* [v1 00/12] THP support for zone device page migration
@ 2025-07-03 22:27 Balbir Singh
2025-07-03 22:27 ` [v1 01/12] mm/zone_device: support large zone device private folios Balbir Singh
` (12 more replies)
0 siblings, 13 replies; 15+ messages in thread
From: Balbir Singh @ 2025-07-03 22:27 UTC (permalink / raw)
To: linux-mm
Cc: akpm, linux-kernel, Balbir Singh, Karol Herbst, Lyude Paul,
Danilo Krummrich, David Airlie, Simona Vetter,
Jérôme Glisse, Shuah Khan, David Hildenbrand,
Barry Song, Baolin Wang, Ryan Roberts, Matthew Wilcox, Peter Xu,
Zi Yan, Kefeng Wang, Jane Chu, Alistair Popple, Donet Tom
This patch series adds support for THP migration of zone device pages.
To do so, the patches implement support for folio zone device pages
by adding support for setting up larger order pages.
These patches build on the earlier posts by Ralph Campbell [1]
Two new flags are added in vma_migration to select and mark compound pages.
migrate_vma_setup(), migrate_vma_pages() and migrate_vma_finalize()
support migration of these pages when MIGRATE_VMA_SELECT_COMPOUND
is passed in as arguments.
The series also adds zone device awareness to (m)THP pages along
with fault handling of large zone device private pages. page vma walk
and the rmap code is also zone device aware. Support has also been
added for folios that might need to be split in the middle
of migration (when the src and dst do not agree on
MIGRATE_PFN_COMPOUND), that occurs when src side of the migration can
migrate large pages, but the destination has not been able to allocate
large pages. The code supported and used folio_split() when migrating
THP pages, this is used when MIGRATE_VMA_SELECT_COMPOUND is not passed
as an argument to migrate_vma_setup().
The test infrastructure lib/test_hmm.c has been enhanced to support THP
migration. A new ioctl to emulate failure of large page allocations has
been added to test the folio split code path. hmm-tests.c has new test
cases for huge page migration and to test the folio split path. A new
throughput test has been added as well.
The nouveau dmem code has been enhanced to use the new THP migration
capability.
Feedback from the RFC [2]:
It was advised that prep_compound_page() not be exposed just for the purposes
of testing (test driver lib/test_hmm.c). Work arounds of copy and split the
folios did not work due to lock order dependency in the callback for
split folio.
mTHP support:
The patches hard code, HPAGE_PMD_NR in a few places, but the code has
been kept generic to support various order sizes. With additional
refactoring of the code support of different order sizes should be
possible.
The future plan is to post enhancements to support mTHP with a rough
design as follows:
1. Add the notion of allowable thp orders to the HMM based test driver
2. For non PMD based THP paths in migrate_device.c, check to see if
a suitable order is found and supported by the driver
3. Iterate across orders to check the highest supported order for migration
4. Migrate and finalize
The mTHP patches can be built on top of this series, the key design elements
that need to be worked out are infrastructure and driver support for multiple
ordered pages and their migration.
References:
[1] https://lore.kernel.org/linux-mm/20201106005147.20113-1-rcampbell@nvidia.com/
[2] https://lore.kernel.org/linux-mm/20250306044239.3874247-3-balbirs@nvidia.com/T/
These patches are built on top of mm-unstable
Cc: Karol Herbst <kherbst@redhat.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: David Airlie <airlied@gmail.com>
Cc: Simona Vetter <simona@ffwll.ch>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Donet Tom <donettom@linux.ibm.com>
Changelog v1:
- Changes from RFC [2], include support for handling fault_folio and using
trylock in the fault path
- A new test case has been added to measure the throughput improvement
- General refactoring of code to keep up with the changes in mm
- New split folio callback when the entire split is complete/done. The
callback is used to know when the head order needs to be reset.
