linux-kernel - [RFC PATCH] sched: Do not copy user_cpus_ptr when parent is reset_on

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Message-ID: <20240905090458.1173-1-xuewen.yan@unisoc.com>
Date: Thu, 5 Sep 2024 17:04:58 +0800
From: Xuewen Yan <xuewen.yan@...soc.com>
To: <mingo@...hat.com>, <peterz@...radead.org>, <juri.lelli@...hat.com>,
        <vincent.guittot@...aro.org>, <longman@...hat.com>
CC: <dietmar.eggemann@....com>, <rostedt@...dmis.org>, <bsegall@...gle.com>,
        <mgorman@...e.de>, <vschneid@...hat.com>,
        <linux-kernel@...r.kernel.org>, <ke.wang@...soc.com>,
        <di.shen@...soc.com>, <xuewen.yan94@...il.com>
Subject: [RFC PATCH] sched: Do not copy user_cpus_ptr when parent is reset_on_fork

Now, the task's user_cpus_ptr would dup from parent's user_cpus_ptr.
It is better reset the user_cpus_ptr when parent's reset_on_fork
is set.

Signed-off-by: Xuewen Yan <xuewen.yan@...soc.com>
---
 kernel/sched/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f3951e4a55e5..2fbae00cd1dc 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2666,7 +2666,7 @@ int dup_user_cpus_ptr(struct task_struct *dst, struct task_struct *src,
 	 * do_set_cpus_allowed().
 	 */
 	raw_spin_lock_irqsave(&src->pi_lock, flags);
-	if (src->user_cpus_ptr) {
+	if (src->user_cpus_ptr && !src->sched_reset_on_fork) {
 		swap(dst->user_cpus_ptr, user_mask);
 		cpumask_copy(dst->user_cpus_ptr, src->user_cpus_ptr);
 	}
-- 
2.25.1