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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 B607FC433DB for ; Tue, 2 Feb 2021 13:33:29 +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 70BCD64F45 for ; Tue, 2 Feb 2021 13:33:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 70BCD64F45 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.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-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=71CsnAiitGfyMW7LA3QQKX1qlhA6jLyWZoKg90eiG7k=; b=derYzpjjgJlF7jKik+YSF/quy WkRx9cV5cPcaI7LmEVtZNhS8rnES/eeGqQ7HyG06Vmb86vH/ddtpt1sdlWZGo5N7+ix6VumkWOfKm sQ79Dh10xZ58yRUjX6uGd+gGKAcyW1T5LaMQIRiivGkhFMZGrXILZWmm/z4J8Thp3NZnUTT1DDqMi KuDUU4cld7Endbg0FkrcgR6rQpfEnzUtAfX/wINLYZfZTGN19rueO/k3e1zZN6QkmnKTb44XIabwl TxFuPrtzL8d+r6I33FMmoUBW1OPitc91nKB/wew86P70XB7coTl1dKnsfjrttxbZ9pshtxatzevSf Nbdwj1cCw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l6vn1-0001IY-FM; Tue, 02 Feb 2021 13:32:19 +0000 Received: from mx2.suse.de ([195.135.220.15]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l6vmx-0001GM-UP; Tue, 02 Feb 2021 13:32:17 +0000 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=1612272735; 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=qhASYy52HrQdJQILCHxBxIDs1mcnSSfDvbUg8Hv9Huk=; b=O35yhETCIJcmvITBzmA06eT7x4pieJO9swql+e/dEuWJvoBkcPrcGAQe2sM2r3gNYCJ97G cutl0j+I7mXW23xuyyuYKFCdVv7+WC+a62VtrpsBAxAPUoJKjRiqBrbLEGz3xn0w2G09n8 8FyL2zHquLohp9unYR6VoEzGZD+347Q= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id B66D6AF92; Tue, 2 Feb 2021 13:32:14 +0000 (UTC) Date: Tue, 2 Feb 2021 14:32:13 +0100 From: Michal Hocko To: David Hildenbrand Subject: Re: [PATCH v16 07/11] secretmem: use PMD-size pages to amortize direct map fragmentation Message-ID: 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> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <6653288a-dd02-f9de-ef6a-e8d567d71d53@redhat.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210202_083216_242520_2011C87B X-CRM114-Status: GOOD ( 16.26 ) 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-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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). 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. If secretmem behaves along those existing models then we know what to expect at least. -- Michal Hocko SUSE Labs _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel