From: Dan Williams <dan.j.williams@intel.com>
To: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Linux MM <linux-mm@kvack.org>, John Hubbard <jhubbard@nvidia.com>,
David Nellans <dnellans@nvidia.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>
Subject: Re: [HMM 07/15] mm/ZONE_DEVICE: new type of ZONE_DEVICE for unaddressable memory v2
Date: Mon, 22 May 2017 14:17:56 -0700 [thread overview]
Message-ID: <CAPcyv4jJh8G7y-Gr-54iBVGrGDQwu=M=FXtkSpXyd=2oNqPcWA@mail.gmail.com> (raw)
In-Reply-To: <20170522165206.6284-8-jglisse@redhat.com>
On Mon, May 22, 2017 at 9:51 AM, Jérôme Glisse <jglisse@redhat.com> wrote:
> HMM (heterogeneous memory management) need struct page to support migration
> from system main memory to device memory. Reasons for HMM and migration to
> device memory is explained with HMM core patch.
>
> This patch deals with device memory that is un-addressable memory (ie CPU
> can not access it). Hence we do not want those struct page to be manage
> like regular memory. That is why we extend ZONE_DEVICE to support different
> types of memory.
>
> A persistent memory type is define for existing user of ZONE_DEVICE and a
> new device un-addressable type is added for the un-addressable memory type.
> There is a clear separation between what is expected from each memory type
> and existing user of ZONE_DEVICE are un-affected by new requirement and new
> use of the un-addressable type. All specific code path are protect with
> test against the memory type.
>
> Because memory is un-addressable we use a new special swap type for when
> a page is migrated to device memory (this reduces the number of maximum
> swap file).
>
> The main two additions beside memory type to ZONE_DEVICE is two callbacks.
> First one, page_free() is call whenever page refcount reach 1 (which means
> the page is free as ZONE_DEVICE page never reach a refcount of 0). This
> allow device driver to manage its memory and associated struct page.
>
> The second callback page_fault() happens when there is a CPU access to
> an address that is back by a device page (which are un-addressable by the
> CPU). This callback is responsible to migrate the page back to system
> main memory. Device driver can not block migration back to system memory,
> HMM make sure that such page can not be pin into device memory.
>
> If device is in some error condition and can not migrate memory back then
> a CPU page fault to device memory should end with SIGBUS.
>
> Changed since v1:
> - rename to device private memory (from device unaddressable)
>
> Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
[..]
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 229afe3..d49d816 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -737,6 +737,19 @@ config ZONE_DEVICE
>
> If FS_DAX is enabled, then say Y.
>
> +config DEVICE_UNADDRESSABLE
> + bool "Unaddressable device memory (GPU memory, ...)"
> + depends on X86_64
> + depends on ZONE_DEVICE
> + depends on MEMORY_HOTPLUG
> + depends on MEMORY_HOTREMOVE
> + depends on SPARSEMEM_VMEMMAP
> +
> + help
> + Allows creation of struct pages to represent unaddressable device
> + memory; i.e., memory that is only accessible from the device (or
> + group of devices).
Lets change config symbol naming from "device un-addressable memory"
to "device private memory" the same way we did for the code symbols.
