From mboxrd@z Thu Jan 1 00:00:00 1970 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5FC28C54E58 for ; Thu, 21 Mar 2024 03:12:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EB1F16B0088; Wed, 20 Mar 2024 23:12:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E62566B0089; Wed, 20 Mar 2024 23:12:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D517E6B008A; Wed, 20 Mar 2024 23:12:36 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id C858B6B0088 for ; Wed, 20 Mar 2024 23:12:36 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 9B65A1A14D5 for ; Thu, 21 Mar 2024 03:12:36 +0000 (UTC) X-FDA: 81919573512.20.2D3C3DD Received: from out-176.mta1.migadu.com (out-176.mta1.migadu.com [95.215.58.176]) by imf21.hostedemail.com (Postfix) with ESMTP id B97AB1C0009 for ; Thu, 21 Mar 2024 03:12:34 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=dN2NPO+j; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf21.hostedemail.com: domain of chengming.zhou@linux.dev designates 95.215.58.176 as permitted sender) smtp.mailfrom=chengming.zhou@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1710990754; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=IkNEqpC4qw9eN2pRZI4l4aAjsLspOt5MnQaAsK4vE2s=; b=APB+TPQO94dzqgCowU4XFvNNz4WprJChAMbYkmYR01NsTOYSCUdSg4iEqiWP90O0MQrIwT ZHUEb/yir7Qeh0nkXdBxe+oyrXDoRqqGH/Vvv8XqDthlNznrkQaAb+jhg0uFu+fs2DY6i0 9lFKL7kxDJNzEo3NEXDsB1iVZALUn5w= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=dN2NPO+j; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf21.hostedemail.com: domain of chengming.zhou@linux.dev designates 95.215.58.176 as permitted sender) smtp.mailfrom=chengming.zhou@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1710990754; a=rsa-sha256; cv=none; b=AhnKtLMnX12uaUHs5tSHWKmazTTpGXe2/6YX1ImSYQ8JYiBZPZb8YiwIExBYhu5kL8aCP9 AVcOqb/FCCLLINbkQ4RI5EeD5Kl3+k7ce5Te8Wu5atiOkwOZEzlzqf+FvaLqgWOjJsNgup RrjhgW32W21FtLIWBY8l8NSOcGGXaYA= Message-ID: <62b4dd34-bf05-4da6-94ea-cb85ac48bbeb@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1710990746; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=IkNEqpC4qw9eN2pRZI4l4aAjsLspOt5MnQaAsK4vE2s=; b=dN2NPO+jnsoAfDnhNxR7Gfb8ObZXwpQU4qwsX4kVFYl/aTei8h6hfwAdvL1ptAM7a7/kqm UdppMg5so3r8sPH5/RaWjxQR7nMSqESQ93T/wy2JBPQ8eCpXArpUTED5yz+6TkGmvD69iG kguv3oPptq5ghx9zCI1OoyX0sErgPws= Date: Thu, 21 Mar 2024 11:12:20 +0800 MIME-Version: 1.0 Subject: Re: [PATCH] mm/slub: mark racy accesses on slab->slabs Content-Language: en-US To: linke li Cc: 42.hyeyoo@gmail.com, akpm@linux-foundation.org, cl@linux.com, iamjoonsoo.kim@lge.