From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7FAF71F4606; Mon, 28 Jul 2025 02:55:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753671347; cv=none; b=tGVj6HlsI7T59s1/XLmuadB10ubY9XPOJA4WR+xz5CEEwLhWJNEJz7WNdoBu9IUnnDGve/vC/WoJ9XuL2st653WWNYE66SSSfOaHsgaEZs5GwYdE7L/c+Gvy9oaFH+bQ7CF/x5ZAbsAH8CpQbYMbpo3o96iOURQRAwwP24HcW2E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753671347; c=relaxed/simple; bh=k7f9xVVqnBIV5Abjt6ftreSV9DcoUd/iT8/KPTbL79k=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=WGtWeV3ZZyRBkYtSNPVCs6AbnxsBR3L1bILJBurnjNh4I0blcW/XKx1Z695A2JdCfWksGlZRqkc5Ni3xr5QgfXKA5vV4Gas//Z0XHnYg3S5L1gSTq8pGLY4nOaVZSyVsUtFW4KaO0GyoxBkotOIxzhvPSMsX1l+8FF6eqICcKgs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=none smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.216]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4br34p63d2zKHMgr; Mon, 28 Jul 2025 10:55:38 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id AAFF71A19F3; Mon, 28 Jul 2025 10:55:37 +0800 (CST) Received: from hulk-vt.huawei.com (unknown [10.67.174.121]) by APP4 (Coremail) with SMTP id gCh0CgDXng+W5oZohS7qBg--.25661S7; Mon, 28 Jul 2025 10:55:37 +0800 (CST) From: Chen Ridong To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, rafael@kernel.org, pavel@ucw.cz Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, lujialin4@huawei.com, chenridong@huawei.com Subject: [PATCH 6.6 5/5] sched,freezer: Remove unnecessary warning in __thaw_task Date: Mon, 28 Jul 2025 02:41:21 +0000 Message-Id: <20250728024121.33864-6-chenridong@huaweicloud.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250728024121.33864-1-chenridong@huaweicloud.com> References: <2025072421-deviate-skintight-bbd5@gregkh> <20250728024121.33864-1-chenridong@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:gCh0CgDXng+W5oZohS7qBg--.25661S7 X-Coremail-Antispam: 1UD129KBjvJXoW7Kr15JrykWFWrGF48Xr47Jwb_yoW5JFykpw s3Ww4xKr48tr1jyrWUJa10qFyDKan3Xw4UGrykGr18XF43XasYqrn7AryYg34jvrWIgry5 t3Z0gr40y3yDZ3JanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPSb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUAV Cq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0 rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVWDJVCq3wA2z4x0Y4vE2Ix0cI8IcVCY1x0267 AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E 14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7 xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Y z7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lc7CjxVAaw2 AFwI0_Jw0_GFyl42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAq x4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r4a6r W5MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_JFI_Gr1lIxAIcVC0I7IYx2IY6xkF 7I0E14v26F4j6r4UJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI 0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7I U1aLvJUUUUU== X-CM-SenderInfo: hfkh02xlgr0w46kxt4xhlfz01xgou0bp/ From: Chen Ridong [ Upstream commit 9beb8c5e77dc10e3889ff5f967eeffba78617a88 ] Commit cff5f49d433f ("cgroup_freezer: cgroup_freezing: Check if not frozen") modified the cgroup_freezing() logic to verify that the FROZEN flag is not set, affecting the return value of the freezing() function, in order to address a warning in __thaw_task. A race condition exists that may allow tasks to escape being frozen. The following scenario demonstrates this issue: CPU 0 (get_signal path) CPU 1 (freezer.state reader) try_to_freeze read freezer.state __refrigerator freezer_read update_if_frozen WRITE_ONCE(current->__state, TASK_FROZEN); ... /* Task is now marked frozen */ /* frozen(task) == true */ /* Assuming other tasks are frozen */ freezer->state |= CGROUP_FROZEN; /* freezing(current) returns false */ /* because cgroup is frozen (not freezing) */ break out __set_current_state(TASK_RUNNING); /* Bug: Task resumes running when it should remain frozen */ The existing !frozen(p) check in __thaw_task makes the WARN_ON_ONCE(freezing(p)) warning redundant. Removing this warning enables reverting commit cff5f49d433f ("cgroup_freezer: cgroup_freezing: Check if not frozen") to resolve the issue. This patch removes the warning from __thaw_task. A subsequent patch will revert commit cff5f49d433f ("cgroup_freezer: cgroup_freezing: Check if not frozen") to complete the fix. Reported-by: Zhong Jiawei Signed-off-by: Chen Ridong Signed-off-by: Tejun Heo --- kernel/freezer.c | 15 +++------------ 1 file changed, 3 insertions(+), 12 deletions(-) diff --git a/kernel/freezer.c b/kernel/freezer.c index f57aaf96b829..d8db479af478 100644 --- a/kernel/freezer.c +++ b/kernel/freezer.c @@ -196,18 +196,9 @@ static int __restore_freezer_state(struct task_struct *p, void *arg) void __thaw_task(struct task_struct *p) { - unsigned long flags; - - spin_lock_irqsave(&freezer_lock, flags); - if (WARN_ON_ONCE(freezing(p))) - goto unlock; - - if (!frozen(p) || task_call_func(p, __restore_freezer_state, NULL)) - goto unlock; - - wake_up_state(p, TASK_FROZEN); -unlock: - spin_unlock_irqrestore(&freezer_lock, flags); + guard(spinlock_irqsave)(&freezer_lock); + if (frozen(p) && !task_call_func(p, __restore_freezer_state, NULL)) + wake_up_state(p, TASK_FROZEN); } /** -- 2.34.1