From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx134.postini.com [74.125.245.134]) by kanga.kvack.org (Postfix) with SMTP id ECB456B0005 for ; Wed, 20 Mar 2013 19:55:34 -0400 (EDT) Received: by mail-da0-f46.google.com with SMTP id y19so1269330dan.5 for ; Wed, 20 Mar 2013 16:55:34 -0700 (PDT) Message-ID: <514A4C70.2020303@gmail.com> Date: Thu, 21 Mar 2013 07:55:28 +0800 From: Simon Jeons MIME-Version: 1.0 Subject: Re: [PATCH 8/9] memory-hotplug: enable memory hotplug to handle hugepage References: <1361475708-25991-1-git-send-email-n-horiguchi@ah.jp.nec.com> <1361475708-25991-9-git-send-email-n-horiguchi@ah.jp.nec.com> <51490AD8.9050308@gmail.com> <1363817148-rlt5mp5n-mutt-n-horiguchi@ah.jp.nec.com> In-Reply-To: <1363817148-rlt5mp5n-mutt-n-horiguchi@ah.jp.nec.com> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Naoya Horiguchi Cc: linux-mm@kvack.org, Andrew Morton , Mel Gorman , Hugh Dickins , KOSAKI Motohiro , Andi Kleen , linux-kernel@vger.kernel.org Hi Naoya, On 03/21/2013 06:05 AM, Naoya Horiguchi wrote: > On Wed, Mar 20, 2013 at 09:03:20AM +0800, Simon Jeons wrote: >> Hi Naoya, >> On 02/22/2013 03:41 AM, Naoya Horiguchi wrote: >>> Currently we can't offline memory blocks which contain hugepages because >>> a hugepage is considered as an unmovable page. But now with this patch >>> series, a hugepage has become movable, so by using hugepage migration we >>> can offline such memory blocks. >>> >>> What's different from other users of hugepage migration is that we need >>> to decompose all the hugepages inside the target memory block into free >> For other hugepage migration users, hugepage should be freed to >> hugepage_freelists after migration, but why I don't see any codes do >> this? > The source hugepages which are migrated by NUMA related system calls > (migrate_pages(2), move_pages(2), and mbind(2)) are still useable, > so we simply free them into free hugepage pool. It seems that you misunderstand why I confuse. I can't find where free huge pages to hugepage pool, could you point out to me? > OTOH, the source hugepages migrated by memory hotremove should not be > reusable, because users of memory hotremove want to remove the memory > from the system. So we need to free such hugepages forcibly into the > buddy pages, otherwise memory offining doesn't work. > > Thanks, > Naoya -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org