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From:   Dan Williams <dan.j.williams@intel.com>
Date:   Wed, 26 Jun 2019 09:00:47 -0700
Message-ID: <CAPcyv4gTOf+EWzSGrFrh2GrTZt5HVR=e+xicUKEpiy57px8J+w@mail.gmail.com>
Subject: Re: [PATCH 04/25] mm: remove MEMORY_DEVICE_PUBLIC support
To:     Christoph Hellwig <hch@lst.de>
Cc:     =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= <jglisse@redhat.com>,
        Jason Gunthorpe <jgg@mellanox.com>,
        Ben Skeggs <bskeggs@redhat.com>, Linux MM <linux-mm@kvack.org>,
        nouveau@lists.freedesktop.org,
        Maling list - DRI developers 
        <dri-devel@lists.freedesktop.org>,
        linux-nvdimm <linux-nvdimm@lists.01.org>,
        linux-pci@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Michal Hocko <mhocko@suse.com>,
        "Weiny, Ira" <ira.weiny@intel.com>
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[ add Ira ]

On Wed, Jun 26, 2019 at 5:27 AM Christoph Hellwig <hch@lst.de> wrote:
>
> The code hasn't been used since it was added to the tree, and doesn't
> appear to actually be usable.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
> Acked-by: Michal Hocko <mhocko@suse.com>
[..]
> diff --git a/mm/swap.c b/mm/swap.c
> index 7ede3eddc12a..83107410d29f 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -740,17 +740,6 @@ void release_pages(struct page **pages, int nr)
>                 if (is_huge_zero_page(page))
>                         continue;
>
> -               /* Device public page can not be huge page */
> -               if (is_device_public_page(page)) {
> -                       if (locked_pgdat) {
> -                               spin_unlock_irqrestore(&locked_pgdat->lru_lock,
> -                                                      flags);
> -                               locked_pgdat = NULL;
> -                       }
> -                       put_devmap_managed_page(page);
> -                       continue;
> -               }
> -

This collides with Ira's bug fix [1]. The MEMORY_DEVICE_FSDAX case
needs this to be converted to be independent of "public" pages.
Perhaps it should be pulled out of -mm and incorporated in this
series.

[1]: https://lore.kernel.org/lkml/20190605214922.17684-1-ira.weiny@intel.com/