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 BDCDCC433F5 for ; Mon, 31 Jan 2022 23:43:44 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2A3A88D0035; Mon, 31 Jan 2022 18:43:44 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 251E28D0028; Mon, 31 Jan 2022 18:43:44 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 11B658D0035; Mon, 31 Jan 2022 18:43:44 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0138.hostedemail.com [216.40.44.138]) by kanga.kvack.org (Postfix) with ESMTP id 04A788D0028 for ; Mon, 31 Jan 2022 18:43:44 -0500 (EST) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id A816699915 for ; Mon, 31 Jan 2022 23:43:43 +0000 (UTC) X-FDA: 79092211926.06.E4ECFE9 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf23.hostedemail.com (Postfix) with ESMTP id 45B2C140003 for ; Mon, 31 Jan 2022 23:43:43 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2283A60C26; Mon, 31 Jan 2022 23:43:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 42617C340EC; Mon, 31 Jan 2022 23:43:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1643672621; bh=7F7rGKin8kFBYulVUr3maZBnBl+p1ysUFkm3zq518Yw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=MpkeaLQThVMk9vfPEzYRm/b8NRdBh0k8KXiVDsoGl55i8Fno7JreuLashX0g3BiT8 16BteH0eL9Cf0ibNod1n9oxCLFPYLIX7y+6JqTIN9vOZylB+9cwUpYvaQB+0xVA0yC ZCYLbqvvY8nBKRA6PhqnHJkgXU8NTH/2QtS/y8CY= Date: Mon, 31 Jan 2022 15:43:40 -0800 From: Andrew Morton To: Mauricio Faria de Oliveira Cc: Minchan Kim , "Huang, Ying" , Yu Zhao , Yang Shi , Miaohe Lin , linux-mm@kvack.org, linux-block@vger.kernel.org Subject: Re: [PATCH v3] mm: fix race between MADV_FREE reclaim and blkdev direct IO read Message-Id: <20220131154340.e65ebe932d8933bc68c4ddf4@linux-foundation.org> In-Reply-To: <20220131230255.789059-1-mfo@canonical.com> References: <20220131230255.789059-1-mfo@canonical.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 45B2C140003 X-Stat-Signature: 3xsr7o37xs1puqxf4jicgwwt3phbdtei Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=MpkeaLQT; dmarc=none; spf=pass (imf23.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Rspam-User: nil X-HE-Tag: 1643672623-196079 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: On Mon, 31 Jan 2022 20:02:55 -0300 Mauricio Faria de Oliveira wrote: > Problem: > ======= > > Userspace might read the zero-page instead of actual data from a > direct IO read on a block device if the buffers have been called > madvise(MADV_FREE) on earlier (this is discussed below) due to a > race between page reclaim on MADV_FREE and blkdev direct IO read. > > ... > > Fixes: 802a3a92ad7a ("mm: reclaim MADV_FREE pages") Five years ago. As it doesn't seem urgent I targeted 5.18-rc1 for this, and added a cc:stable so it will trickle back into earlier trees. How does this plan sound?