linux-kernel - [PATCH v5 2/5] exit: hoist get_pid() in release_task() outside of tasklist

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Message-ID: <20250205200929.406568-3-mjguzik@gmail.com>
Date: Wed,  5 Feb 2025 21:09:26 +0100
From: Mateusz Guzik <mjguzik@...il.com>
To: ebiederm@...ssion.com,
	oleg@...hat.com
Cc: brauner@...nel.org,
	akpm@...ux-foundation.org,
	Liam.Howlett@...cle.com,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Mateusz Guzik <mjguzik@...il.com>
Subject: [PATCH v5 2/5] exit: hoist get_pid() in release_task() outside of tasklist_lock

reduces hold time as get_pid() contains an atomic

Reviewed-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Mateusz Guzik <mjguzik@...il.com>
---
 kernel/exit.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/exit.c b/kernel/exit.c
index c79b41509cd3..b5c0cbc6bdfb 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -248,9 +248,10 @@ void release_task(struct task_struct *p)
 
 	cgroup_release(p);
 
+	thread_pid = get_pid(p->thread_pid);
+
 	write_lock_irq(&tasklist_lock);
 	ptrace_release_task(p);
-	thread_pid = get_pid(p->thread_pid);
 	__exit_signal(p);
 
 	/*
-- 
2.43.0