There is no need to disable irqs to use objcg per-cpu stock, so let's
just not do that but consume_obj_stock() and refill_obj_stock() will
need to use trylock instead to keep per-cpu stock safe. One consequence
of this change is that the charge request from irq context may take
slowpath more often but it should be rare.
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
---
mm/memcontrol.c | 26 ++++++++++----------------
1 file changed, 10 insertions(+), 16 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index adf2f1922118..af7df675d733 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1918,18 +1918,17 @@ static void drain_local_memcg_stock(struct work_struct *dummy)
static void drain_local_obj_stock(struct work_struct *dummy)
{
struct obj_stock_pcp *stock;
- unsigned long flags;
if (WARN_ONCE(!in_task(), "drain in non-task context"))
return;
- local_lock_irqsave(&obj_stock.lock, flags);
+ local_lock(&obj_stock.lock);
stock = this_cpu_ptr(&obj_stock);
drain_obj_stock(stock);
clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags);
- local_unlock_irqrestore(&obj_stock.lock, flags);
+ local_unlock(&obj_stock.lock);
}
static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
@@ -2062,14 +2061,13 @@ void drain_all_stock(struct mem_cgroup *root_memcg)
static int memcg_hotplug_cpu_dead(unsigned int cpu)
{
struct obj_stock_pcp *obj_st;
- unsigned long flags;
obj_st = &per_cpu(obj_stock, cpu);
/* drain_obj_stock requires objstock.lock */
- local_lock_irqsave(&obj_stock.lock, flags);
+ local_lock(&obj_stock.lock);
drain_obj_stock(obj_st);
- local_unlock_irqrestore(&obj_stock.lock, flags);
+ local_unlock(&obj_stock.lock);
/* no need for the local lock */
drain_stock_fully(&per_cpu(memcg_stock, cpu));
@@ -2943,14 +2941,12 @@ static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes,
struct pglist_data *pgdat, enum node_stat_item idx)
{
struct obj_stock_pcp *stock;
- unsigned long flags;
bool ret = false;
- if (unlikely(in_nmi()))
+ if (unlikely(in_nmi()) ||
+ !local_trylock(&obj_stock.lock))
return ret;
- local_lock_irqsave(&obj_stock.lock, flags);
-
stock = this_cpu_ptr(&obj_stock);
if (objcg == READ_ONCE(stock->cached_objcg) && stock->nr_bytes >= nr_bytes) {
stock->nr_bytes -= nr_bytes;
@@ -2960,7 +2956,7 @@ static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes,
__account_obj_stock(objcg, stock, nr_bytes, pgdat, idx);
}
- local_unlock_irqrestore(&obj_stock.lock, flags);
+ local_unlock(&obj_stock.lock);
return ret;
}
@@ -3049,10 +3045,10 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes,
enum node_stat_item idx)
{
struct obj_stock_pcp *stock;
- unsigned long flags;
unsigned int nr_pages = 0;
- if (unlikely(in_nmi())) {
+ if (unlikely(in_nmi()) ||
+ !local_trylock(&obj_stock.lock)) {
if (pgdat)
mod_objcg_mlstate(objcg, pgdat, idx, nr_bytes);
nr_pages = nr_bytes >> PAGE_SHIFT;
@@ -3061,8 +3057,6 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes,
goto out;
}
- local_lock_irqsave(&obj_stock.lock, flags);
-
stock = this_cpu_ptr(&obj_stock);
if (READ_ONCE(stock->cached_objcg) != objcg) { /* reset if necessary */
drain_obj_stock(stock);
@@ -3083,7 +3077,7 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes,
stock->nr_bytes &= (PAGE_SIZE - 1);
}
- local_unlock_irqrestore(&obj_stock.lock, flags);
+ local_unlock(&obj_stock.lock);
out:
if (nr_pages)
obj_cgroup_uncharge_pages(objcg, nr_pages);
--
2.47.1