From: Pingfan Liu <kernelfans@gmail.com>
To: John Hubbard <jhubbard@nvidia.com>
Cc: "Michal Hocko" <mhocko@kernel.org>, Linux-MM <linux-mm@kvack.org>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
"Aneesh Kumar" <aneesh.kumar@linux.vnet.ibm.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Dan Williams" <dan.j.williams@intel.com>,
"Ralph Campbell" <rcampbell@nvidia.com>
Subject: Re: [PATCH] mm/rmap: fix the handling of device private page in try_to_unmap_one()
Date: Tue, 24 Mar 2020 11:50:26 +0800 [thread overview]
Message-ID: <CAFgQCTuUhaK=TPuAPXBMzmn8Gmy2Fbyu07g7Y6hc3QhnXVnCsw@mail.gmail.com> (raw)
In-Reply-To: <e13da747-7394-eb80-2a91-ce5eb284d1bf@nvidia.com>
On Tue, Mar 24, 2020 at 7:32 AM John Hubbard <jhubbard@nvidia.com> wrote:
>
> On 3/23/20 12:34 AM, Michal Hocko wrote:
> > On Sun 22-03-20 21:57:07, Pingfan Liu wrote:
> >> For zone_device, migration can only happen on is_device_private_page(page).
> >> Correct the logic in try_to_unmap_one().
> >
> > Maybe it is just me lacking knowledge in the zone_device ZOO. But
> > this really deserves a much more detailed explanation IMHO. It seems
> > a5430dda8a3a ("mm/migrate: support un-addressable ZONE_DEVICE page in
> > migration") deliberately made the decision to allow unmapping these
> > pages? Is the check just wrong, inncomplete? Why?
> >
> > What is the real user visible problem here?
> >
>
> I was going to guess that someone was having trouble with the behavior on
> non-device-private ZONE_DEVICE pages, but...I am also at a loss as to
> what triggered this patch. So, I have the exact same questions as Michal,
> plus really wondering what tests you are running, and on what hardware config.
:), please see my reply to Michal.
>
> It's hard to get the right CC's, but probably Dan Williams and Ralph Campbell
> should also be added, if you are sure you need this. (I'm adding them now.)
Appreciate you to do that. In fact, I am not sure about some detail,
and hope someone can correct me if I make mistake.
Thanks,
Pingfan
next prev parent reply other threads:[~2020-03-24 3:50 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-22 13:57 [PATCH] mm/rmap: fix the handling of device private page in try_to_unmap_one() Pingfan Liu
2020-03-23 7:34 ` Michal Hocko
2020-03-23 23:32 ` John Hubbard
2020-03-24 3:50 ` Pingfan Liu [this message]
2020-03-24 0:20 ` Ralph Campbell
2020-03-24 4:21 ` Pingfan Liu
2020-03-24 3:47 ` Pingfan Liu
2020-03-24 9:14 ` Michal Hocko
2020-03-25 10:54 ` Pingfan Liu
2020-04-01 14:10 ` Pingfan Liu
2020-03-24 0:04 ` Balbir Singh
2020-03-24 3:55 ` Pingfan Liu
2020-04-01 14:17 ` [PATCH] mm/rmap: fix the handling of !private device " Pingfan Liu
2020-04-01 15:58 ` Michal Hocko
2020-04-02 7:40 ` Pingfan Liu
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