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 66709C43334 for ; Tue, 28 Jun 2022 01:57:08 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F0AE48E0002; Mon, 27 Jun 2022 21:57:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EBAEE8E0001; Mon, 27 Jun 2022 21:57:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D82998E0002; Mon, 27 Jun 2022 21:57:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id C9FEF8E0001 for ; Mon, 27 Jun 2022 21:57:07 -0400 (EDT) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id A0E7C2119C for ; Tue, 28 Jun 2022 01:57:07 +0000 (UTC) X-FDA: 79625981694.19.F64A182 Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by imf31.hostedemail.com (Postfix) with ESMTP id EEFE92000F for ; Tue, 28 Jun 2022 01:57:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1656381426; x=1687917426; h=from:to:cc:subject:references:date:in-reply-to: message-id:mime-version; bh=KhNIX1vdfNA11IMZRMjDJRfMks3in0mWikfrfge0Psw=; b=YOrM7y4Qb9NuwaxG9YleuhHz1c0GeiZ7l1VuHYWjT3fE3XUwcoZiKHa0 pkgwIWwf88VqHO7FCr+Cjwl6ZYk7Yw8dz6kJPX8Pn+UUJ0ebOG2XD5v+y c+v8l6P1uLHrHiMZ62IEKI04s4Ic8F5K+UgtkvvQEJBPW5T2iK6ICqr1d wf6FbJE4mNlp0fxLzVlD25recTYDios6HuDFHgp115ZeDiBT11ApVXDj1 k/EY717xbzWqQUlStBTetm2MjcHdUwSL8qxizb/Dmp//U0vGtFJy+SdNb r5/HxJSZ4mMAxcIn+sVEBfSzQw9XQHKXSc6UXHrzVGBW4T8wahHfKETvB Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10391"; a="345606425" X-IronPort-AV: E=Sophos;i="5.92,227,1650956400"; d="scan'208";a="345606425" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jun 2022 18:57:04 -0700 X-IronPort-AV: E=Sophos;i="5.92,227,1650956400"; d="scan'208";a="692881407" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.239.13.94]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jun 2022 18:57:02 -0700 From: "Huang, Ying" To: Qian Cai Cc: Miaohe Lin , , , , , Subject: Re: [PATCH v3 1/2] mm/swapfile: fix possible data races of inuse_pages References: <20220625093346.48894-1-linmiaohe@huawei.com> <20220625093346.48894-2-linmiaohe@huawei.com> Date: Tue, 28 Jun 2022 09:56:58 +0800 In-Reply-To: (Qian Cai's message of "Mon, 27 Jun 2022 09:47:16 -0400") Message-ID: <874k057dp1.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii ARC-Authentication-Results: i=1; imf31.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=YOrM7y4Q; dmarc=pass (policy=none) header.from=intel.com; spf=none (imf31.hostedemail.com: domain of ying.huang@intel.com has no SPF policy when checking 134.134.136.100) smtp.mailfrom=ying.huang@intel.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1656381426; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=RRUQArDRdq8cbD+GIUA7N05b3UciN8l8gkjW8r/i47Y=; b=4zHSsPZghlVDq3tyc2ngB1cX4qkJT/8cy1RhCCJGmDOkAkzWypB6fPJEeayKy/5GXFmvF1 RSPUxRsy7iqsjH/Hc0Mn6q+YcOQ4tzM6gqFB8oCNjGTAvRzwya9JpoxSkp8JmTvU1/eU8T ZS8s9dZs9M8+6bsLb0U2DWpG1j2smH8= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1656381426; a=rsa-sha256; cv=none; b=FxTOGyLJFLhrkiOqNZikghOaB95u1b2JEfNy4Gb+eGZCqDxdPsbBXYFmMQxafpqm49WhSt 393CxVBQAGhKJ0fDZDpCaeLIyQrALuGUzJvRlePMdo6dpxvwQjCBEDhdGWDGDtQNa20wvk uzX3CvU2c9PDapWvO5orTFgFsebIsEQ= X-Stat-Signature: yqcb9psay5w51yt3kgixizotcyufzq4f X-Rspamd-Queue-Id: EEFE92000F Authentication-Results: imf31.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=YOrM7y4Q; dmarc=pass (policy=none) header.from=intel.com; spf=none (imf31.hostedemail.com: domain of ying.huang@intel.com has no SPF policy when checking 134.134.136.100) smtp.mailfrom=ying.huang@intel.com X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1656381425-225385 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: Qian Cai writes: > On Mon, Jun 27, 2022 at 09:27:43PM +0800, Miaohe Lin wrote: >> On 2022/6/27 20:43, Qian Cai wrote: >> > On Sat, Jun 25, 2022 at 05:33:45PM +0800, Miaohe Lin wrote: >> >> si->inuse_pages could still be accessed concurrently now. The plain reads >> >> outside si->lock critical section, i.e. swap_show and si_swapinfo, which >> >> results in data races. READ_ONCE and WRITE_ONCE is used to fix such data >> >> races. Note these data races should be ok because they're just used for >> >> showing swap info. >> > >> > Was this found by kcsan? If so, it would be useful to record the exact >> > kscan report in the commit message. >> >> Sorry, it's found via code inspection. > > Well, if we are going to do a WRITE_ONCE() in those places just for > documentation purpose now, I think we will need to fix all places in the mm > subsystem to be consistent. We have already done this in swapfile.c, please search "WRITE_ONCE" in that file. Best Regards, Huang, Ying