With that change you can add:
Acked-by: Dan Williams <dan.j.williams@intel.com>
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next prev parent reply other threads:[~2017-05-22 21:17 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-22 16:51 [HMM 00/15] HMM (Heterogeneous Memory Management) v22 Jérôme Glisse
2017-05-22 16:51 ` [HMM 01/15] hmm: heterogeneous memory management documentation Jérôme Glisse
2017-05-22 16:51 ` [HMM 02/15] mm/hmm: heterogeneous memory management (HMM for short) v3 Jérôme Glisse
2017-05-22 16:51 ` [HMM 03/15] mm/hmm/mirror: mirror process address space on device with HMM helpers v3 Jérôme Glisse
2017-05-22 16:51 ` [HMM 04/15] mm/hmm/mirror: helper to snapshot CPU page table v3 Jérôme Glisse
2017-05-22 16:51 ` [HMM 05/15] mm/hmm/mirror: device page fault handler Jérôme Glisse
2017-05-22 16:51 ` [HMM 06/15] mm/memory_hotplug: introduce add_pages Jérôme Glisse
2017-05-22 16:51 ` [HMM 07/15] mm/ZONE_DEVICE: new type of ZONE_DEVICE for unaddressable memory v2 Jérôme Glisse
2017-05-22 21:17 ` Dan Williams [this message]
2017-05-23 21:36 ` [HMM 07/18] mm/ZONE_DEVICE: new type of ZONE_DEVICE for unaddressable memory v3 Jérôme Glisse
2017-05-23 8:36 ` [HMM 07/15] mm/ZONE_DEVICE: new type of ZONE_DEVICE for unaddressable memory v2 kbuild test robot
2017-05-22 16:51 ` [HMM 08/15] mm/ZONE_DEVICE: special case put_page() for device private pages Jérôme Glisse
2017-05-22 19:29 ` Dan Williams
2017-05-22 20:14 ` Jerome Glisse
2017-05-22 20:19 ` Dan Williams
2017-05-22 21:14 ` Jerome Glisse
2017-05-22 20:22 ` Hugh Dickins
2017-05-22 21:17 ` Jerome Glisse
2017-05-23 9:34 ` kbuild test robot
2017-05-23 13:23 ` Kirill A. Shutemov
2017-05-23 21:37 ` [HMM 08/18] mm/ZONE_DEVICE: special case put_page() for device private pages v2 Jérôme Glisse
2017-05-22 16:52 ` [HMM 09/15] mm/hmm/devmem: device memory hotplug using ZONE_DEVICE v4 Jérôme Glisse
2017-05-23 21:37 ` [HMM 09/18] mm/hmm/devmem: device memory hotplug using ZONE_DEVICE v5 Jérôme Glisse
2017-05-22 16:52 ` [HMM 10/15] mm/hmm/devmem: dummy HMM device for ZONE_DEVICE memory v3 Jérôme Glisse
2017-05-22 16:52 ` [HMM 11/15] mm/migrate: new migrate mode MIGRATE_SYNC_NO_COPY Jérôme Glisse
2017-05-22 16:52 ` [HMM 12/15] mm/migrate: new memory migration helper for use with device memory v4 Jérôme Glisse
2017-05-23 18:07 ` Reza Arbab
2017-06-27 0:07 ` Evgeny Baskakov
2017-06-30 23:19 ` Evgeny Baskakov
2017-07-01 0:57 ` Jerome Glisse
2017-07-01 2:06 ` Evgeny Baskakov
2017-07-10 22:59 ` Evgeny Baskakov
2017-07-10 23:43 ` Jerome Glisse
2017-07-11 0:17 ` Evgeny Baskakov
2017-07-11 0:54 ` Jerome Glisse
2017-07-20 21:05 ` Evgeny Baskakov
2017-07-10 23:44 ` Evgeny Baskakov
2017-07-11 18:29 ` Jerome Glisse
2017-07-11 18:42 ` Evgeny Baskakov
2017-07-11 18:49 ` Jerome Glisse
2017-07-11 19:35 ` Evgeny Baskakov
2017-07-13 20:16 ` Jerome Glisse
2017-07-14 5:32 ` Evgeny Baskakov
2017-07-14 19:43 ` Evgeny Baskakov
2017-07-15 0:55 ` Jerome Glisse
2017-07-15 5:04 ` Evgeny Baskakov
2017-07-21 1:00 ` Evgeny Baskakov
2017-07-21 1:33 ` Jerome Glisse
2017-07-21 22:01 ` Evgeny Baskakov
2017-07-25 22:45 ` Evgeny Baskakov
2017-07-26 19:14 ` Jerome Glisse
2017-05-22 16:52 ` [HMM 13/15] mm/migrate: migrate_vma() unmap page from vma while collecting pages Jérôme Glisse
2017-05-22 16:52 ` [HMM 14/15] mm/migrate: support un-addressable ZONE_DEVICE page in migration v2 Jérôme Glisse
2017-05-22 16:52 ` [HMM 15/15] mm/migrate: allow migrate_vma() to alloc new page on empty entry v2 Jérôme Glisse
2017-05-23 22:02 ` [HMM 00/15] HMM (Heterogeneous Memory Management) v22 Jerome Glisse
2017-05-23 22:05 ` Andrew Morton
2017-05-24 1:55 ` Balbir Singh
2017-05-24 17:53 ` Jerome Glisse
2017-06-01 2:04 ` Balbir Singh
2017-06-01 22:38 ` Jerome Glisse
2017-06-03 9:18 ` Balbir Singh
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