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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 B27C4C2BBD5 for ; Fri, 18 Dec 2020 09:44:46 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 53D0223A63 for ; Fri, 18 Dec 2020 09:44:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 53D0223A63 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9D1F66B005C; Fri, 18 Dec 2020 04:44:45 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 95AFE6B005D; Fri, 18 Dec 2020 04:44:45 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 84A8D6B0068; Fri, 18 Dec 2020 04:44:45 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0076.hostedemail.com [216.40.44.76]) by kanga.kvack.org (Postfix) with ESMTP id 6F1F76B005C for ; Fri, 18 Dec 2020 04:44:45 -0500 (EST) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 4375C11019 for ; Fri, 18 Dec 2020 09:44:45 +0000 (UTC) X-FDA: 77605918530.28.room99_091379d2743c Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin28.hostedemail.com (Postfix) with ESMTP id 26522EFDA for ; Fri, 18 Dec 2020 09:44:45 +0000 (UTC) X-HE-Tag: room99_091379d2743c X-Filterd-Recvd-Size: 3473 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf21.hostedemail.com (Postfix) with ESMTP for ; Fri, 18 Dec 2020 09:44:44 +0000 (UTC) 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=1608284683; 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=qvWpWbEVzaGdCtT7lY02iDD8k+ikMF0dcZg/sL419MU=; b=XxjUmRtsLsgb930BhBZuWO8HArjYr53zHDvbqLhbU11F5AoFpegckrbl6Lp7seCfOsPrxo vJa7+rmjsW39l5Lim+zoAJPPG48d514n+n6dyL+fLEXm9WidgFnEUXaykQBsb8T9nHljwD dhrssBMDGOgEH5Nqhncc1j///AKYo/w= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 9A480AC7B; Fri, 18 Dec 2020 09:44:43 +0000 (UTC) Date: Fri, 18 Dec 2020 10:44:42 +0100 From: Michal Hocko To: Pavel Tatashin Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, vbabka@suse.cz, 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 Subject: Re: [PATCH v4 06/10] memory-hotplug.rst: add a note about ZONE_MOVABLE and page pinning Message-ID: <20201218094442.GU32193@dhcp22.suse.cz> References: <20201217185243.3288048-1-pasha.tatashin@soleen.com> <20201217185243.3288048-7-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201217185243.3288048-7-pasha.tatashin@soleen.com> 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: On Thu 17-12-20 13:52:39, Pavel Tatashin wrote: > 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 5c4432c96c4b..c6618f99f765 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 > -- > 2.25.1 > -- Michal Hocko SUSE Labs