linux-kernel - [PATCH v5 18/18] fork: Move thread_stack_free_rcu() to call_rcu

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Date:   Thu,  1 Sep 2022 22:17:20 +0000
From:   "Joel Fernandes (Google)" <joel@...lfernandes.org>
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, rushikesh.s.kadam@...el.com,
        urezki@...il.com, neeraj.iitr10@...il.com, frederic@...nel.org,
        paulmck@...nel.org, rostedt@...dmis.org, vineeth@...byteword.org,
        boqun.feng@...il.com,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>
Subject: [PATCH v5 18/18] fork: Move thread_stack_free_rcu() to call_rcu_lazy()

This is required to prevent callbacks triggering RCU machinery too
quickly and too often, which adds more power to the system.

Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
---
 kernel/fork.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 90c85b17bf69..08a2298b1f94 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -226,7 +226,7 @@ static void thread_stack_delayed_free(struct task_struct *tsk)
 	struct vm_stack *vm_stack = tsk->stack;
 
 	vm_stack->stack_vm_area = tsk->stack_vm_area;
-	call_rcu(&vm_stack->rcu, thread_stack_free_rcu);
+	call_rcu_lazy(&vm_stack->rcu, thread_stack_free_rcu);
 }
 
 static int free_vm_stack_cache(unsigned int cpu)
@@ -353,7 +353,7 @@ static void thread_stack_delayed_free(struct task_struct *tsk)
 {
 	struct rcu_head *rh = tsk->stack;
 
-	call_rcu(rh, thread_stack_free_rcu);
+	call_rcu_lazy(rh, thread_stack_free_rcu);
 }
 
 static int alloc_thread_stack_node(struct task_struct *tsk, int node)
@@ -388,7 +388,7 @@ static void thread_stack_delayed_free(struct task_struct *tsk)
 {
 	struct rcu_head *rh = tsk->stack;
 
-	call_rcu(rh, thread_stack_free_rcu);
+	call_rcu_lazy(rh, thread_stack_free_rcu);
 }
 
 static int alloc_thread_stack_node(struct task_struct *tsk, int node)
-- 
2.37.2.789.g6183377224-goog