From: Michal Hocko <mhocko@suse.cz>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
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
Subject: Re: [PATCH -V8 11/16] hugetlb/cgroup: Add charge/uncharge routines for hugetlb cgroup
Date: Mon, 11 Jun 2012 14:59:52 +0200 [thread overview]
Message-ID: <20120611125952.GM12402@tiehlicka.suse.cz> (raw)
In-Reply-To: <87liju5h9u.fsf@skywalker.in.ibm.com>
On Mon 11-06-12 14:58:45, Aneesh Kumar K.V wrote:
> Michal Hocko <mhocko@suse.cz> writes:
>
> > On Sat 09-06-12 14:29:56, Aneesh Kumar K.V wrote:
> >> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
> >>
> >> This patchset add the charge and uncharge routines for hugetlb cgroup.
> >> This will be used in later patches when we allocate/free HugeTLB
> >> pages.
> >
> > Please describe the locking rules.
>
> All the update happen within hugetlb_lock.
Yes, I figured but it is definitely worth mentioning in the patch
description.
[...]
> >> +void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
> >> + struct hugetlb_cgroup *h_cg,
> >> + struct page *page)
> >> +{
> >> + if (hugetlb_cgroup_disabled() || !h_cg)
> >> + return;
> >> +
> >> + spin_lock(&hugetlb_lock);
> >> + if (hugetlb_cgroup_from_page(page)) {
> >
> > How can this happen? Is it possible that two CPUs are trying to charge
> > one page?
>
> That is why I added that. I looked at the alloc_huge_page, and I
> don't see we would end with same page from different CPUs but then
> we have similar checks in memcg, where we drop the charge if we find
> the page cgroup already used.
Yes but memcg is little bit more complicated than hugetlb which has
which doesn't have to cope with async charges. Hugetlb allocation is
serialized by hugetlb_lock so only one caller gets the page.
I do not think the check is required here or add a comment explaining
how it can happen.
[...]
--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
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next prev parent reply other threads:[~2012-06-11 12:59 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-09 8:59 [PATCH -V8 00/16] hugetlb: Add HugeTLB controller to control HugeTLB allocation Aneesh Kumar K.V
2012-06-09 8:59 ` [PATCH -V8 01/16] hugetlb: rename max_hstate to hugetlb_max_hstate Aneesh Kumar K.V
2012-06-09 8:59 ` [PATCH -V8 02/16] hugetlb: don't use ERR_PTR with VM_FAULT* values Aneesh Kumar K.V
2012-06-09 11:10 ` Konrad Rzeszutek Wilk
2012-06-09 13:17 ` Aneesh Kumar K.V
2012-06-09 19:28 ` KOSAKI Motohiro
2012-06-10 1:59 ` Hillf Danton
2012-06-09 8:59 ` [PATCH -V8 03/16] hugetlb: add an inline helper for finding hstate index Aneesh Kumar K.V
2012-06-09 8:59 ` [PATCH -V8 04/16] hugetlb: use mmu_gather instead of a temporary linked list for accumulating pages Aneesh Kumar K.V
2012-06-09 8:59 ` [PATCH -V8 05/16] hugetlb: avoid taking i_mmap_mutex in unmap_single_vma() for hugetlb Aneesh Kumar K.V
2012-06-09 9:44 ` Johannes Weiner
