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,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,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 2126FC43381 for ; Tue, 2 Feb 2021 14:14:08 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D200064E2B for ; Tue, 2 Feb 2021 14:14:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D200064E2B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:Subject: From:References:To:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=xDkx1aXccLNNSL505nugsGqmjOALumlwJiTsgzyc5MI=; b=EYlMboD9vnpoGCbB+FGYKYAtA zhzMFsWEwCjqm6u+kJgfpDMKo2l5w7nwYoczbSG7IOSEsiJqrvhNnUMitzgDnoOKKBNJ7qmhpZ409 /ucs2rAnM4u/musx46ZRL43FqMDnlauW2wn30BWYaPg307EWvJL6aZfVAcQJdKVUXzYitT7lUVr+L BtrLMYk5/OerD/wuPlyyxJP1VgXC+dEVnqsyL2hn4e08VO/7GS5qQlrbJP7ffxtGsCXOHZ3bhwFto Z6lzv7r1VwhH867HYLENhKind3dFPl25I3siGXIbXDhfmLBSAvjJBj/Wu3Gba6jyB23IDP9hQXpNk rJXqrstxA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l6wQD-0006eE-Ev; Tue, 02 Feb 2021 14:12:49 +0000 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l6wQ4-0006aD-Ig for linux-arm-kernel@lists.infradead.org; Tue, 02 Feb 2021 14:12:43 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612275160; 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=mAXEVjxGkaVgIUFhfXA1HRN3FgtOlJcIpAQw2h/beVM=; b=eKDUxb1+pqSJGwixp0bJb9IpFbLQ2YWSNtr9y6B5b9tHnfKB8XWwqMi4lg2wcz689fqN+7 ixbEtjubRl8BQ3SthB9ROO4tXppvD18dReUGmXO7MA7mXPXT1SkBZZqlAPN5rjZaPaek3k ft4gaH36hp6hgsL1Zdqrv2sUA+94Msc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-460-DO7GaD-qPMSuJ9daYkp31A-1; Tue, 02 Feb 2021 09:12:35 -0500 X-MC-Unique: DO7GaD-qPMSuJ9daYkp31A-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B117B100A8E8; Tue, 2 Feb 2021 14:12:30 +0000 (UTC) Received: from [10.36.114.148] (ovpn-114-148.ams2.redhat.com [10.36.114.148]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6CE915B4A7; Tue, 2 Feb 2021 14:12:22 +0000 (UTC) To: Michal Hocko References: <303f348d-e494-e386-d1f5-14505b5da254@redhat.com> <20210126120823.GM827@dhcp22.suse.cz> <20210128092259.GB242749@kernel.org> <73738cda43236b5ac2714e228af362b67a712f5d.camel@linux.ibm.com> <6de6b9f9c2d28eecc494e7db6ffbedc262317e11.camel@linux.ibm.com> <20210202124857.GN242749@kernel.org> <6653288a-dd02-f9de-ef6a-e8d567d71d53@redhat.com> From: David Hildenbrand Organization: Red Hat GmbH Subject: Re: [PATCH v16 07/11] secretmem: use PMD-size pages to amortize direct map fragmentation Message-ID: <211f0214-1868-a5be-9428-7acfc3b73993@redhat.com> Date: Tue, 2 Feb 2021 15:12:21 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210202_091240_732595_5B8F98C6 X-CRM114-Status: GOOD ( 22.52 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Peter Zijlstra , Catalin Marinas , Dave Hansen , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, "H. Peter Anvin" , Christopher Lameter , Shuah Khan , Thomas Gleixner , Elena Reshetova , linux-arch@vger.kernel.org, Tycho Andersen , linux-nvdimm@lists.01.org, Will Deacon , x86@kernel.org, Matthew Wilcox , Mike Rapoport , Ingo Molnar , Michael Kerrisk , Palmer Dabbelt , Arnd Bergmann , James Bottomley , Hagen Paul Pfeifer , Borislav Petkov , Alexander Viro , Andy Lutomirski , Paul Walmsley , "Kirill A. Shutemov" , Dan Williams , linux-arm-kernel@lists.infradead.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Palmer Dabbelt , linux-fsdevel@vger.kernel.org, Shakeel Butt , Andrew Morton , Rick Edgecombe , Roman Gushchin , Mike Rapoport Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 02.02.21 14:32, Michal Hocko wrote: > On Tue 02-02-21 14:14:09, David Hildenbrand wrote: > [...] >> As already expressed, I dislike allowing user space to consume an unlimited >> number unmovable/unmigratable allocations. We already have that in some >> cases with huge pages (when the arch does not support migration) - but there >> we can at least manage the consumption using the whole max/reserved/free/... >> infrastructure. In addition, adding arch support for migration shouldn't be >> too complicated. > > Well, mlock is not too different here as well. Hugepages are arguably an > easier model because it requires an explicit pre-configuration by an > admin. Mlock doesn't have anything like that. Please also note that > while mlock pages are migrateable by default, this is not the case in > general because they can be configured to disalow migration to prevent > from minor page faults as some workloads require that (e.g. RT). Yeah, however that is a very special case. In most cases mlock() simply prevents swapping, you still have movable pages you can place anywhere you like (including on ZONE_MOVABLE). > Another example is ramdisk or even tmpfs (with swap storage depleted or > not configured). Both are PITA from the OOM POV but they are manageable > if people are careful. Right, but again, special cases - e.g., tmpfs explicitly has to be resized. > If secretmem behaves along those existing models > then we know what to expect at least. I think secretmem behaves much more like longterm GUP right now ("unmigratable", "lifetime controlled by user space", "cannot go on CMA/ZONE_MOVABLE"). I'd either want to reasonably well control/limit it or make it behave more like mlocked pages. -- Thanks, David / dhildenb _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel