From: Dan Williams <dan.j.williams@intel.com>
To: Ralph Campbell <rcampbell@nvidia.com>
Cc: Linux MM <linux-mm@kvack.org>,
kvm-ppc@vger.kernel.org, nouveau@lists.freedesktop.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Ira Weiny <ira.weiny@intel.com>,
Matthew Wilcox <willy@infradead.org>,
Jerome Glisse <jglisse@redhat.com>,
John Hubbard <jhubbard@nvidia.com>,
Alistair Popple <apopple@nvidia.com>,
Christoph Hellwig <hch@lst.de>, Jason Gunthorpe <jgg@nvidia.com>,
Zi Yan <ziy@nvidia.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Yang Shi <yang.shi@linux.alibaba.com>,
Paul Mackerras <paulus@ozlabs.org>,
Ben Skeggs <bskeggs@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v2] mm/hmm: make device private reference counts zero based
Date: Mon, 12 Oct 2020 14:14:07 -0700 [thread overview]
Message-ID: <CAPcyv4ijD+=3rje1CfSG4XKuRNfuAWOui93NQV09NmBte_gc0w@mail.gmail.com> (raw)
In-Reply-To: <20201012174540.17328-1-rcampbell@nvidia.com>
On Mon, Oct 12, 2020 at 10:46 AM Ralph Campbell <rcampbell@nvidia.com> wrote:
>
> ZONE_DEVICE struct pages have an extra reference count that complicates the
> code for put_page() and several places in the kernel that need to check the
> reference count to see that a page is not being used (gup, compaction,
> migration, etc.). Clean up the code so the reference count doesn't need to
> be treated specially for device private pages, leaving DAX as still being
> a special case.
Please no half-step to removing the special casing...
[..]
> +void free_zone_device_page(struct page *page)
> +{
> + if (!is_device_private_page(page))
> return;
That seems too subtle to be acceptable to me. All ZONE_DEVICE pages
need to have the same relationship with respect to idle-ness and the
page reference count.
next prev parent reply other threads:[~2020-10-12 21:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-12 17:45 [PATCH v2] mm/hmm: make device private reference counts zero based Ralph Campbell
2020-10-12 21:14 ` Dan Williams [this message]
2020-10-15 7:44 ` Christoph Hellwig
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