From 021a5ff8474379cd6c23e9b0e97aa27e5ff66a8b Mon Sep 17 00:00:00 2001
From: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Date: Tue, 11 Apr 2023 15:13:41 +0200
Subject: [PATCH] rcu/kvfree: Do not run a page work if a cache is disabled
By default the cache size is 5 pages per CPU, but it can be disabled at
boot time by setting the rcu_min_cached_objs to zero. When that happens,
the current code will uselessly set an hrtimer to schedule refilling this
cache with zero pages. This commit therefore streamlines this process
by simply refusing the set the hrtimer when rcu_min_cached_objs is zero.
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/tree.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 51d84eabf6453..18f592bf6dc61 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3225,6 +3225,10 @@ static void fill_page_cache_func(struct work_struct *work)
static void
run_page_cache_worker(struct kfree_rcu_cpu *krcp)
{
+ // If cache disabled, bail out.
+ if (!rcu_min_cached_objs)
+ return;
+
if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING &&
!atomic_xchg(&krcp->work_in_progress, 1)) {
if (atomic_read(&krcp->backoff_page_cache_fill)) {
--
2.30.2