[PATCH 5/8][SRU][OEM-5.17] mm/memcg: opencode the inner part of obj_cgroup_uncharge_pages() in drain_obj_stock()

[AceLan Kao]

From: Johannes Weiner <hannes at cmpxchg.org>

BugLink: https://launchpad.net/bugs/1990330

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 at linutronix.de: patch body around Johannes' diff]

Link: https://lkml.kernel.org/r/20220226204144.1008339-5-bigeasy@linutronix.de
Signed-off-by: Johannes Weiner <hannes at cmpxchg.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy at linutronix.de>
Reviewed-by: Shakeel Butt <shakeelb at google.com>
Reviewed-by: Roman Gushchin <guro at fb.com>
Acked-by: Michal Hocko <mhocko at suse.com>
Cc: kernel test robot <oliver.sang at intel.com>
Cc: Michal Hocko <mhocko at kernel.org>
Cc: Michal Koutný <mkoutny at suse.com>
Cc: Peter Zijlstra <peterz at infradead.org>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Vladimir Davydov <vdavydov.dev at gmail.com>
Cc: Waiman Long <longman at redhat.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
(cherry picked from commit af9a3b69e84bef996ce4620282fcf69a5786be3a)
Signed-off-by: Chia-Lin Kao (AceLan) <acelan.kao at canonical.com>
---
 mm/memcontrol.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2179c581a6a8..0c10ee59056b 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2269,12 +2269,9 @@ 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 */
@@ -2286,7 +2283,14 @@ 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);
 }
 
@@ -3203,8 +3207,16 @@ 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.
-- 
2.25.1