Testing:
- Testing was done with ZONE_DEVICE private pages on an x86 VM
- Throughput showed upto 5x improvement with THP migration, system to device
migration is slower due to the mirroring of data (see buffer->mirror)
Balbir Singh (12):
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 handling code
mm/migrate_device: THP migration of zone device pages
mm/memory/fault: Add support for zone device THP fault handling
lib/test_hmm: test cases and support for zone device private THP
mm/memremap: Add folio_split support
mm/thp: add split during migration support
lib/test_hmm: add test case for split pages
selftests/mm/hmm-tests: new tests for zone device THP migration
gpu/drm/nouveau: Add THP migration support
selftests/mm/hmm-tests: New throughput tests including THP
drivers/gpu/drm/nouveau/nouveau_dmem.c | 246 +++++---
drivers/gpu/drm/nouveau/nouveau_svm.c | 6 +-
drivers/gpu/drm/nouveau/nouveau_svm.h | 3 +-
include/linux/huge_mm.h | 18 +-
include/linux/memremap.h | 29 +-
include/linux/migrate.h | 2 +
include/linux/mm.h | 1 +
lib/test_hmm.c | 428 ++++++++++---
lib/test_hmm_uapi.h | 3 +
mm/huge_memory.c | 261 ++++++--
mm/memory.c | 6 +-
mm/memremap.c | 50 +-
mm/migrate.c | 2 +
mm/migrate_device.c | 488 ++++++++++++---
mm/page_alloc.c | 1 +
mm/page_vma_mapped.c | 10 +
mm/pgtable-generic.c | 6 +
mm/rmap.c | 19 +-
tools/testing/selftests/mm/hmm-tests.c | 805 ++++++++++++++++++++++++-
19 files changed, 2072 insertions(+), 312 deletions(-)
--
2.49.0
^ permalink raw reply [flat|nested] 15+ messages in thread
* [v1 01/12] mm/zone_device: support large zone device private folios
2025-07-03 22:27 [v1 00/12] THP support for zone device page migration Balbir Singh
@ 2025-07-03 22:27 ` Balbir Singh
2025-07-03 22:27 ` [v1 02/12] mm/migrate_device: flags for selecting device private THP pages Balbir Singh
` (11 subsequent siblings)
12 siblings, 0 replies; 15+ messages in thread
From: Balbir Singh @ 2025-07-03 22:27 UTC (permalink / raw)
To: linux-mm; +Cc: akpm, linux-kernel, Balbir Singh
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 device data.
When large folios are used, the existing page_free() callback in
pgmap is called when the folio is freed, this is true for both
PAGE_SIZE and higher order pages.
Signed-off-by: Balbir Singh <balbirs@nvidia.com>
---
include/linux/memremap.h | 22 +++++++++++++++++-
mm/memremap.c | 50 +++++++++++++++++++++++++++++-----------
2 files changed, 58 insertions(+), 14 deletions(-)
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 4aa151914eab..11d586dd8ef1 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -169,6 +169,18 @@ static inline bool folio_is_device_private(const struct folio *folio)
return is_device_private_page(&folio->page);
}
+static inline void *folio_zone_device_data(const struct folio *folio)
+{
+ VM_BUG_ON_FOLIO(!folio_is_device_private(folio), folio);
+ return folio->page.zone_device_data;
+}
+
+static inline void folio_set_zone_device_data(struct folio *folio, void *data)
+{
+ VM_BUG_ON_FOLIO(!folio_is_device_private(folio), folio);
+ folio->page.zone_device_data = data;
+}
+
static inline bool is_pci_p2pdma_page(const struct page *page)
{
return IS_ENABLED(CONFIG_PCI_P2PDMA) &&
@@ -199,7 +211,7 @@ static inline bool folio_is_fsdax(const struct folio *folio)
}
#ifdef CONFIG_ZONE_DEVICE
-void zone_device_page_init(struct page *page);
+void init_zone_device_folio(struct folio *folio, unsigned int order);
void *memremap_pages(struct dev_pagemap *pgmap, int nid);
void memunmap_pages(struct dev_pagemap *pgmap);
void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
@@ -209,6 +221,14 @@ struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn);
unsigned long memremap_compat_align(void);
+
+static inline void zone_device_page_init(struct page *page)
+{
+ struct folio *folio = page_folio(page);
+
+ init_zone_device_folio(folio, 0);
+}
+
#else
static inline void *devm_memremap_pages(struct device *dev,
struct dev_pagemap *pgmap)
diff --git a/mm/memremap.c b/mm/memremap.c
index b0ce0d8254bd..4085a3893e64 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -427,20 +427,21 @@ EXPORT_SYMBOL_GPL(get_dev_pagemap);
void free_zone_device_folio(struct folio *folio)
{
struct dev_pagemap *pgmap = folio->pgmap;
+ unsigned int nr = folio_nr_pages(folio);
+ int i;
+ bool anon = folio_test_anon(folio);
+ struct page *page = folio_page(folio, 0);
if (WARN_ON_ONCE(!pgmap))
return;
mem_cgroup_uncharge(folio);
- /*
- * Note: we don't expect anonymous compound pages yet. Once supported
- * and we could PTE-map them similar to THP, we'd have to clear
- * PG_anon_exclusive on all tail pages.
