[RFC PATCH 09/10] memcg: trylock stock for objcg

From: Shakeel Butt
Date: Fri Mar 14 2025 - 02:17:44 EST


To make objcg stock functions work without disabling irq, we need to
convert those function to use localtry_trylock_irqsave() instead of
localtry_lock_irqsave(). This patch for now just does the conversion and
later patch will eliminate the irq disabling code.

Signed-off-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
---
mm/memcontrol.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c803d2f5e322..ba5d004049d3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2764,7 +2764,11 @@ static void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat,
unsigned long flags;
int *bytes;

- localtry_lock_irqsave(&memcg_stock.stock_lock, flags);
+ if (!localtry_trylock_irqsave(&memcg_stock.stock_lock, flags)) {
+ __mod_objcg_mlstate(objcg, pgdat, idx, nr);
+ return;
+ }
+
stock = this_cpu_ptr(&memcg_stock);

/*
@@ -2822,7 +2826,8 @@ static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes)
unsigned long flags;
bool ret = false;

- localtry_lock_irqsave(&memcg_stock.stock_lock, flags);
+ if (!localtry_trylock_irqsave(&memcg_stock.stock_lock, flags))
+ return ret;

stock = this_cpu_ptr(&memcg_stock);
if (objcg == READ_ONCE(stock->cached_objcg) && stock->nr_bytes >= nr_bytes) {
@@ -2918,7 +2923,10 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes,
unsigned long flags;
unsigned int nr_pages = 0;

- localtry_lock_irqsave(&memcg_stock.stock_lock, flags);
+ if (!localtry_trylock_irqsave(&memcg_stock.stock_lock, flags)) {
+ atomic_add(nr_bytes, &objcg->nr_charged_bytes);
+ return;
+ }

stock = this_cpu_ptr(&memcg_stock);
if (READ_ONCE(stock->cached_objcg) != objcg) { /* reset if necessary */
--
2.47.1