Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756809Ab3C1Ixa (ORCPT ); Thu, 28 Mar 2013 04:53:30 -0400 Received: from cantor2.suse.de ([195.135.220.15]:59921 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756057Ab3C1IxZ (ORCPT ); Thu, 28 Mar 2013 04:53:25 -0400 Date: Thu, 28 Mar 2013 09:53:20 +0100 From: Michal Hocko To: Naoya Horiguchi Cc: "Aneesh Kumar K.V" , linux-mm@kvack.org, Andrew Morton , Mel Gorman , Hugh Dickins , KOSAKI Motohiro , Andi Kleen , Hillf Danton , linux-kernel@vger.kernel.org Subject: Re: [PATCH 03/10] soft-offline: use migrate_pages() instead of migrate_huge_page() Message-ID: <20130328085320.GC3018@dhcp22.suse.cz> References: <1363983835-20184-1-git-send-email-n-horiguchi@ah.jp.nec.com> <1363983835-20184-4-git-send-email-n-horiguchi@ah.jp.nec.com> <87boa69z6j.fsf@linux.vnet.ibm.com> <20130327135250.GI16579@dhcp22.suse.cz> <1364411964-iukb7m94-mutt-n-horiguchi@ah.jp.nec.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1364411964-iukb7m94-mutt-n-horiguchi@ah.jp.nec.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2410 Lines: 55 On Wed 27-03-13 15:19:24, Naoya Horiguchi wrote: > On Wed, Mar 27, 2013 at 02:52:50PM +0100, Michal Hocko wrote: > > On Tue 26-03-13 16:59:40, Aneesh Kumar K.V wrote: > > > Naoya Horiguchi writes: > > [...] > > > > diff --git v3.9-rc3.orig/mm/memory-failure.c v3.9-rc3/mm/memory-failure.c > > > > index df0694c..4e01082 100644 > > > > --- v3.9-rc3.orig/mm/memory-failure.c > > > > +++ v3.9-rc3/mm/memory-failure.c > > > > @@ -1467,6 +1467,7 @@ static int soft_offline_huge_page(struct page *page, int flags) > > > > int ret; > > > > unsigned long pfn = page_to_pfn(page); > > > > struct page *hpage = compound_head(page); > > > > + LIST_HEAD(pagelist); > > > > > > > > /* > > > > * This double-check of PageHWPoison is to avoid the race with > > > > @@ -1482,12 +1483,20 @@ static int soft_offline_huge_page(struct page *page, int flags) > > > > unlock_page(hpage); > > > > > > > > /* Keep page count to indicate a given hugepage is isolated. */ > > > > - ret = migrate_huge_page(hpage, new_page, MPOL_MF_MOVE_ALL, > > > > - MIGRATE_SYNC); > > > > - put_page(hpage); > > > > + list_move(&hpage->lru, &pagelist); > > > > > > we use hpage->lru to add the hpage to h->hugepage_activelist. This will > > > break a hugetlb cgroup removal isn't it ? > > > > This particular part will not break removal because > > hugetlb_cgroup_css_offline loops until hugetlb_cgroup_have_usage is 0. > > Right. > > > Little bit offtopic: > > Btw. hugetlb migration breaks to charging even before this patchset > > AFAICS. The above put_page should remove the last reference and then it > > will uncharge it but I do not see anything that would charge a new page. > > This is all because regula LRU pages are uncharged when they are > > unmapped. But this a different story not related to this series. > > It seems to me that alloc_huge_page_node() needs to call > hugetlb_cgroup_charge_cgroup() before dequeuing a new hugepage. This is not that easy because the new page has to be charged to the same group as the original one but the migration process might be running in the context of a different group. -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/