- */
- if (folio_test_anon(folio)) {
- VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
- __ClearPageAnonExclusive(folio_page(folio, 0));
+ WARN_ON_ONCE(folio_test_large(folio) && !anon);
+
+ for (i = 0; i < nr; i++) {
+ if (anon)
+ __ClearPageAnonExclusive(folio_page(folio, i));
}
/*
@@ -464,10 +465,19 @@ void free_zone_device_folio(struct folio *folio)
switch (pgmap->type) {
case MEMORY_DEVICE_PRIVATE:
+ if (folio_test_large(folio)) {
+ folio_unqueue_deferred_split(folio);
+
+ percpu_ref_put_many(&folio->pgmap->ref, nr - 1);
+ }
+ pgmap->ops->page_free(page);
+ put_dev_pagemap(pgmap);
+ page->mapping = NULL;
+ break;
case MEMORY_DEVICE_COHERENT:
if (WARN_ON_ONCE(!pgmap->ops || !pgmap->ops->page_free))
break;
- pgmap->ops->page_free(folio_page(folio, 0));
+ pgmap->ops->page_free(page);
put_dev_pagemap(pgmap);
break;
@@ -491,14 +501,28 @@ void free_zone_device_folio(struct folio *folio)
}
}
-void zone_device_page_init(struct page *page)
+void init_zone_device_folio(struct folio *folio, unsigned int order)
{
+ struct page *page = folio_page(folio, 0);
+
+ VM_BUG_ON(order > MAX_ORDER_NR_PAGES);
+
+ WARN_ON_ONCE(order && order != HPAGE_PMD_ORDER);
+
/*
* Drivers shouldn't be allocating pages after calling
* memunmap_pages().
*/
- WARN_ON_ONCE(!percpu_ref_tryget_live(&page_pgmap(page)->ref));
- set_page_count(page, 1);
+ WARN_ON_ONCE(!percpu_ref_tryget_many(&page_pgmap(page)->ref, 1 << order));
+ folio_set_count(folio, 1);
lock_page(page);
+
+ /*
+ * Only PMD level migration is supported for THP migration
+ */
+ if (order > 1) {
+ prep_compound_page(page, order);
+ folio_set_large_rmappable(folio);
+ }
}
-EXPORT_SYMBOL_GPL(zone_device_page_init);
+EXPORT_SYMBOL_GPL(init_zone_device_folio);
--
2.49.0
^ permalink raw reply related [flat|nested] 15+ messages in thread
* [v1 02/12] mm/migrate_device: flags for selecting device private THP pages
2025-07-03 22:27 [v1 00/12] THP support for zone device page migration Balbir Singh
2025-07-03 22:27 ` [v1 01/12] mm/zone_device: support large zone device private folios Balbir Singh
@ 2025-07-03 22:27 ` Balbir Singh
2025-07-03 22:27 ` [v1 03/12] mm/thp: zone_device awareness in THP handling code Balbir Singh
` (10 subsequent siblings)
12 siblings, 0 replies; 15+ messages in thread
From: Balbir Singh @ 2025-07-03 22:27 UTC (permalink / raw)
To: linux-mm; +Cc: akpm, linux-kernel, Balbir Singh
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 <balbirs@nvidia.com>
---
include/linux/migrate.h | 2 ++
1 file changed, 2 insertions(+)
diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index aaa2114498d6..1661e2d5479a 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -167,6 +167,7 @@ static inline int migrate_misplaced_folio(struct folio *folio, int node)
#define MIGRATE_PFN_VALID (1UL << 0)
#define MIGRATE_PFN_MIGRATE (1UL << 1)
#define MIGRATE_PFN_WRITE (1UL << 3)
+#define MIGRATE_PFN_COMPOUND (1UL << 4)
#define MIGRATE_PFN_SHIFT 6
static inline struct page *migrate_pfn_to_page(unsigned long mpfn)
@@ -185,6 +186,7 @@ enum migrate_vma_direction {