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, penberg@kernel.org, rientjes@google.com, roman.gushchin@linux.dev, vbabka@suse.cz References: <8bc1aebf-8395-416f-8c23-53cbd25d0eef@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Chengming Zhou In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: B97AB1C0009 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: u3abfbm93z3g5zofjxci1z59sso8c4fh X-HE-Tag: 1710990754-823765 X-HE-Meta: U2FsdGVkX182PUQbVFL199tU+5xmWfQD1nxsWJz4RCDMXJ99KPsIcnoAPzTgc2PiZxY6SGKWBuyA3kKVK+RFw9m4ayxiCYsqAy7bINM1PVpOmLj6aCcefGKzLei10RCFwR19CTnCXmcTeZ78UDxisb5/D34IDWtsIDWWOSl/2VDYfNhGd6ABk3KdqJ3ci49WtzpB2mjd9eWqoF2X2m6JLLZNS7V3wd3PZrdyUNwhq6QlYcjtY6MHEX1dRVg23aPTdnZh8rU2uR+lV0lSWHOpGvZlFJA0q1w4zC8JK0FcipOFPRYIupjGh1Hgl7bgGZv5/McrnUaCsRHMMHzdgs8qaQu7mKs8r8+8xas+GPP+lrNNgNRQtY+oLRsm1b7nr7pN7KcHhpHw2Sbr2Xjh6TYyVlpmlG9v0tff0b/5CeBJs3fdDvbZdZWyf5E94Ro3jgpiyam5Wa9PLUDTPX5jxeimy4qWJLFY+5lKHLckMLAoU0uQBesZOYFuyjI0yQluWKrZfAY0vvh+PRK9FgA/HnvCzlMioQHMI+ppKtNgSSOKyMguo9306W9hoMtBwnRSKsuxA4jq03KTJFEXPRyU8bcZ+FCvYvjr/6ilVds8kx/xoolmUfNQ7olcBtngOu1098NIN2YY0soFr/VC9Nrpc6FiD62pD9k2JKilhpMoaEKil18aCM8/Pjkdem2huUZ/8xJhXlU539g02QpNVPDOelSZMFIUPME0Qmv07O7s2wUHGuu5BMH5KL4PjlOhNBCtQnQPDeWDAR1TSXVx+BYNIM5qgsStXpu5Oxsqz0EKbxMmLsBa8r8iUNARRV3r1aiqlqTJrw4nmGday1N5HvCl8dPY8cHc2FwvnLDixwG2vsKeQpghFw/L4awRmkpBDoshzd/wm+sb9cnPZOzSfNKGPmtV2iRgO7x9JyQvyGTkfWCpr6R9rV0Pe7OZY5w9G8I7dcGV2ZAGyfOkGtAlUFOG0OF NHXDcUTJ 1Pey8RrP5OqPaPNEj1lF0CQnnGokmKhu2dx7o/xkZIG23VLWs8qMqjhSPinAVEq5IBKSvR4iHitWmoXsJlOlAenEU8FScuB3S+7kXnv2rtylwO03w+fNsKsNGARBBiZfRw1xB9z+L+bh0djYsZkee6al4k0bxGGXudyUGMmqBX8MubCGZiz8LYJ35O59oTmfOpccObk7H5FYlLinNtYtxlgvELMd3tSymoVw8WpxeIkInyIQlfL8f/rcG6A== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2024/3/21 10:48, linke li wrote: > Sorry for a late reply, I just found this because of my bad email client. > >> There is another unmarked access of "slab->slabs" in the show_slab_objects(), >> which you can change too. > > Yes, I think show_slab_objects() has a similar situation. Should I > consider to submit a V2 patch for this? Yes, I think so. > >> I'm not sure that it's really safe to access "slab->slabs" here without any protection? >> Although it should be no problem in practice, alternative choice maybe putting partial >> slabs count in the kmem_cache_cpu struct. > > I think it is ok, because it seems that slab->slabs in slub_percpu_partial > and show_slab_objects() are just used for showing some infomation. > > I noticed Paul summarized some of these strategies in access-marking.txt[1] Ok, thanks. > > Quote from it: > > "Use of the data_race() Macro > ---------------------------- > > Here are some situations where data_race() should be used instead of > READ_ONCE() and WRITE_ONCE(): > > 1. Data-racy loads from shared variables whose values are used only > for diagnostic purposes. > > 2. Data-racy reads whose values are checked against marked reload. > > 3. Reads whose values feed into error-tolerant heuristics. > > 4. Writes setting values that feed into error-tolerant heuristics. > " > > Thanks, > Linke > > [1]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/memory-model/Documentation/access-marking.txt >