From nobody Tue Sep 9 16:21:03 2025 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) (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 2198F2DFA22; Sat, 6 Sep 2025 13:58:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.189 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757167142; cv=none; b=e98qEMJbqy46jIaRkqEcXoQoJL2wVxLilhftBk6MEyCRR3N8LIaZFR5S8/e8weLEsHhihobriuRav3tvPiG30AeRdfNr+rKremSyBZ6LnKoTBAuUIUvF42cQG8N2Fzm3c2inW+7b7hA1sBqZvUpuBLGs0pD2pqrkUlaD6HR+aG4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757167142; c=relaxed/simple; bh=IWDRX+XRiNczCWsdyqXh5uteSAcNl6psuD6Csmsl/Nk=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=oOETH6ojqGouKXpf8goO1YVyYx95JsLGR7yoCoE0HgYOQGdqZ8nLaQiAVQEF4nGyUcjOK1w5JTwzFXHhjlX8hmuiBn6gAimAhR4K9dFXIAnxcLMPldDoV8tGSnJxIOZV0DOI3XxuABKHJEMd51avY3itQl8l/vxrRudyFSVoimI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.189 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.162.254]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4cJvpS4nYQzJsZM; Sat, 6 Sep 2025 21:54:24 +0800 (CST) Received: from dggemv706-chm.china.huawei.com (unknown [10.3.19.33]) by mail.maildlp.com (Postfix) with ESMTPS id 64FAA18048F; Sat, 6 Sep 2025 21:58:55 +0800 (CST) Received: from kwepemn200010.china.huawei.com (7.202.194.133) by dggemv706-chm.china.huawei.com (10.3.19.33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Sat, 6 Sep 2025 21:58:55 +0800 Received: from huawei.com (10.44.142.84) by kwepemn200010.china.huawei.com (7.202.194.133) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Sat, 6 Sep 2025 21:58:54 +0800 From: Qi Xi To: , , , , , , , CC: Subject: [PATCH] once: fix race by moving DO_ONCE to separate section Date: Sat, 6 Sep 2025 21:49:34 +0800 Message-ID: <20250906134934.1739528-1-xiqi2@huawei.com> X-Mailer: git-send-email 2.33.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: kwepems500001.china.huawei.com (7.221.188.70) To kwepemn200010.china.huawei.com (7.202.194.133) Content-Type: text/plain; charset="utf-8" The commit c2c60ea37e5b ("once: use __section(".data.once")") moved DO_ONCE's ___done variable to .data.once section, which conflicts with WARN_ONCE series macros that also use the same section. This creates a race condition when clear_warn_once is used: Thread 1 (DO_ONCE) Thread 2 (DO_ONCE) __do_once_start read ___done (false) acquire once_lock execute func __do_once_done write ___done (true) __do_once_start release once_lock // Thread 3 clear_warn_once reset ___done read ___done (false) acquire once_lock execute func schedule once_work __do_once_done once_deferred: OK write ___done (true) static_branch_disable release once_lock schedule once_work once_deferred: BUG_ON(!static_key_enabled) Fix by moving DO_ONCE to separate .data..do_once section to avoid race conditions. Fixes: c2c60ea37e5b ("once: use __section(".data.once")") Reported-by: Hulk Robot Signed-off-by: Qi Xi --- include/asm-generic/vmlinux.lds.h | 1 + include/linux/once.h | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinu= x.lds.h index 883dbac79da9..94850b52e5cc 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -384,6 +384,7 @@ __start_once =3D .; \ *(.data..once) \ __end_once =3D .; \ + *(.data..do_once) \ STRUCT_ALIGN(); \ *(__tracepoints) \ /* implement dynamic printk debug */ \ diff --git a/include/linux/once.h b/include/linux/once.h index 30346fcdc799..261a7a4977dd 100644 --- a/include/linux/once.h +++ b/include/linux/once.h @@ -46,7 +46,7 @@ void __do_once_sleepable_done(bool *done, struct static_k= ey_true *once_key, #define DO_ONCE(func, ...) \ ({ \ bool ___ret =3D false; \ - static bool __section(".data..once") ___done =3D false; \ + static bool __section(".data..do_once") ___done =3D false; \ static DEFINE_STATIC_KEY_TRUE(___once_key); \ if (static_branch_unlikely(&___once_key)) { \ unsigned long ___flags; \ --=20 2.33.0