MIGRATE_VMA_SELECT_SYSTEM = 1 << 0,
MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1,
MIGRATE_VMA_SELECT_DEVICE_COHERENT = 1 << 2,
+ MIGRATE_VMA_SELECT_COMPOUND = 1 << 3,
};
struct migrate_vma {
--
2.49.0
^ permalink raw reply related [flat|nested] 15+ messages in thread
* [v1 03/12] mm/thp: zone_device awareness in THP handling code
2025-07-03 22:27 [v1 00/12] THP support for zone device page migration Balbir Singh
2025-07-03 22:27 ` [v1 01/12] mm/zone_device: support large zone device private folios Balbir Singh
2025-07-03 22:27 ` [v1 02/12] mm/migrate_device: flags for selecting device private THP pages Balbir Singh
@ 2025-07-03 22:27 ` Balbir Singh
2025-07-03 22:27 ` [v1 04/12] mm/migrate_device: THP migration of zone device pages Balbir Singh
` (9 subsequent siblings)
12 siblings, 0 replies; 15+ messages in thread
From: Balbir Singh @ 2025-07-03 22:27 UTC (permalink / raw)
To: linux-mm; +Cc: akpm, linux-kernel, Balbir Singh
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, the code is designed to work for THP page sizes
corresponding to HPAGE_PMD_NR.
Modify page_vma_mapped_walk() to return true when a zone
device huge entry is present, enabling try_to_migrate()
and other code migration paths to appropriately process the
entry
pmd_pfn() does not work well with zone device entries, use
pfn_pmd_entry_to_swap() for checking and comparison as for
zone device entries.
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 <balbirs@nvidia.com>
---
mm/huge_memory.c | 153 +++++++++++++++++++++++++++++++------------
mm/migrate.c | 2 +
mm/page_vma_mapped.c | 10 +++
mm/pgtable-generic.c | 6 ++
mm/rmap.c | 19 +++++-
5 files changed, 146 insertions(+), 44 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index ce130225a8e5..e6e390d0308f 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1711,7 +1711,8 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
if (unlikely(is_swap_pmd(pmd))) {
swp_entry_t entry = pmd_to_swp_entry(pmd);
- VM_BUG_ON(!is_pmd_migration_entry(pmd));
+ VM_BUG_ON(!is_pmd_migration_entry(pmd) &&
+ !is_device_private_entry(entry));
if (!is_readable_migration_entry(entry)) {
entry = make_readable_migration_entry(
swp_offset(entry));
@@ -2222,10 +2223,17 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
} else if (thp_migration_supported()) {
swp_entry_t entry;
- VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
entry = pmd_to_swp_entry(orig_pmd);
folio = pfn_swap_entry_folio(entry);
flush_needed = 0;
+
+ VM_BUG_ON(!is_pmd_migration_entry(*pmd) &&
+ !folio_is_device_private(folio));
+
+ if (folio_is_device_private(folio)) {
+ folio_remove_rmap_pmd(folio, folio_page(folio, 0), vma);
+ WARN_ON_ONCE(folio_mapcount(folio) < 0);
+ }
} else
WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
@@ -2247,6 +2255,15 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
folio_mark_accessed(folio);
}
+ /*
+ * Do a folio put on zone device private pages after
+ * changes to mm_counter, because the folio_put() will
+ * clean folio->mapping and the folio_test_anon() check
+ * will not be usable.
