From nobody Mon Feb 9 08:05:35 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9366AC77B7C for ; Wed, 24 May 2023 06:57:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239692AbjEXG4q (ORCPT ); Wed, 24 May 2023 02:56:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41202 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239212AbjEXG4V (ORCPT ); Wed, 24 May 2023 02:56:21 -0400 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AB39BE71; Tue, 23 May 2023 23:55:46 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.30.67.153]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4QR25B1jLzz4f3kpy; Wed, 24 May 2023 14:55:42 +0800 (CST) Received: from ubuntu1804.huawei.com (unknown [10.67.174.58]) by APP4 (Coremail) with SMTP id gCh0CgCnD7PvtG1k22hiKA--.7544S4; Wed, 24 May 2023 14:55:43 +0800 (CST) From: Xiu Jianfeng To: tj@kernel.org, lizefan.x@bytedance.com, hannes@cmpxchg.org Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH -next v2] cgroup: Update out-of-date comment in cgroup_migrate() Date: Wed, 24 May 2023 14:54:31 +0800 Message-Id: <20230524065431.145434-1-xiujianfeng@huaweicloud.com> X-Mailer: git-send-email 2.17.1 X-CM-TRANSID: gCh0CgCnD7PvtG1k22hiKA--.7544S4 X-Coremail-Antispam: 1UD129KBjvJXoW7Wr43Cr1rWry3Jr1rtw43Wrg_yoW8Jry3pr ykJ345K345u3Wqvw1UCas29ryfC3yFgF47t39xXwsayr13Jw1YgFy0ka13Zr1YvF4IkF47 tFWYva9YkFyqyaDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUgCb4IE77IF4wAFF20E14v26r4j6ryUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6r1S6rWUM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x 0267AKxVW0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG 6I80ewAv7VC0I7IYx2IY67AKxVWUXVWUAwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFV Cjc4AY6r1j6r4UM4x0Y48IcxkI7VAKI48JMxAIw28IcxkI7VAKI48JMxC20s026xCaFVCj c4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4 CE17CEb7AF67AKxVWUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1x MIIF0xvE2Ix0cI8IcVCY1x0267AKxVWUJVW8JwCI42IY6xAIw20EY4v20xvaj40_Zr0_Wr 1UMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Jr0_GrUvcSsG vfC2KfnxnUUI43ZEXa7IU189N3UUUUU== X-CM-SenderInfo: x0lxyxpdqiv03j6k3tpzhluzxrxghudrp/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Commit 674b745e22b3 ("cgroup: remove rcu_read_lock()/rcu_read_unlock() in critical section of spin_lock_irq()") has removed the rcu_read_lock, which makes the comment out-of-date, so update it. Signed-off-by: Xiu Jianfeng --- v2: don't remove the comment, just update it. --- kernel/cgroup/cgroup.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index d8ba2c67910d..f10cef511ffa 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -2872,9 +2872,11 @@ int cgroup_migrate(struct task_struct *leader, bool = threadgroup, struct task_struct *task; =20 /* - * Prevent freeing of tasks while we take a snapshot. Tasks that are - * already PF_EXITING could be freed from underneath us unless we - * take an rcu_read_lock. + * We should take an rcu_read_lock to prevent freeing of tasks while + * taking a snapshot, because tasks that are already PF_EXITING could + * be freed when traversing all threads of leader. However rcu_read_lock + * which disable preempt is implied by the spin_lock_irq, so no explicit + * rcu call here. */ spin_lock_irq(&css_set_lock); task =3D leader; --=20 2.17.1