 +3680,6 @@ static int memcg_online_kmem(struct mem_cgroup *memcg)

static_branch_enable(&memcg_kmem_enabled_key);

- /*
- * A memory cgroup is considered kmem-online as soon as it gets
- * kmemcg_id. Setting the id after enabling static branching will
- * guarantee no one starts accounting before all call sites are
- * patched.
- */
memcg->kmemcg_id = memcg_id;
memcg->kmem_state = KMEM_ONLINE;

--
2.26.2

2020-11-10 18:52:35

by Johannes Weiner

Subject: Re: [PATCH] mm: memcg: fix obsolete code comments

On Tue, Nov 10, 2020 at 10:46:15AM -0800, Roman Gushchin wrote:
> This patch fixes/removes some obsolete comments in the code related
> to the kernel memory accounting:
> - kmem_cache->memcg_params.memcg_caches has been removed
> by commit 9855609bde03 ("mm: memcg/slab: use a single set of
> kmem_caches for all accounted allocations")
> - memcg->kmemcg_id is not used as a gate for kmem accounting since
> commit 0b8f73e10428 ("mm: memcontrol: clean up alloc, online,
> offline, free functions")
>
> Signed-off-by: Roman Gushchin <[email protected]>

Acked-by: Johannes Weiner <[email protected]>

Thanks Roman

2020-11-10 19:03:15

by Shakeel Butt

Subject: Re: [PATCH] mm: memcg: fix obsolete code comments

On Tue, Nov 10, 2020 at 10:46 AM Roman Gushchin <[email protected]> wrote:
>
> This patch fixes/removes some obsolete comments in the code related
> to the kernel memory accounting:
> - kmem_cache->memcg_params.memcg_caches has been removed
> by commit 9855609bde03 ("mm: memcg/slab: use a single set of
> kmem_caches for all accounted allocations")
> - memcg->kmemcg_id is not used as a gate for kmem accounting since
> commit 0b8f73e10428 ("mm: memcontrol: clean up alloc, online,
> offline, free functions")
>
> Signed-off-by: Roman Gushchin <[email protected]>

Reviewed-by: Shakeel Butt <[email protected]>