[PATCH v5 4/6] mm/memcg: Opencode the inner part of obj_cgroup_uncharge_pages() in drain_obj_stock()

Sebastian Andrzej Siewior
2022-02-26T20:41:42Z

From: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>

Provide the inner part of refill_stock() as __refill_stock() without
disabling interrupts. This eases the integration of local_lock_t where
recursive locking must be avoided.
Open code obj_cgroup_uncharge_pages() in drain_obj_stock() and use
__refill_stock(). The caller of drain_obj_stock() already disables
interrupts.

[bigeasy: Patch body around Johannes' diff ]

Signed-off-by: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Reviewed-by: Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Reviewed-by: Roman Gushchin <guro-b10kYP2dOMg@public.gmane.org>
Acked-by: Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org>
---
mm/memcontrol.c | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 238ea77aade5d..4d049b4691afd 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2251,12 +2251,9 @@ static void drain_local_stock(struct work_struct *dummy)
* Cache charges(val) to local per_cpu area.
* This will be consumed by consume_stock() function, later.
*/
-static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
+static void __refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
{
struct memcg_stock_pcp *stock;
- unsigned long flags;
-
- local_irq_save(flags);

stock = this_cpu_ptr(&memcg_stock);
if (stock->cached != memcg) { /* reset if necessary */
@@ -2268,7 +2265,14 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)

if (stock->nr_pages > MEMCG_CHARGE_BATCH)
drain_stock(stock);
+}

+static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ __refill_stock(memcg, nr_pages);
local_irq_restore(flags);
}

@@ -3185,8 +3189,16 @@ static void drain_obj_stock(struct memcg_stock_pcp *stock)
unsigned int nr_pages = stock->nr_bytes >> PAGE_SHIFT;
unsigned int nr_bytes = stock->nr_bytes & (PAGE_SIZE - 1);

- if (nr_pages)
- obj_cgroup_uncharge_pages(old, nr_pages);
+ if (nr_pages) {
+ struct mem_cgroup *memcg;
+
+ memcg = get_mem_cgroup_from_objcg(old);
+
+ memcg_account_kmem(memcg, -nr_pages);
+ __refill_stock(memcg, nr_pages);
+
+ css_put(&memcg->css);
+ }

/*
* The leftover is flushed to the centralized per-memcg value.
--
2.35.1