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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 D8E2EC433E0 for ; Tue, 9 Feb 2021 20:08:36 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 35F5D64E9C for ; Tue, 9 Feb 2021 20:08:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 35F5D64E9C Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A44F66B0005; Tue, 9 Feb 2021 15:08:35 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9CDDA6B006C; Tue, 9 Feb 2021 15:08:35 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 86DA66B006E; Tue, 9 Feb 2021 15:08:35 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0198.hostedemail.com [216.40.44.198]) by kanga.kvack.org (Postfix) with ESMTP id 6EC5B6B0005 for ; Tue, 9 Feb 2021 15:08:35 -0500 (EST) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 37955185798BE for ; Tue, 9 Feb 2021 20:08:35 +0000 (UTC) X-FDA: 77799816990.15.plant56_1414d182760a Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin15.hostedemail.com (Postfix) with ESMTP id 14118185B9EC5 for ; Tue, 9 Feb 2021 20:08:35 +0000 (UTC) X-HE-Tag: plant56_1414d182760a X-Filterd-Recvd-Size: 5075 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf17.hostedemail.com (Postfix) with ESMTP for ; Tue, 9 Feb 2021 20:08:34 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1612901312; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=utBmzEHnMldk+xybu3FUHQ/4GijdaViYwt5S9/fMX5g=; b=TjFv3w1m/0Glle7o/mpLcPWsTy958OLjFP0MF4y2grgkrogeIq5dCnnfB5BszcW5ggUnqY LL4MV1a1lL2B5WOEu6FaOYZ3DET/TzX9b1n3q4/VP0Y/08QiHTyolRop/Pd6AqhLXBScSy PBnAIDa+ir2IADhVPtKtqxwjkXo403U= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id AC40AADF0; Tue, 9 Feb 2021 20:08:32 +0000 (UTC) Date: Tue, 9 Feb 2021 21:08:31 +0100 From: Michal Hocko To: David Hildenbrand Cc: Mike Rapoport , Andrew Morton , Alexander Viro , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christopher Lameter , Dan Williams , Dave Hansen , Elena Reshetova , "H. Peter Anvin" , Ingo Molnar , James Bottomley , "Kirill A. Shutemov" , Matthew Wilcox , Mark Rutland , Mike Rapoport , Michael Kerrisk , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , Rick Edgecombe , Roman Gushchin , Shakeel Butt , Shuah Khan , Thomas Gleixner , Tycho Andersen , Will Deacon , linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org, x86@kernel.org Subject: Re: [PATCH v17 00/10] mm: introduce memfd_secret system call to create "secret" memory areas Message-ID: References: <20210208211326.GV242749@kernel.org> <1F6A73CF-158A-4261-AA6C-1F5C77F4F326@redhat.com> <662b5871-b461-0896-697f-5e903c23d7b9@redhat.com> <8cbfe2c3-cfc6-72e0-bab1-852f80e20684@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8cbfe2c3-cfc6-72e0-bab1-852f80e20684@redhat.com> 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 09-02-21 17:17:22, David Hildenbrand wrote: > On 09.02.21 14:25, Michal Hocko wrote: > > On Tue 09-02-21 11:23:35, David Hildenbrand wrote: > > [...] > > > I am constantly trying to fight for making more stuff MOVABLE instead of > > > going into the other direction (e.g., because it's easier to implement, > > > which feels like the wrong direction). > > > > > > Maybe I am the only person that really cares about ZONE_MOVABLE these days > > > :) I can't stop such new stuff from popping up, so at least I want it to be > > > documented. > > > > MOVABLE zone is certainly an important thing to keep working. And there > > is still quite a lot of work on the way. But as I've said this is more > > of a outlier than a norm. On the other hand movable zone is kinda hard > > requirement for a lot of application and it is to be expected that > > many features will be less than 100% compatible. Some usecases even > > impossible. That's why I am arguing that we should have a central > > document where the movable zone is documented with all the potential > > problems we have encountered over time and explicitly state which > > features are fully/partially incompatible. > > > > I'll send a mail during the next weeks to gather current restrictions to > document them (and include my brain dump). We might see more excessive use > of ZONE_MOVABLE in the future and as history told us, of CMA as well. We > really should start documenting/caring. Excellent! Thanks a lot. I will do my best to help reviewing that. > @Mike, it would be sufficient for me if one of your patches at least mention > the situation in the description like > > "Please note that secretmem currently behaves much more like long-term GUP > instead of mlocked memory; secretmem is unmovable memory directly > consumed/controlled by user space. secretmem cannot be placed onto > ZONE_MOVABLE/CMA. Sounds good to me. -- Michal Hocko SUSE Labs