2012-06-09 13:03 ` Aneesh Kumar K.V
2012-06-09 14:49 ` Johannes Weiner
2012-06-09 8:59 ` [PATCH -V8 06/16] hugetlb: simplify migrate_huge_page() Aneesh Kumar K.V
2012-06-12 7:31 ` Kamezawa Hiroyuki
2012-06-09 8:59 ` [PATCH -V8 07/16] hugetlb: add a list for tracking in-use HugeTLB pages Aneesh Kumar K.V
2012-06-09 8:59 ` [PATCH -V8 08/16] hugetlb: Make some static variables global Aneesh Kumar K.V
2012-06-12 7:35 ` Kamezawa Hiroyuki
2012-06-09 8:59 ` [PATCH -V8 09/16] mm/hugetlb: Add new HugeTLB cgroup Aneesh Kumar K.V
2012-06-12 7:46 ` Kamezawa Hiroyuki
2012-06-12 9:37 ` Aneesh Kumar K.V
2012-06-09 8:59 ` [PATCH -V8 10/16] hugetlb/cgroup: Add the cgroup pointer to page lru Aneesh Kumar K.V
2012-06-09 11:14 ` Konrad Rzeszutek Wilk
2012-06-09 17:04 ` Aneesh Kumar K.V
2012-06-11 8:16 ` Michal Hocko
2012-06-11 9:03 ` Aneesh Kumar K.V
2012-06-11 9:16 ` Michal Hocko
2012-06-11 9:33 ` Aneesh Kumar K.V
2012-06-11 8:41 ` Kamezawa Hiroyuki
2012-06-12 7:52 ` Kamezawa Hiroyuki
2012-06-12 9:40 ` Aneesh Kumar K.V
2012-06-09 8:59 ` [PATCH -V8 11/16] hugetlb/cgroup: Add charge/uncharge routines for hugetlb cgroup Aneesh Kumar K.V
2012-06-11 8:38 ` Michal Hocko
2012-06-11 9:10 ` Michal Hocko
2012-06-11 9:28 ` Aneesh Kumar K.V
2012-06-11 12:59 ` Michal Hocko [this message]
2012-06-11 15:35 ` Aneesh Kumar K.V
2012-06-12 8:08 ` Kamezawa Hiroyuki
2012-06-12 10:50 ` Aneesh Kumar K.V
2012-06-13 11:02 ` Kamezawa Hiroyuki
2012-06-09 8:59 ` [PATCH -V8 12/16] hugetlb/cgroup: Add support for cgroup removal Aneesh Kumar K.V
2012-06-11 8:52 ` Michal Hocko
2012-06-11 9:40 ` Aneesh Kumar K.V
2012-06-11 13:14 ` Michal Hocko
2012-06-11 15:34 ` Aneesh Kumar K.V
2012-06-12 8:23 ` Kamezawa Hiroyuki
2012-06-12 10:52 ` Aneesh Kumar K.V
2012-06-09 8:59 ` [PATCH -V8 13/16] hugetlb/cgroup: add hugetlb cgroup control files Aneesh Kumar K.V
2012-06-09 11:19 ` Konrad Rzeszutek Wilk
2012-06-11 9:02 ` Michal Hocko
2012-06-11 9:43 ` Aneesh Kumar K.V
2012-06-11 13:15 ` Michal Hocko
2012-06-12 8:35 ` Kamezawa Hiroyuki
2012-06-12 10:58 ` Aneesh Kumar K.V
2012-06-13 0:16 ` Kamezawa Hiroyuki
2012-06-09 8:59 ` [PATCH -V8 14/16] hugetlb/cgroup: add charge/uncharge calls for HugeTLB alloc/free Aneesh Kumar K.V
2012-06-09 9:23 ` Johannes Weiner
2012-06-09 13:09 ` Aneesh Kumar K.V
2012-06-09 14:30 ` Johannes Weiner
2012-06-09 15:55 ` Aneesh Kumar K.V
2012-06-11 9:19 ` Michal Hocko
2012-06-11 9:21 ` Michal Hocko
2012-06-11 10:29 ` Aneesh Kumar K.V
2012-06-09 9:00 ` [PATCH -V8 15/16] hugetlb/cgroup: migrate hugetlb cgroup info from oldpage to new page during migration Aneesh Kumar K.V
2012-06-11 9:24 ` Michal Hocko
2012-06-11 10:17 ` Aneesh Kumar K.V
2012-06-12 8:51 ` Kamezawa Hiroyuki
2012-06-12 11:00 ` Aneesh Kumar K.V
2012-06-13 11:15 ` Kamezawa Hiroyuki
2012-06-09 9:00 ` [PATCH -V8 16/16] hugetlb/cgroup: add HugeTLB controller documentation Aneesh Kumar K.V
2012-06-12 8:57 ` Kamezawa Hiroyuki
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