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[141.146.126.79]) by mx.google.com with ESMTPS id m4si1176644qvi.70.2019.02.27.14.01.05 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 27 Feb 2019 14:01:05 -0800 (PST) Received-SPF: pass (google.com: domain of mike.kravetz@oracle.com designates 141.146.126.79 as permitted sender) client-ip=141.146.126.79; Authentication-Results: mx.google.com; dkim=pass header.i=@oracle.com header.s=corp-2018-07-02 header.b=gaY26Ndi; spf=pass (google.com: domain of mike.kravetz@oracle.com designates 141.146.126.79 as permitted sender) smtp.mailfrom=mike.kravetz@oracle.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=oracle.com Received: from pps.filterd (aserp2130.oracle.com [127.0.0.1]) by aserp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x1RLs1xM123838; Wed, 27 Feb 2019 22:01:04 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=LQ5rYxmcH3WAzFf0sRvQ3XlMmD9QOhCgoOKYt96kr/E=; b=gaY26NdiNElYQFqrnLKZRR0hM5RzzHN3XsCcgmOqE1GfdTdHthzQGn0kiwbqJBA/NPNZ pGBiumlOS0qcNZGTSA0B+lbkZ7KQYBRFR6EZhldlbBGVxcIbh7hS1onSFTty9IoAMVB2 2Hb63htXFBAwEv4iVdXcmS3E41uYMtdciZZGiOAye8/IlT87DGqgHplrHUdvHed2j0O6 XykeNh/y93s/uW8LMJgmSyNHoyCg+udUPpdVXX/tRxybkIl/7JfmGGARicvrJkKVpoyY LnubGmu58CiDnP1qWFTd+6EadHfOhKba9fq/64qGjClCPzk6d1AgeF8GfYbXX/F8jYns fw== Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by aserp2130.oracle.com with ESMTP id 2qtupeds84-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 27 Feb 2019 22:01:04 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id x1RM0wGE002947 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 27 Feb 2019 22:00:59 GMT Received: from abhmp0005.oracle.com (abhmp0005.oracle.com [141.146.116.11]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x1RM0w58026884; Wed, 27 Feb 2019 22:00:58 GMT Received: from [192.168.1.164] (/50.38.38.67) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 27 Feb 2019 14:00:58 -0800 Subject: Re: [RFC PATCH] mm,memory_hotplug: Unlock 1GB-hugetlb on x86_64 To: Oscar Salvador , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, mhocko@suse.com, david@redhat.com References: <20190221094212.16906-1-osalvador@suse.de> <20190227215109.cpiaheyqs2qdbl7p@d104.suse.de> From: Mike Kravetz Message-ID: <201cc8d8-953f-f198-bbfe-96470136db68@oracle.com> Date: Wed, 27 Feb 2019 14:00:57 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190227215109.cpiaheyqs2qdbl7p@d104.suse.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9180 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1902270143 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 2/27/19 1:51 PM, Oscar Salvador wrote: > On Thu, Feb 21, 2019 at 10:42:12AM +0100, Oscar Salvador wrote: >> [1] https://lore.kernel.org/patchwork/patch/998796/ >> >> Signed-off-by: Oscar Salvador > > Any further comments on this? > I do have a "concern" I would like to sort out before dropping the RFC: > > It is the fact that unless we have spare gigantic pages in other notes, the > offlining operation will loop forever (until the customer cancels the operation). > While I do not really like that, I do think that memory offlining should be done > with some sanity, and the administrator should know in advance if the system is going > to be able to keep up with the memory pressure, aka: make sure we got what we need in > order to make the offlining operation to succeed. > That translates to be sure that we have spare gigantic pages and other nodes > can take them. > > Given said that, another thing I thought about is that we could check if we have > spare gigantic pages at has_unmovable_pages() time. > Something like checking "h->free_huge_pages - h->resv_huge_pages > 0", and if it > turns out that we do not have gigantic pages anywhere, just return as we have > non-movable pages. Of course, that check would be racy. Even if there is an available gigantic page at has_unmovable_pages() time there is no guarantee it will be there when we want to allocate/use it. But, you would at least catch 'most' cases of looping forever. > But I would rather not convulate has_unmovable_pages() with such checks and "trust" > the administrator. Agree -- Mike Kravetz