Re: [PATCH v9 07/10] mm: Device exclusive memory access

ce exclusive access? Do we have any numbers for the worst case page fault latency when something is marked away for exclusive access? I presume for now this is anonymous memory only? SWP_DEVICE_EXCLUSIVE would only impact the address space of programs using the GPU. Should the exclusively marked range live i

Re: [PATCH v9 07/10] mm: Device exclusive memory access

On Wed, May 26, 2021 at 12:17:18AM -0700, John Hubbard wrote: > On 5/25/21 4:51 AM, Balbir Singh wrote: > ... > > > How beneficial is this code to nouveau users? I see that it permits a > > > part of OpenCL to be implemented, but how useful/important is this in > > &

Re: [RFC 00/11] THP support for zone device pages

On 3/7/25 10:08, Matthew Brost wrote: > On Thu, Mar 06, 2025 at 03:42:28PM +1100, Balbir Singh wrote: > > This is an exciting series to see. As of today, we have just merged this > series into the DRM subsystem / Xe [2], which adds very basic SVM > support. One of the performance

[RFC 02/11] mm/migrate_device: flags for selecting device private THP pages

Add flags to mark zone device migration pages. MIGRATE_VMA_SELECT_COMPOUND will be used to select THP pages during migrate_vma_setup() and MIGRATE_PFN_COMPOUND will make migrating device pages as compound pages during device pfn migration. Signed-off-by: Balbir Singh --- include/linux

[RFC 08/11] mm/thp: add split during migration support

code paths, an extra reference count is added to the split folio pages, which will be dropped in the finalize phase. Signed-off-by: Balbir Singh --- include/linux/huge_mm.h | 11 ++-- mm/huge_memory.c| 53 +--- mm/migrate_device.c | 60

[RFC 09/11] lib/test_hmm: add test case for split pages

Add a new flag HMM_DMIRROR_FLAG_FAIL_ALLOC to emulate failure of allocating a large page. This tests the code paths involving split migration. Signed-off-by: Balbir Singh --- lib/test_hmm.c | 12 +++- lib/test_hmm_uapi.h | 3 +++ 2 files changed, 14 insertions(+), 1 deletion

[RFC 06/11] lib/test_hmm: test cases and support for zone device private THP

will be added in future patches in this series. Signed-off-by: Balbir Singh --- lib/test_hmm.c | 342 +++-- 1 file changed, 273 insertions(+), 69 deletions(-) diff --git a/lib/test_hmm.c b/lib/test_hmm.c index 5b144bc5c4ec..a81d2f8a0426 100644 --- a/lib

[RFC 11/11] gpu/drm/nouveau: Add THP migration support

Change the code to add support for MIGRATE_VMA_SELECT_COMPOUND and appropriately handling page sizes in the migrate/evict code paths. Signed-off-by: Balbir Singh --- drivers/gpu/drm/nouveau/nouveau_dmem.c | 244 + drivers/gpu/drm/nouveau/nouveau_svm.c | 6 +- drivers

[RFC 10/11] selftests/mm/hmm-tests: new tests for zone device THP migration

Add new tests for migrating anon THP pages, including anon_huge, anon_huge_zero and error cases involving forced splitting of pages during migration. Signed-off-by: Balbir Singh --- tools/testing/selftests/mm/hmm-tests.c | 407 + 1 file changed, 407 insertions(+) diff

[RFC 07/11] mm/memremap: Add folio_split support

requires a mechanism of reorganizing the backing pages (backing pages are used to create a mirror device) again into the right sized order pages. This is supported by exporting prep_compound_page(). Signed-off-by: Balbir Singh --- include/linux/memremap.h | 7 +++ include/linux/mm.h

[RFC 05/11] mm/memory/fault: Add support for zone device THP fault handling

When the CPU touches a zone device THP entry, the data needs to be migrated back to the CPU, call migrate_to_ram() on these pages via do_huge_pmd_device_private() fault handling helper. Signed-off-by: Balbir Singh --- include/linux/huge_mm.h | 7 +++ mm/huge_memory.c| 35

[RFC 04/11] mm/migrate_device: THP migration of zone device pages

re is fallback support to split the folio and migrate it. migrate_vma_insert_huge_pmd_page() closely follows the logic of migrate_vma_insert_page() Support for splitting pages as needed for migration will follow in later patches in this series. Signed-off-by: Balbir Singh --- mm/migrate_device.c

