From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx200.postini.com [74.125.245.200]) by kanga.kvack.org (Postfix) with SMTP id 53F386B00E2 for ; Mon, 11 Jun 2012 05:17:01 -0400 (EDT) Date: Mon, 11 Jun 2012 11:16:58 +0200 From: Michal Hocko Subject: Re: [PATCH -V8 10/16] hugetlb/cgroup: Add the cgroup pointer to page lru Message-ID: <20120611091658.GG12402@tiehlicka.suse.cz> References: <1339232401-14392-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1339232401-14392-11-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <20120611081653.GB12402@tiehlicka.suse.cz> <87oboq5ifb.fsf@skywalker.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87oboq5ifb.fsf@skywalker.in.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: "Aneesh Kumar K.V" Cc: linux-mm@kvack.org, kamezawa.hiroyu@jp.fujitsu.com, dhillf@gmail.com, rientjes@google.com, akpm@linux-foundation.org, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org On Mon 11-06-12 14:33:52, Aneesh Kumar K.V wrote: > Michal Hocko writes: > > > On Sat 09-06-12 14:29:55, Aneesh Kumar K.V wrote: > >> From: "Aneesh Kumar K.V" > >> > >> Add the hugetlb cgroup pointer to 3rd page lru.next. > > > > Interesting and I really like the idea much more than tracking by > > page_cgroup. > > > >> This limit the usage to hugetlb cgroup to only hugepages with 3 or > >> more normal pages. I guess that is an acceptable limitation. > > > > Agreed. > > > >> Signed-off-by: Aneesh Kumar K.V > > > > Other than some nits I like this. > > Thanks! > > > >> --- > >> include/linux/hugetlb_cgroup.h | 31 +++++++++++++++++++++++++++++++ > >> mm/hugetlb.c | 4 ++++ > >> 2 files changed, 35 insertions(+) > >> > >> diff --git a/include/linux/hugetlb_cgroup.h b/include/linux/hugetlb_cgroup.h > >> index 5794be4..ceff1d5 100644 > >> --- a/include/linux/hugetlb_cgroup.h > >> +++ b/include/linux/hugetlb_cgroup.h > >> @@ -26,6 +26,26 @@ struct hugetlb_cgroup { > >> }; > >> > >> #ifdef CONFIG_CGROUP_HUGETLB_RES_CTLR > >> +static inline struct hugetlb_cgroup *hugetlb_cgroup_from_page(struct page *page) > >> +{ > >> + if (!PageHuge(page)) > >> + return NULL; > >> + if (compound_order(page) < 3) > > > > Why 3? I think you wanted 2 here, right? > > Yes that should be 2. I updated that in an earlier. Already in v9 > version I have locally. ohh, I should have read replies to the patch first where you already mentioned that you are aware of that. Maybe it would be worth something like: /* Minimum page order trackable by hugetlb cgroup. * At least 3 pages are necessary for all the tracking information. */ #define HUGETLB_CGROUP_MIN_ORDER 2 > >> @@ -591,6 +592,7 @@ static void update_and_free_page(struct hstate *h, struct page *page) > >> 1 << PG_active | 1 << PG_reserved | > >> 1 << PG_private | 1 << PG_writeback); > >> } > >> + BUG_ON(hugetlb_cgroup_from_page(page)); > > > > What about VM_BUG_ON? > > Will do, So when do one decide to choose VM_BUG_ON against BUG_ON ? I think that VM_ variant is more approapriate here because it is more a debugging thing rather than a hard failure invariant. -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- 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