Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761713Ab3DBJpc (ORCPT ); Tue, 2 Apr 2013 05:45:32 -0400 Received: from cantor2.suse.de ([195.135.220.15]:57870 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761070Ab3DBJp1 (ORCPT ); Tue, 2 Apr 2013 05:45:27 -0400 Date: Tue, 2 Apr 2013 11:45:24 +0200 From: Michal Hocko To: "Aneesh Kumar K.V" Cc: Naoya Horiguchi , 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: <20130402094524.GF24345@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> <874nfqesut.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <874nfqesut.fsf@linux.vnet.ibm.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: 1978 Lines: 48 On Mon 01-04-13 10:43:14, Aneesh Kumar K.V wrote: > Michal Hocko writes: > > > 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. > > > > But we still need to hold hugetlb_lock around that right ? Right. Racing hugetlb_cgroup_move_parent and hugetlb_cgroup_migrate could lead to newpage pointing to NULL cgroup. That could be fixed by checking old page cgroup for NULL inside hugetlb_lock and using list_for_each_safe in hugetlb_cgroup_css_offline no? -- 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/