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 X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76897C07E9C for ; Wed, 14 Jul 2021 05:28:47 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B13B861370 for ; Wed, 14 Jul 2021 05:28:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B13B861370 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D4CAE6B0088; Wed, 14 Jul 2021 01:28:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CFCDC6B008C; Wed, 14 Jul 2021 01:28:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BC47B6B0092; Wed, 14 Jul 2021 01:28:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0180.hostedemail.com [216.40.44.180]) by kanga.kvack.org (Postfix) with ESMTP id 932BD6B0088 for ; Wed, 14 Jul 2021 01:28:46 -0400 (EDT) Received: from smtpin38.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 8B1B11845142C for ; Wed, 14 Jul 2021 05:28:45 +0000 (UTC) X-FDA: 78360063810.38.7F89C56 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf06.hostedemail.com (Postfix) with ESMTP id 69A62801D3D7 for ; Wed, 14 Jul 2021 05:28:44 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id A429C67373; Wed, 14 Jul 2021 07:28:41 +0200 (CEST) Date: Wed, 14 Jul 2021 07:28:41 +0200 From: Christoph Hellwig To: Andrew Morton Cc: Christoph Hellwig , Ira Weiny , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/2] mm: call flush_dcache_page in memcpy_to_page and memzero_page Message-ID: <20210714052841.GA6380@lst.de> References: <20210713055231.137602-1-hch@lst.de> <20210713055231.137602-2-hch@lst.de> <20210713183123.699769a1b0ee95d69606c35d@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210713183123.699769a1b0ee95d69606c35d@linux-foundation.org> User-Agent: Mutt/1.5.17 (2007-11-01) X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 69A62801D3D7 X-Stat-Signature: sdxn7ed4t1pwwsp8wottifnuzrinmwj3 Authentication-Results: imf06.hostedemail.com; dkim=none; spf=none (imf06.hostedemail.com: domain of hch@lst.de has no SPF policy when checking 213.95.11.211) smtp.mailfrom=hch@lst.de; dmarc=none X-HE-Tag: 1626240524-834191 Content-Transfer-Encoding: quoted-printable 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 Tue, Jul 13, 2021 at 06:31:23PM -0700, Andrew Morton wrote: > On Tue, 13 Jul 2021 07:52:30 +0200 Christoph Hellwig wrote= : >=20 > > memcpy_to_page and memzero_page can write to arbitrary pages, which c= ould > > be in the page cache or in high memory, so call flush_kernel_dcache_= pages > > to flush the dcache. >=20 > I assume this presently is not known to cause any problems, but that > some problems might be discovered in the future? In which case, > should we cc:stable? This is a problem when using these helpers on dcache challeneged architectures. Right now there are just a few users, chances are no one used the PC floppy dr=D1=96ver, the aha1542 driver for an ISA SCSI HBA, and a few advanced and optional btrfs and ext4 features on those platforms yet since the conversion. So yes, stable would be good.