From: Felix Kuehling <felix.kuehling@amd.com>
To: Jason Gunthorpe <jgg@nvidia.com>, David Hildenbrand <david@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>,
Christoph Hellwig <hch@lst.de>, Alex Sierra <alex.sierra@amd.com>,
akpm@linux-foundation.org, linux-mm@kvack.org,
rcampbell@nvidia.com, linux-ext4@vger.kernel.org,
linux-xfs@vger.kernel.org, amd-gfx@lists.freedesktop.org,
dri-devel@lists.freedesktop.org, jglisse@redhat.com,
willy@infradead.org
Subject: Re: [PATCH v6 01/10] mm: add zone device coherent type memory support
Date: Thu, 17 Feb 2022 16:12:20 -0500 [thread overview]
Message-ID: <bf16195e-2570-3687-2b53-3f597ebfcfec@amd.com> (raw)
In-Reply-To: <20220216122600.GG4160@nvidia.com>
Am 2022-02-16 um 07:26 schrieb Jason Gunthorpe:
> The other place that needs careful audit is all the callers using
> vm_normal_page() - they must all be able to accept a ZONE_DEVICE page
> if we don't set pte_devmap.
How much code are we talking about here? A quick search finds 26
call-sites in 12 files in current master:
fs/proc/task_mmu.c
mm/hmm.c
mm/gup.c
mm/huge_memory.c (vm_normal_page_pmd)
mm/khugepaged.c
mm/madvise.c
mm/mempolicy.c
mm/memory.c
mm/mlock.c
mm/migrate.c
mm/mprotect.c
mm/memcontrol.c
I'm thinking of a more theoretical approach: Instead of auditing all
users, I'd ask, what are the invariants that a vm_normal_page should
have. Then check, whether our DEVICE_COHERENT pages satisfy them. But
maybe the concept of a vm_normal_page isn't defined clearly enough for that.
That said, I think we (Alex and myself) made an implicit assumption from
the start, that a DEVICE_COHERENT page should behave a lot like a normal
page in terms of VMA mappings, even if we didn't know what that means in
detail.
I can now at least name some differences between DEVICE_COHERENT and
normal pages: how the memory is allocated, how data is migrated into
DEVICE_COHERENT pages and that it can't be on any LRU list (because the
lru list_head in struct page is aliased by pgmap and zone_device_data).
Maybe I'll find more differences if I keep digging.
Regards,
Felix
>
> Jason
next prev parent reply other threads:[~2022-02-17 21:12 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-01 15:48 [PATCH v6 00/10] Add MEMORY_DEVICE_COHERENT for coherent device memory mapping Alex Sierra
2022-02-01 15:48 ` [PATCH v6 01/10] mm: add zone device coherent type memory support Alex Sierra
2022-02-11 16:15 ` David Hildenbrand
2022-02-11 16:39 ` David Hildenbrand
2022-02-11 16:52 ` Sierra Guiza, Alejandro (Alex)
2022-02-11 17:07 ` Felix Kuehling
2022-02-15 12:16 ` David Hildenbrand
2022-02-15 14:45 ` Jason Gunthorpe
2022-02-15 18:32 ` Christoph Hellwig
2022-02-15 19:41 ` Jason Gunthorpe
2022-02-15 21:35 ` Felix Kuehling
2022-02-15 21:47 ` Jason Gunthorpe
2022-02-15 22:49 ` Felix Kuehling
2022-02-16 2:01 ` Jason Gunthorpe
2022-02-16 16:56 ` Felix Kuehling
2022-02-16 17:28 ` Jason Gunthorpe
2022-02-16 1:23 ` Alistair Popple
2022-02-16 2:03 ` Jason Gunthorpe
2022-02-16 2:36 ` Alistair Popple
2022-02-16 8:31 ` David Hildenbrand
2022-02-16 12:26 ` Jason Gunthorpe
2022-02-17 1:05 ` Alistair Popple
2022-02-17 21:12 ` Felix Kuehling [this message]
2022-02-18 0:19 ` Jason Gunthorpe
2022-02-18 19:20 ` Felix Kuehling
2022-02-18 19:26 ` Jason Gunthorpe
2022-02-18 19:37 ` Felix Kuehling
2022-02-28 20:34 ` [PATCH] mm: split vm_normal_pages for LRU and non-LRU handling Alex Sierra
2022-02-28 22:41 ` Felix Kuehling
2022-03-01 8:03 ` David Hildenbrand
2022-03-01 16:08 ` Felix Kuehling
2022-03-01 16:22 ` David Hildenbrand
2022-03-01 16:30 ` Felix Kuehling
2022-03-01 16:32 ` David Hildenbrand
2022-02-18 0:59 ` [PATCH v6 01/10] mm: add zone device coherent type memory support Alistair Popple
2022-02-11 16:45 ` Jason Gunthorpe
2022-02-11 16:49 ` David Hildenbrand
2022-02-11 16:56 ` Jason Gunthorpe
2022-02-15 12:15 ` David Hildenbrand
2022-02-15 18:52 ` Felix Kuehling
2022-02-11 17:05 ` Felix Kuehling
2022-02-14 2:04 ` Alistair Popple
2022-02-01 15:48 ` [PATCH v6 02/10] mm: add device coherent vma selection for memory migration Alex Sierra
2022-02-01 15:48 ` [PATCH v6 03/10] mm/gup: fail get_user_pages for LONGTERM dev coherent type Alex Sierra
2022-02-01 15:48 ` [PATCH v6 04/10] drm/amdkfd: add SPM support for SVM Alex Sierra
2022-02-01 15:48 ` [PATCH v6 05/10] drm/amdkfd: coherent type as sys mem on migration to ram Alex Sierra
2022-02-01 15:48 ` [PATCH v6 06/10] lib: test_hmm add ioctl to get zone device type Alex Sierra
2022-02-01 15:48 ` [PATCH v6 07/10] lib: test_hmm add module param for " Alex Sierra
2022-02-01 15:48 ` [PATCH v6 08/10] lib: add support for device coherent type in test_hmm Alex Sierra
2022-02-01 15:49 ` [PATCH v6 09/10] tools: update hmm-test to support device coherent type Alex Sierra
2022-02-01 15:49 ` [PATCH v6 10/10] tools: update test_hmm script to support SP config Alex Sierra
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