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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 0851EC433E6 for ; Tue, 2 Feb 2021 13:32:20 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (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 706FC64DDA for ; Tue, 2 Feb 2021 13:32:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 706FC64DDA 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-nvdimm-bounces@lists.01.org Received: from ml01.vlan13.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 1A572100EA2A6; Tue, 2 Feb 2021 05:32:19 -0800 (PST) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=195.135.220.15; helo=mx2.suse.de; envelope-from=mhocko@suse.com; receiver= Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 5CA36100EAB6B for ; Tue, 2 Feb 2021 05:32:16 -0800 (PST) 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> Message-ID-Hash: EXTQR6HNVVOSQCTU6LUSD6UKHWUOYW3X X-Message-ID-Hash: EXTQR6HNVVOSQCTU6LUSD6UKHWUOYW3X X-MailFrom: mhocko@suse.com X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation CC: Mike Rapoport , James Bottomley , Andrew Morton , Alexander Viro , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christopher Lameter , Dave Hansen , Elena Reshetova , "H. Peter Anvin" , Ingo Molnar , "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 Ander sen , 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, Hagen Paul Pfeifer , Palmer Dabbelt X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org