From patchwork Thu Feb 11 16:24:23 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pasha Tatashin X-Patchwork-Id: 12083673 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=-16.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 F2405C433E0 for ; Thu, 11 Feb 2021 16:24:55 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id AA8F664E92 for ; Thu, 11 Feb 2021 16:24:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AA8F664E92 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=soleen.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id CCB746B0118; Thu, 11 Feb 2021 11:24:46 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C2B686B0119; Thu, 11 Feb 2021 11:24:46 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ACCAE6B011A; Thu, 11 Feb 2021 11:24:46 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0234.hostedemail.com [216.40.44.234]) by kanga.kvack.org (Postfix) with ESMTP id 91C226B0118 for ; Thu, 11 Feb 2021 11:24:46 -0500 (EST) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 4C562180AD81A for ; Thu, 11 Feb 2021 16:24:46 +0000 (UTC) X-FDA: 77806510572.02.69DBAFA Received: from mail-qt1-f171.google.com (mail-qt1-f171.google.com [209.85.160.171]) by imf24.hostedemail.com (Postfix) with ESMTP id 177A6A0009DA for ; Thu, 11 Feb 2021 16:24:44 +0000 (UTC) Received: by mail-qt1-f171.google.com with SMTP id n28so4528167qtv.12 for ; Thu, 11 Feb 2021 08:24:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=soleen.com; s=google; h=from:to:subject:date:message-id:in-reply-to:references:mime-version :content-transfer-encoding; bh=1y8YVJPfrTUIiLzCoLZfzLsb38Z+1ZQwX7g2yPLqtWE=; b=BMZBD7oFx42XW1Uk/eIT+ek2yqmO2Unwl542eAk9EtAij5sF54ALjQ+UxIzV6fseqn 9KHoTP/AkRo/I9nUl/bckx72sPe9TsPWqhTnETapUUtoMI91yr0quP6I2g4jL9ElIwQI qlZT7xirvXSEQOXrLZ8Glpk4Dt2Y6sD2Vo7KfitLgkUuUXK0jU1Rhp+kNsDhVjc8oyTr UatAl1MdhuE/8fWIVU9acVXddvE7Yvu1P1HbnVuDAEZ3oRvBX5RSCzPGZplfL9STagRw YC3vR6mguTAhApUEkxNsXoKWoXBOMgXWuvtlZNOD+cHwfHFMlDheS5Kyw2acUXRC6opX Y2aA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=1y8YVJPfrTUIiLzCoLZfzLsb38Z+1ZQwX7g2yPLqtWE=; b=JaHq8Hm8xcow1n+NRMjw27XbgCwQxoYwp5ev/1dP7lIoqodOlmJV7rVCIri22paRBD eIYoqBtsHYeoiEMW0qPjEnIHwp0oyMGKcUls0PzFkXKREl35mk2jF6eoy6V6MgGI6YR8 2g9HB3d2Cf/Bv2aIDTMeUB0wTwVXG2kaShc7neySQSDE7JwgwM/QF/0obz5cFtm2DGZy UruVIT7K3mzl9xXtppwi7usnOT/vnbdrxJ5jnHU6SwYNApxnkUS9PQJXbd0sZiBdREFB l9z9BdryHqH6/yBzGj68V6m1W68ggUo2Hcvx+p7VOhzxmFdmeBfzyXTZGG6SWRqmyQ3k y/Ew== X-Gm-Message-State: AOAM533BKl6xkTsjbo8JEWf7/+jLjrykNfhd7CS+z+UHrSWL+L3wO85c GMthjVHO1xQlUyMXaOKRs96D5g== X-Google-Smtp-Source: ABdhPJywW3R49OtwqHgSlgYoPuSklhjeeJfwnn3touZTrtXT9dvY7n8wJc0mz/T1j2uyZvz6BoDYwg== X-Received: by 2002:ac8:4d43:: with SMTP id x3mr8211573qtv.17.1613060685225; Thu, 11 Feb 2021 08:24:45 -0800 (PST) Received: from localhost.localdomain (c-73-69-118-222.hsd1.nh.comcast.net. [73.69.118.222]) by smtp.gmail.com with ESMTPSA id i23sm3831778qtq.42.2021.02.11.08.24.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Feb 2021 08:24:44 -0800 (PST) From: Pavel Tatashin To: pasha.tatashin@soleen.com, 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, jgg@ziepe.ca, 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, jmorris@namei.org Subject: [PATCH v10 10/14] memory-hotplug.rst: add a note about ZONE_MOVABLE and page pinning Date: Thu, 11 Feb 2021 11:24:23 -0500 Message-Id: <20210211162427.618913-11-pasha.tatashin@soleen.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210211162427.618913-1-pasha.tatashin@soleen.com> References: <20210211162427.618913-1-pasha.tatashin@soleen.com> MIME-Version: 1.0 X-Stat-Signature: rtojac8niuxbgkyswnczdquj4utag6px X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 177A6A0009DA Received-SPF: none (soleen.com>: No applicable sender policy available) receiver=imf24; identity=mailfrom; envelope-from=""; helo=mail-qt1-f171.google.com; client-ip=209.85.160.171 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1613060684-329491 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: Document the special handling of page pinning when ZONE_MOVABLE present. Signed-off-by: Pavel Tatashin Suggested-by: David Hildenbrand Acked-by: Michal Hocko --- Documentation/admin-guide/mm/memory-hotplug.rst | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/Documentation/admin-guide/mm/memory-hotplug.rst b/Documentation/admin-guide/mm/memory-hotplug.rst index 5307f90738aa..05d51d2d8beb 100644 --- a/Documentation/admin-guide/mm/memory-hotplug.rst +++ b/Documentation/admin-guide/mm/memory-hotplug.rst @@ -357,6 +357,15 @@ creates ZONE_MOVABLE as following. Unfortunately, there is no information to show which memory block belongs to ZONE_MOVABLE. This is TBD. +.. 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. + .. _memory_hotplug_how_to_offline_memory: How to offline memory