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 429E5C433DB for ; Wed, 20 Jan 2021 13:48:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F3C3D23357 for ; Wed, 20 Jan 2021 13:48:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387953AbhATNbL (ORCPT ); Wed, 20 Jan 2021 08:31:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38626 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731723AbhATNXG (ORCPT ); Wed, 20 Jan 2021 08:23:06 -0500 Received: from mail-qk1-x732.google.com (mail-qk1-x732.google.com [IPv6:2607:f8b0:4864:20::732]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E0FD9C061757 for ; Wed, 20 Jan 2021 05:22:25 -0800 (PST) Received: by mail-qk1-x732.google.com with SMTP id 22so25234028qkf.9 for ; Wed, 20 Jan 2021 05:22:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=TxOJ2i1obQZTYWUjOO4AH/QKsmg0DUJ9EGaechEIo20=; b=IvzX1RMAtfsiwGFzzn5FfORQgcXPhllACg7D+ANj7TlWPd5qMsoyPmKGn1XhVA8NwM tafb4+W9ckHIwIC2JBfwYCAPgXVbUIzt+6pL2UDYN50uqUst7fkRN9pWNY9xSsstQzUA bb1vo+9Prb3OaiUP7mgZO7sGWE3g0yX548ApY/8loBpncFwLJA4OaUHs+Xei5i/ul45A Poyg8uDGFCtY7vtgdHVF74Rvl9Rq59pDg4A1B9F/2weKRBdIUNb8ORuYNQnaTBdjr5Y+ abTearQ0KBLILW07vILaeT4ncQ5ARwtQ3rEQoueKnAru9qTf91hl1CGFQlLXQ2yJXPYo ZxbA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=TxOJ2i1obQZTYWUjOO4AH/QKsmg0DUJ9EGaechEIo20=; b=udU9nnzhUoR2Lz0Cmy4SnZJvpUigFMp/iYNb+qKKYBnP7fLDU8qor5Z042ld0qdU42 iRFR3z2wvL0u7BqczM6PcgcJraoa8RJNNLoxU79/ioj7kfF4UeW+B24ysg0K7iwGRn9N 2Dd5gN47vygov5XFZdD/E8HqQ6evixnMKcYMdAdPySAldPOV8nCK/oEt1gVptHUa4EHc jsFOh7gQejhfGMpo3ZsLu/cddIou24ZQODm8uBtZammbF4ljUDdcg3fiQmwE6m8wSuNU XNmZWhVZ1d8Sebdn/wQHey9ypyXuhV6+CFhMwWcRtmegRxZSlFICgGIQBBz93lnxFCEw Jv2Q== X-Gm-Message-State: AOAM530JiumUL6vI7ak3MWQHNQpGOjL6d7maoHGmRQ+bqwX0+sMUk2/4 XASfXKjy2Cy6xQ1lHJjth0I6IQ== X-Google-Smtp-Source: ABdhPJxVh5jUl4y5I89LvXDP0n+KjibmY3MDSvd+QOMJtVbYZtAlkbEyk4UcJVKl2qWGnRtxmq5muA== X-Received: by 2002:a05:620a:125c:: with SMTP id a28mr9451371qkl.112.1611148945095; Wed, 20 Jan 2021 05:22:25 -0800 (PST) Received: from ziepe.ca ([206.223.160.26]) by smtp.gmail.com with ESMTPSA id r190sm1313094qka.54.2021.01.20.05.22.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Jan 2021 05:22:24 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1l2DRH-004Tyo-Ee; Wed, 20 Jan 2021 09:22:23 -0400 Date: Wed, 20 Jan 2021 09:22:23 -0400 From: Jason Gunthorpe To: Pavel Tatashin Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, vbabka@suse.cz, mhocko@suse.com, david@redhat.com, osalvador@suse.de, dan.j.williams@intel.com, sashal@kernel.org, tyhicks@linux.microsoft.com, iamjoonsoo.kim@lge.com, mike.kravetz@oracle.com, rostedt@goodmis.org, mingo@redhat.com, peterz@infradead.org, mgorman@suse.de, willy@infradead.org, rientjes@google.com, jhubbard@nvidia.com, linux-doc@vger.kernel.org, ira.weiny@intel.com, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v6 10/14] memory-hotplug.rst: add a note about ZONE_MOVABLE and page pinning Message-ID: <20210120132223.GH4605@ziepe.ca> References: <20210120014333.222547-1-pasha.tatashin@soleen.com> <20210120014333.222547-11-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210120014333.222547-11-pasha.tatashin@soleen.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 19, 2021 at 08:43:29PM -0500, Pavel Tatashin wrote: > +.. note:: > + Techniques that rely on long-term pinnings of memory (especially, RDMA and > + vfio) are fundamentally problematic with ZONE_MOVABLE and, therefore, memory > + hot remove. Pinned pages cannot reside on ZONE_MOVABLE, to guarantee that > + memory can still get hot removed - be aware that pinning can fail even if > + there is plenty of free memory in ZONE_MOVABLE. In addition, using > + ZONE_MOVABLE might make page pinning more expensive, because pages have to be > + migrated off that zone first. Just to point out, if anyone is using RDMA/etc with hotplug memory, this series is likekly going to be a major regression for those users. Jason