From: Michal Hocko <mhocko@kernel.org>
To: "Jérôme Glisse" <jglisse@redhat.com>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, John Hubbard <jhubbard@nvidia.com>,
Dan Williams <dan.j.williams@intel.com>,
David Nellans <dnellans@nvidia.com>,
Evgeny Baskakov <ebaskakov@nvidia.com>,
Mark Hairgrove <mhairgrove@nvidia.com>,
Sherry Cheung <SCheung@nvidia.com>,
Subhash Gutti <sgutti@nvidia.com>
Subject: Re: [PATCH 09/15] mm/hmm/devmem: device memory hotplug using ZONE_DEVICE v6
Date: Fri, 28 Jul 2017 13:10:03 +0200 [thread overview]
Message-ID: <20170728111003.GA2278@dhcp22.suse.cz> (raw)
In-Reply-To: <20170628180047.5386-10-jglisse@redhat.com>
I haven't seen a newer version posted but the same comment applies on
your hmm-v25-4.9 git version from
git://people.freedesktop.org/~glisse/linux
On Wed 28-06-17 14:00:41, Jerome Glisse wrote:
> This introduce a simple struct and associated helpers for device driver
> to use when hotpluging un-addressable device memory as ZONE_DEVICE. It
> will find a unuse physical address range and trigger memory hotplug for
> it which allocates and initialize struct page for the device memory.
Please document the hotplug semantic some more please (who is in charge,
what is the lifetime, userspace API to add/remove this memory if any
etc...).
I can see you call add_pages. Please document why arch_add_memory (like
devm_memremap_pages) is not used. You also never seem to online the
range which is in line with nvdim usage and it is OK. But then I fail to
understand why you need
[...]
> + mem_hotplug_begin();
> + ret = add_pages(nid, align_start >> PAGE_SHIFT,
> + align_size >> PAGE_SHIFT, false);
> + if (ret) {
> + mem_hotplug_done();
> + goto error_add_memory;
> + }
> + move_pfn_range_to_zone(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
> + align_start >> PAGE_SHIFT,
> + align_size >> PAGE_SHIFT);
> + mem_hotplug_done();
> +
> + for (pfn = devmem->pfn_first; pfn < devmem->pfn_last; pfn++) {
> + struct page *page = pfn_to_page(pfn);
> +
> + /*
> + * ZONE_DEVICE pages union ->lru with a ->pgmap back
> + * pointer. It is a bug if a ZONE_DEVICE page is ever
> + * freed or placed on a driver-private list. Therefore,
> + * seed the storage with LIST_POISON* values.
> + */
> + list_del(&page->lru);
this? The page is not on any list yet - it hasn't been added to the page
allocator.
> + page->pgmap = &devmem->pagemap;
> + }
> + return 0;
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2017-07-28 11:10 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-28 18:00 [PATCH 00/15] HMM (Heterogeneous Memory Management) v24 Jérôme Glisse
2017-06-28 18:00 ` [PATCH 01/15] hmm: heterogeneous memory management documentation v2 Jérôme Glisse
2017-06-28 18:00 ` [PATCH 02/15] mm/hmm: heterogeneous memory management (HMM for short) v4 Jérôme Glisse
2017-06-28 18:00 ` [PATCH 03/15] mm/hmm/mirror: mirror process address space on device with HMM helpers v3 Jérôme Glisse
2017-06-28 18:00 ` [PATCH 04/15] mm/hmm/mirror: helper to snapshot CPU page table v3 Jérôme Glisse
2017-06-28 18:00 ` [PATCH 05/15] mm/hmm/mirror: device page fault handler Jérôme Glisse
2017-06-28 18:00 ` [PATCH 06/15] mm/memory_hotplug: introduce add_pages Jérôme Glisse
2017-06-28 18:00 ` [PATCH 07/15] mm/ZONE_DEVICE: new type of ZONE_DEVICE for unaddressable memory v4 Jérôme Glisse
2017-07-01 0:16 ` kbuild test robot
2017-06-28 18:00 ` [PATCH 08/15] mm/ZONE_DEVICE: special case put_page() for device private pages v2 Jérôme Glisse
2017-06-28 18:00 ` [PATCH 09/15] mm/hmm/devmem: device memory hotplug using ZONE_DEVICE v6 Jérôme Glisse
2017-07-18 21:41 ` Evgeny Baskakov
2017-07-28 11:10 ` Michal Hocko [this message]
2017-07-31 17:21 ` Jerome Glisse
2017-08-01 12:17 ` Michal Hocko
2017-06-28 18:00 ` [PATCH 10/15] mm/hmm/devmem: dummy HMM device for ZONE_DEVICE memory v3 Jérôme Glisse
2017-06-28 18:00 ` [PATCH 11/15] mm/migrate: new migrate mode MIGRATE_SYNC_NO_COPY Jérôme Glisse
2017-06-28 18:00 ` [PATCH 12/15] mm/migrate: new memory migration helper for use with device memory v4 Jérôme Glisse
2017-06-28 18:00 ` [PATCH 13/15] mm/migrate: migrate_vma() unmap page from vma while collecting pages Jérôme Glisse
2017-06-28 18:00 ` [PATCH 14/15] mm/migrate: support un-addressable ZONE_DEVICE page in migration v2 Jérôme Glisse
2017-06-28 18:00 ` [PATCH 15/15] mm/migrate: allow migrate_vma() to alloc new page on empty entry v3 Jérôme Glisse
2017-06-30 5:32 ` [PATCH 00/15] HMM (Heterogeneous Memory Management) v24 John Hubbard
2017-06-30 19:49 ` Jerome Glisse
2017-07-19 11:48 ` Yisheng Xie
2017-07-20 17:18 ` Jerome Glisse
2017-07-21 9:03 ` Yisheng Xie
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