From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 0C8BA2EA739; Tue, 22 Jul 2025 14:15:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753193738; cv=none; b=XhBhcAAqDUugkQVZ73qkYyDNybmxtlhOWrBEuZ8fnC44L5C9Rb8cylLwIm2Lfs+L1lbLPKv3/sgDDPa46ssVhQ5rnHxy8GGkE+BsYDnJtHk3EiNUHP5RzklEWg8HSUp8pLL/RQM65xqIc8MMw5Cs6DZFfsmtjRIx32NV61Ijg1M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753193738; c=relaxed/simple; bh=e6CjX2c7bSjxb8D2qfHaPYquCltjelwW8dqyndRsbMg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WGdeUi/4/j4pFhNnUEHhqGPjALAtcjONsjZUzw/Rh8aWdZ+wCsmCtCCeD1qkNmOF+vObU14ZsqSA0pWHQ/33dBy9VNFoqDmND+rShRe8V32Cdmblk956BzQCzNEUOBKZyQKvudt+XlDKOMgd6kTEFwDgTgP7iq61ccG2qFp2r+o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=cISrMAvR; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="cISrMAvR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73A7FC4CEEB; Tue, 22 Jul 2025 14:15:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1753193737; bh=e6CjX2c7bSjxb8D2qfHaPYquCltjelwW8dqyndRsbMg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cISrMAvRNcF/AqiDRqMB8a3HD1BeT7x0g+ovW8ihxuM6z+Qvzk4EGUhT5mVi1MadJ MLWv0ebz9oKDfGJrT0dqKyvoCruwI/azCG4GDFcvS46++LXkwyFGWBC7YSIhxsVlag hGWRQcINTX/qPYTD3+yufHLyku0svTtvM/BOXji8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Zhong Jiawei , Chen Ridong , Tejun Heo Subject: [PATCH 6.15 183/187] sched,freezer: Remove unnecessary warning in __thaw_task Date: Tue, 22 Jul 2025 15:45:53 +0200 Message-ID: <20250722134352.585987270@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250722134345.761035548@linuxfoundation.org> References: <20250722134345.761035548@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chen Ridong commit 9beb8c5e77dc10e3889ff5f967eeffba78617a88 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- kernel/freezer.c | 15 +++------------ 1 file changed, 3 insertions(+), 12 deletions(-) --- a/kernel/freezer.c +++ b/kernel/freezer.c @@ -201,18 +201,9 @@ static int __restore_freezer_state(struc 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); } /**