From: Ira Weiny <ira.weiny@intel.com>
To: John Hubbard <jhubbard@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Dan Williams <dan.j.williams@intel.com>
Subject: Re: [PATCH v2 02/11] mm/hmm: use reference counting for HMM struct v2
Date: Thu, 28 Mar 2019 09:57:09 -0700 [thread overview]
Message-ID: <20190328165708.GH31324@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <fcb7be01-38c1-ed1f-70a0-d03dc9260473@nvidia.com>
On Thu, Mar 28, 2019 at 05:39:26PM -0700, John Hubbard wrote:
> On 3/28/19 2:21 PM, Jerome Glisse wrote:
> > On Thu, Mar 28, 2019 at 01:43:13PM -0700, John Hubbard wrote:
> >> On 3/28/19 12:11 PM, Jerome Glisse wrote:
> >>> On Thu, Mar 28, 2019 at 04:07:20AM -0700, Ira Weiny wrote:
> >>>> On Mon, Mar 25, 2019 at 10:40:02AM -0400, Jerome Glisse wrote:
> >>>>> From: Jérôme Glisse <jglisse@redhat.com>
> [...]
> >>>>> @@ -67,14 +78,9 @@ struct hmm {
> >>>>> */
> >>>>> static struct hmm *hmm_register(struct mm_struct *mm)
> >>>>> {
> >>>>> - struct hmm *hmm = READ_ONCE(mm->hmm);
> >>>>> + struct hmm *hmm = mm_get_hmm(mm);
> >>>>
> >>>> FWIW: having hmm_register == "hmm get" is a bit confusing...
> >>>
> >>> The thing is that you want only one hmm struct per process and thus
> >>> if there is already one and it is not being destroy then you want to
> >>> reuse it.
> >>>
> >>> Also this is all internal to HMM code and so it should not confuse
> >>> anyone.
> >>>
> >>
> >> Well, it has repeatedly come up, and I'd claim that it is quite
> >> counter-intuitive. So if there is an easy way to make this internal
> >> HMM code clearer or better named, I would really love that to happen.
> >>
> >> And we shouldn't ever dismiss feedback based on "this is just internal
> >> xxx subsystem code, no need for it to be as clear as other parts of the
> >> kernel", right?
> >
> > Yes but i have not seen any better alternative that present code. If
> > there is please submit patch.
> >
>
> Ira, do you have any patch you're working on, or a more detailed suggestion there?
> If not, then I might (later, as it's not urgent) propose a small cleanup patch
> I had in mind for the hmm_register code. But I don't want to duplicate effort
> if you're already thinking about it.
No I don't have anything.
I was just really digging into these this time around and I was about to
comment on the lack of "get's" for some "puts" when I realized that
"hmm_register" _was_ the get...
:-(
Ira
>
>
> thanks,
> --
> John Hubbard
> NVIDIA
>
>
next prev parent reply other threads:[~2019-03-29 0:58 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-25 14:40 [PATCH v2 00/11] Improve HMM driver API v2 jglisse
2019-03-25 14:40 ` [PATCH v2 01/11] mm/hmm: select mmu notifier when selecting HMM jglisse
2019-03-28 20:33 ` John Hubbard
2019-03-29 21:15 ` Jerome Glisse
2019-03-29 21:42 ` John Hubbard
2019-03-25 14:40 ` [PATCH v2 02/11] mm/hmm: use reference counting for HMM struct v2 jglisse
2019-03-28 11:07 ` Ira Weiny
2019-03-28 19:11 ` Jerome Glisse
2019-03-28 20:43 ` John Hubbard
2019-03-28 21:21 ` Jerome Glisse
2019-03-29 0:39 ` John Hubbard
2019-03-28 16:57 ` Ira Weiny [this message]
2019-03-29 1:00 ` Jerome Glisse
2019-03-29 1:18 ` John Hubbard
2019-03-29 1:50 ` Jerome Glisse
2019-03-28 18:21 ` Ira Weiny
2019-03-29 2:25 ` Jerome Glisse
2019-03-29 20:07 ` John Hubbard
2019-03-29 2:11 ` John Hubbard
2019-03-29 2:22 ` Jerome Glisse
2019-03-25 14:40 ` [PATCH v2 03/11] mm/hmm: do not erase snapshot when a range is invalidated jglisse
2019-03-25 14:40 ` [PATCH v2 04/11] mm/hmm: improve and rename hmm_vma_get_pfns() to hmm_range_snapshot() v2 jglisse
2019-03-28 13:30 ` Ira Weiny
2019-03-25 14:40 ` [PATCH v2 05/11] mm/hmm: improve and rename hmm_vma_fault() to hmm_range_fault() v2 jglisse
2019-03-28 13:43 ` Ira Weiny
2019-03-28 22:03 ` Jerome Glisse
2019-03-25 14:40 ` [PATCH v2 06/11] mm/hmm: improve driver API to work and wait over a range v2 jglisse
2019-03-28 13:11 ` Ira Weiny
2019-03-28 21:39 ` Jerome Glisse
2019-03-28 16:12 ` Ira Weiny
2019-03-29 0:56 ` Jerome Glisse
2019-03-28 18:49 ` Ira Weiny
2019-03-25 14:40 ` [PATCH v2 07/11] mm/hmm: add default fault flags to avoid the need to pre-fill pfns arrays jglisse
2019-03-28 21:59 ` John Hubbard
2019-03-28 22:12 ` Jerome Glisse
2019-03-28 22:19 ` John Hubbard
2019-03-28 22:31 ` Jerome Glisse
2019-03-28 22:40 ` John Hubbard
2019-03-28 23:21 ` Jerome Glisse
2019-03-28 23:28 ` John Hubbard
2019-03-28 16:42 ` Ira Weiny
2019-03-29 1:17 ` Jerome Glisse
2019-03-29 1:30 ` John Hubbard
2019-03-29 1:42 ` Jerome Glisse
2019-03-29 1:59 ` Jerome Glisse
2019-03-29 2:05 ` John Hubbard
2019-03-29 2:12 ` Jerome Glisse
2019-03-28 23:43 ` Jerome Glisse
2019-03-25 14:40 ` [PATCH v2 08/11] mm/hmm: mirror hugetlbfs (snapshoting, faulting and DMA mapping) v2 jglisse
2019-03-28 16:53 ` Ira Weiny
2019-03-25 14:40 ` [PATCH v2 09/11] mm/hmm: allow to mirror vma of a file on a DAX backed filesystem v2 jglisse
2019-03-28 18:04 ` Ira Weiny
2019-03-29 2:17 ` Jerome Glisse
2019-03-25 14:40 ` [PATCH v2 10/11] mm/hmm: add helpers for driver to safely take the mmap_sem v2 jglisse
2019-03-28 20:54 ` John Hubbard
2019-03-28 21:30 ` Jerome Glisse
2019-03-28 21:41 ` John Hubbard
2019-03-28 22:08 ` Jerome Glisse
2019-03-28 22:25 ` John Hubbard
2019-03-28 22:40 ` Jerome Glisse
2019-03-28 22:43 ` John Hubbard
2019-03-28 23:05 ` Jerome Glisse
2019-03-28 23:20 ` John Hubbard
2019-03-28 23:24 ` Jerome Glisse
2019-03-28 23:34 ` John Hubbard
2019-03-28 18:44 ` Ira Weiny
2019-03-25 14:40 ` [PATCH v2 11/11] mm/hmm: add an helper function that fault pages and map them to a device v2 jglisse
2019-04-01 11:59 ` Souptick Joarder
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