[RFC 00/11] THP support for zone device pages

c: Matthew Wilcox Cc: Peter Xu Cc: Zi Yan Cc: Kefeng Wang Cc: Jane Chu Cc: Alistair Popple Cc: Donet Tom Balbir Singh (11): mm/zone_device: support large zone device private folios mm/migrate_device: flags for selecting device private THP pages mm/thp: zone_device awareness in THP han

[RFC 03/11] mm/thp: zone_device awareness in THP handling code

. try_to_map_to_unused_zeropage() does not apply to zone device entries, zone device entries are ignored in the call. Signed-off-by: Balbir Singh --- mm/huge_memory.c | 151 +++ mm/migrate.c | 2 + mm/page_vma_mapped.c | 10 +++ mm/rmap.c| 19 +- 4

[RFC 01/11] mm/zone_device: support large zone device private folios

freed, this is true for both PAGE_SIZE and higher order pages. Signed-off-by: Balbir Singh --- include/linux/memremap.h | 22 +- mm/memremap.c| 50 +--- 2 files changed, 58 insertions(+), 14 deletions(-) diff --git a/include/linux

Re: [RFC 04/11] mm/migrate_device: THP migration of zone device pages

On 3/6/25 20:24, Mika Penttilä wrote: > Hi, > > On 3/6/25 06:42, Balbir Singh wrote: > ... > >> >> /* >> * The only time there is no vma is when called from >> @@ -728,15 +1000,47 @@ static void __migrate_d

Re: [RFC 07/11] mm/memremap: Add folio_split support

On 3/6/25 19:16, Mika Penttilä wrote: > Hi, > > On 3/6/25 06:42, Balbir Singh wrote: >> When a zone device page is split (via huge pmd folio split). The >> driver callback for folio_split is invoked to let the device driver >> know that the folio size has been

Re: [RFC 01/11] mm/zone_device: support large zone device private folios

On 7/8/25 23:37, David Hildenbrand wrote: > On 06.03.25 05:42, Balbir Singh wrote: >> Add routines to support allocation of large order zone device folios >> and helper functions for zone device folios, to check if a folio is >> device private and helpers for setting zone de

Re: [RFC 02/11] mm/migrate_device: flags for selecting device private THP pages

On 7/8/25 23:41, David Hildenbrand wrote: > On 06.03.25 05:42, Balbir Singh wrote: >> Add flags to mark zone device migration pages. >> >> MIGRATE_VMA_SELECT_COMPOUND will be used to select THP pages during >> migrate_vma_setup() and MIGRATE_PFN_COMPOUND will make m

Re: [RFC 03/11] mm/thp: zone_device awareness in THP handling code

On 7/9/25 00:10, David Hildenbrand wrote: > On 06.03.25 05:42, Balbir Singh wrote: >> Make THP handling code in the mm subsystem for THP pages >> aware of zone device pages. Although the code is >> designed to be generic when it comes to handling splitting >> of pages, t

Re: [RFC 05/11] mm/memory/fault: Add support for zone device THP fault handling

On 7/9/25 00:40, David Hildenbrand wrote: > On 06.03.25 05:42, Balbir Singh wrote: >> When the CPU touches a zone device THP entry, the data needs to >> be migrated back to the CPU, call migrate_to_ram() on these pages >> via do_huge_pmd_device_private() fault handling helper

Re: [RFC 07/11] mm/memremap: Add folio_split support

On 7/9/25 00:31, David Hildenbrand wrote: > On 06.03.25 05:42, Balbir Singh wrote: >> When a zone device page is split (via huge pmd folio split). The >> driver callback for folio_split is invoked to let the device driver >> know that the folio size has been split into a sma

Re: [RFC 00/11] THP support for zone device pages

On 7/5/25 02:17, Zi Yan wrote: > On 4 Jul 2025, at 9:52, Francois Dugast wrote: > >> Hi, >> >> On Fri, Mar 07, 2025 at 10:20:30AM +1100, Balbir Singh wrote: >>> On 3/7/25 10:08, Matthew Brost wrote: >>>> On Thu, Mar 06, 2025 at 03:42:28PM +1100, Balb

Re: drm/ttm/memcg/lru: enable memcg tracking for ttm and amdgpu driver

d need to think about their overall memory utilization or discover it with ability to overcommit via swap as needed. How does dmem fit into the picture? Is the cgroup integration designed to overcommit or limit dmem/both? Is the programmer expected to know how much dmem the program will need? May be this was answered, but I missed it. Balbir Singh