From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from va-2-57.ptr.blmpb.com (va-2-57.ptr.blmpb.com [209.127.231.57]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8A78735E936 for ; Mon, 3 Aug 2026 05:29:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.127.231.57 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785734990; cv=none; b=aOklwA7Y9tvPCv3Fshc9vzfEk3sYbGQtwZ8LeU+jlAcEjxJ/ssc+vR+VzlkMAGPHSl09/BPkxL6a8LPUw73c45q0+B+23anBiuP7hIeM3bR2rePAX0pLq0n64M43n0yllSrBSgi8/MRpvhXgwOSp5gBjlywdUtieiMLpkTIQk+0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785734990; c=relaxed/simple; bh=dyoyqsj+eOkgTGsz/UeO/4U0DhOjLi5FRzZXcY+CYm8=; h=To:Cc:Date:Content-Type:In-Reply-To:Message-Id:References:Subject: Mime-Version:From; b=blq4xVu0RV4UgFqUphzxNUy27oCdi9ROUzrUJiTPma7FiUBoCgR3Cx/jTjCgI2adZj294KQq4ary6wzpSjzj5gRdIgBda4O0pjsr6+FTtSoDDmCM5zR0UL6qZsdvrN+hogiJT3M1CgIRqOS4dzytYUAIUR/LrLEfBvayaQiT2ps= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=fnnas.com; spf=none smtp.mailfrom=fnnas.com; dkim=pass (2048-bit key) header.d=fnnas-com.20200927.dkim.feishu.cn header.i=@fnnas-com.20200927.dkim.feishu.cn header.b=g92Qq7M1; arc=none smtp.client-ip=209.127.231.57 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=fnnas.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=fnnas.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=fnnas-com.20200927.dkim.feishu.cn header.i=@fnnas-com.20200927.dkim.feishu.cn header.b="g92Qq7M1" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; s=s1; d=fnnas-com.20200927.dkim.feishu.cn; t=1785734980; h=from:subject:mime-version:from:date:message-id:subject:to:cc: reply-to:content-type:mime-version:in-reply-to:message-id; bh=Ral+m31fntqDDJ+VtdD1GL/ppOgGBjRGSzR99QpzVUQ=; b=g92Qq7M1S/KxpoW8Z1wr2POkVfk31cCOaZGAtc96Hyyy8+In5UQx4lLm7JxEGPgwsXNh26 GKIYNSHtDxZ4iQBqqgpHkwSAyF42PW9nKmz1d5UoeMXbvHCNzVpfE/erfKVrIBLqyk/zOC fjBWo9wkAQPEV2CqsedhTIsHAo3V/bnlwi+aRqq9Imbg9a5fMeYaW5eKrXaVx5S98u97Fj NBYz+0UwlMdIDehUPWlXyIj8/8Edo1A0JC7Z1//PkLSGarxuemHfRnqKnNaGKKD2wHOtnN 1CfGWs37CrrmX5TQUAouJbPlVJiUoaMLq7SUFKIDBl2oXIt0fOc79njWs44i8A== To: "Tao Cui" , , "yu kuai" Cc: , , , , , , "Tao Cui" Date: Mon, 3 Aug 2026 13:29:35 +0800 Received: from [192.168.1.104] ([39.182.0.181]) by smtp.feishu.cn with ESMTPS; Mon, 03 Aug 2026 13:29:37 +0800 Reply-To: yukuai@fygo.io Content-Type: text/plain; charset=UTF-8 X-Original-From: Yu Kuai Content-Transfer-Encoding: quoted-printable In-Reply-To: <20260802150413.29789-1-cui.tao@linux.dev> User-Agent: Mozilla Thunderbird Message-Id: <95905ed3-dc3f-410d-a530-e26724839d79@fnnas.com> References: <20260802150413.29789-1-cui.tao@linux.dev> Subject: Re: [PATCH] block/blk-cgroup-rwstat: use data_race() for online test Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Lms-Return-Path: From: "Yu Kuai" =E5=9C=A8 2026/8/2 23:04, Tao Cui =E5=86=99=E9=81=93: > From: Tao Cui > > blkg_rwstat_recursive_sum() reads pos_blkg->online without the queue > lock that its doc comment requires, since blkcg_print_blkgs() stopped > holding it in 56cc24f59c14. Concurrent blkg_create/destroy flips > ->online, tripping KCSAN. The race is harmless (RCU-protected, stale > online only causes minor stat noise). Use data_race() to annotate > the intentional lockless read. > > Signed-off-by: Tao Cui > --- > block/blk-cgroup-rwstat.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Reviewed-by: Yu Kuai --=20 Thanks, Kuai