[044/227] mm/memcg: opencode the inner part of obj_cgroup_uncharge_pages() in drain_obj_stock()

Commit Message

Andrew Morton March 22, 2022, 9:40 p.m. UTC

From: Johannes Weiner <[e-mail]>
Subject: mm/memcg: opencode the inner part of obj_cgroup_uncharge_pages() in drain_obj_stock()

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.

[[e-mail]: patch body around Johannes' diff]
Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Johannes Weiner <[e-mail]>
Signed-off-by: Sebastian Andrzej Siewior <[e-mail]>
Reviewed-by: Shakeel Butt <[e-mail]>
Reviewed-by: Roman Gushchin <[e-mail]>
Acked-by: Michal Hocko <[e-mail]>
Cc: kernel test robot <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Michal Koutný <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Vladimir Davydov <[e-mail]>
Cc: Waiman Long <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/memcontrol.c |   24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

Patch

--- a/mm/memcontrol.c~mm-memcg-opencode-the-inner-part-of-obj_cgroup_uncharge_pages-in-drain_obj_stock
+++ a/mm/memcontrol.c
@@ -2251,12 +2251,9 @@  static void drain_local_stock(struct wor
  * 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_cgro
 
 	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
 		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.