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.

[bigeasy@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@cmpxchg.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: kernel test robot <oliver.sang@intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index bc60694..00bedb9 100644 (file)
--- 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.