From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758372Ab2C1Ri7 (ORCPT ); Wed, 28 Mar 2012 13:38:59 -0400 Received: from e23smtp02.au.ibm.com ([202.81.31.144]:49608 "EHLO e23smtp02.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753377Ab2C1Ri5 (ORCPT ); Wed, 28 Mar 2012 13:38:57 -0400 From: "Aneesh Kumar K.V" To: Michal Hocko Cc: linux-mm@kvack.org, mgorman@suse.de, kamezawa.hiroyu@jp.fujitsu.com, dhillf@gmail.com, aarcange@redhat.com, akpm@linux-foundation.org, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org Subject: Re: [PATCH -V4 08/10] hugetlbfs: Add a list for tracking in-use HugeTLB pages In-Reply-To: <20120328135845.GH20949@tiehlicka.suse.cz> References: <1331919570-2264-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1331919570-2264-9-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <20120328135845.GH20949@tiehlicka.suse.cz>User-Agent: Notmuch/0.11.1+346~g13d19c3 (http://notmuchmail.org) Emacs/23.3.1 (x86_64-pc-linux-gnu) Date: Wed, 28 Mar 2012 23:08:34 +0530 Message-ID: <87vclo1v8l.fsf@skywalker.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii x-cbid: 12032807-5490-0000-0000-00000108B888 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Michal Hocko writes: > On Fri 16-03-12 23:09:28, Aneesh Kumar K.V wrote: >> From: "Aneesh Kumar K.V" >> >> hugepage_activelist will be used to track currently used HugeTLB pages. >> We need to find the in-use HugeTLB pages to support memcg removal. >> On memcg removal we update the page's memory cgroup to point to >> parent cgroup. >> >> Signed-off-by: Aneesh Kumar K.V >> --- >> include/linux/hugetlb.h | 1 + >> mm/hugetlb.c | 23 ++++++++++++++++++----- >> 2 files changed, 19 insertions(+), 5 deletions(-) >> >> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h >> index cbd8dc5..6919100 100644 >> --- a/include/linux/hugetlb.h >> +++ b/include/linux/hugetlb.h > [...] >> @@ -2319,14 +2322,24 @@ void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, >> page = pte_page(pte); >> if (pte_dirty(pte)) >> set_page_dirty(page); >> - list_add(&page->lru, &page_list); >> + >> + spin_lock(&hugetlb_lock); >> + list_move(&page->lru, &page_list); >> + spin_unlock(&hugetlb_lock); > > Why do we really need the spinlock here? It does a list_del from hugepage_activelist. > >> } >> spin_unlock(&mm->page_table_lock); >> flush_tlb_range(vma, start, end); >> mmu_notifier_invalidate_range_end(mm, start, end); >> list_for_each_entry_safe(page, tmp, &page_list, lru) { >> page_remove_rmap(page); >> - list_del(&page->lru); >> + /* >> + * We need to move it back huge page active list. If we are >> + * holding the last reference, below put_page will move it >> + * back to free list. >> + */ >> + spin_lock(&hugetlb_lock); >> + list_move(&page->lru, &h->hugepage_activelist); >> + spin_unlock(&hugetlb_lock); > > This spinlock usage doesn't look nice but I guess we do not have many > other options. > -aneesh