The function workingset_activation() is called from
folio_mark_accessed() with the guarantee that the given folio can not be
freed under us in workingset_activation(). In addition, the association
of the folio and its memcg can not be broken here because charge
migration is no more. There is no need to use folio_memcg_rcu. Simply
use folio_memcg_charged() because that is what this function cares
about.
Signed-off-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Suggested-by: Yu Zhao <yuzhao@xxxxxxxxxx>
---
Andrew, please put this patch after charge migration deprecation series.
Changes since v1:
- Fix for mem_cgroup_disabled(). (Yu Zhao)
include/linux/memcontrol.h | 35 -----------------------------------
mm/workingset.c | 14 ++------------
2 files changed, 2 insertions(+), 47 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 932534291ca2..89a1e9f10e1b 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -443,35 +443,6 @@ static inline bool folio_memcg_charged(struct folio *folio)
return __folio_memcg(folio) != NULL;
}
-/**
- * folio_memcg_rcu - Locklessly get the memory cgroup associated with a folio.
- * @folio: Pointer to the folio.
- *
- * This function assumes that the folio is known to have a
- * proper memory cgroup pointer. It's not safe to call this function
- * against some type of folios, e.g. slab folios or ex-slab folios.
- *
- * Return: A pointer to the memory cgroup associated with the folio,
- * or NULL.
- */
-static inline struct mem_cgroup *folio_memcg_rcu(struct folio *folio)
-{
- unsigned long memcg_data = READ_ONCE(folio->memcg_data);
-
- VM_BUG_ON_FOLIO(folio_test_slab(folio), folio);
-
- if (memcg_data & MEMCG_DATA_KMEM) {
- struct obj_cgroup *objcg;
-
- objcg = (void *)(memcg_data & ~OBJEXTS_FLAGS_MASK);
- return obj_cgroup_memcg(objcg);
- }
-
- WARN_ON_ONCE(!rcu_read_lock_held());
-
- return (struct mem_cgroup *)(memcg_data & ~OBJEXTS_FLAGS_MASK);
-}
-
/*
* folio_memcg_check - Get the memory cgroup associated with a folio.
* @folio: Pointer to the folio.
@@ -1084,12 +1055,6 @@ static inline struct mem_cgroup *folio_memcg(struct folio *folio)
return NULL;
}
-static inline struct mem_cgroup *folio_memcg_rcu(struct folio *folio)
-{
- WARN_ON_ONCE(!rcu_read_lock_held());
- return NULL;
-}
-
static inline struct mem_cgroup *folio_memcg_check(struct folio *folio)
{
return NULL;
diff --git a/mm/workingset.c b/mm/workingset.c
index 4b58ef535a17..a4705e196545 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -591,22 +591,12 @@ void workingset_refault(struct folio *folio, void *shadow)
*/
void workingset_activation(struct folio *folio)
{
- struct mem_cgroup *memcg;
-
- rcu_read_lock();
/*
* Filter non-memcg pages here, e.g. unmap can call
* mark_page_accessed() on VDSO pages.
- *
- * XXX: See workingset_refault() - this should return
- * root_mem_cgroup even for !CONFIG_MEMCG.
*/
- memcg = folio_memcg_rcu(folio);
- if (!mem_cgroup_disabled() && !memcg)
- goto out;
- workingset_age_nonresident(folio_lruvec(folio), folio_nr_pages(folio));
-out:
- rcu_read_unlock();
+ if (mem_cgroup_disabled() || folio_memcg_charged(folio))
+ workingset_age_nonresident(folio_lruvec(folio), folio_nr_pages(folio));
}
/*
--
2.43.5