+ */
+ if (folio_is_device_private(folio))
+ folio_put(folio);
+
spin_unlock(ptl);
if (flush_needed)
tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE);
@@ -2375,7 +2392,8 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
struct folio *folio = pfn_swap_entry_folio(entry);
pmd_t newpmd;
- VM_BUG_ON(!is_pmd_migration_entry(*pmd));
+ VM_BUG_ON(!is_pmd_migration_entry(*pmd) &&
+ !folio_is_device_private(folio));
if (is_writable_migration_entry(entry)) {
/*
* A protection check is difficult so
@@ -2388,9 +2406,11 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
newpmd = swp_entry_to_pmd(entry);
if (pmd_swp_soft_dirty(*pmd))
newpmd = pmd_swp_mksoft_dirty(newpmd);
- } else {
+ } else if (is_writable_device_private_entry(entry)) {
+ newpmd = swp_entry_to_pmd(entry);
+ entry = make_device_exclusive_entry(swp_offset(entry));
+ } else
newpmd = *pmd;
- }
if (uffd_wp)
newpmd = pmd_swp_mkuffd_wp(newpmd);
@@ -2842,16 +2862,20 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
struct page *page;
pgtable_t pgtable;
pmd_t old_pmd, _pmd;
- bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false;
- bool anon_exclusive = false, dirty = false;
+ bool young, write, soft_dirty, uffd_wp = false;
+ bool anon_exclusive = false, dirty = false, present = false;
unsigned long addr;
pte_t *pte;
int i;
+ swp_entry_t swp_entry;
VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
- VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd));
+
+ VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
+ && !(is_swap_pmd(*pmd) &&
+ is_device_private_entry(pmd_to_swp_entry(*pmd))));
count_vm_event(THP_SPLIT_PMD);
@@ -2899,20 +2923,25 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
return __split_huge_zero_page_pmd(vma, haddr, pmd);
}
- pmd_migration = is_pmd_migration_entry(*pmd);
- if (unlikely(pmd_migration)) {
- swp_entry_t entry;
+ present = pmd_present(*pmd);
+ if (unlikely(!present)) {
+ swp_entry = pmd_to_swp_entry(*pmd);
old_pmd = *pmd;
- entry = pmd_to_swp_entry(old_pmd);
- page = pfn_swap_entry_to_page(entry);
- write = is_writable_migration_entry(entry);
+
+ folio = pfn_swap_entry_folio(swp_entry);
+ VM_BUG_ON(!is_migration_entry(swp_entry) &&
+ !is_device_private_entry(swp_entry));
+ page = pfn_swap_entry_to_page(swp_entry);
+ write = is_writable_migration_entry(swp_entry);
+
if (PageAnon(page))
- anon_exclusive = is_readable_exclusive_migration_entry(entry);
- young = is_migration_entry_young(entry);
- dirty = is_migration_entry_dirty(entry);
+ anon_exclusive =
+ is_readable_exclusive_migration_entry(swp_entry);
soft_dirty = pmd_swp_soft_dirty(old_pmd);
uffd_wp = pmd_swp_uffd_wp(old_pmd);
+ young = is_migration_entry_young(swp_entry);
+ dirty = is_migration_entry_dirty(swp_entry);
} else {
/*
* Up to this point the pmd is present and huge and userland has
@@ -2996,30 +3025,45 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
* Note that NUMA hinting access restrictions are not transferred to
* avoid any possibility of altering permissions across VMAs.
*/
- if (freeze || pmd_migration) {
+ if (freeze || !present) {
for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
pte_t entry;
- swp_entry_t swp_entry;
-
- if (write)
- swp_entry = make_writable_migration_entry(
- page_to_pfn(page + i));
- else if (anon_exclusive)
- swp_entry = make_readable_exclusive_migration_entry(
- page_to_pfn(page + i));
- else
- swp_entry = make_readable_migration_entry(
- page_to_pfn(page + i));
- if (young)
- swp_entry = make_migration_entry_young(swp_entry);
- if (dirty)
- swp_entry = make_migration_entry_dirty(swp_entry);
- entry = swp_entry_to_pte(swp_entry);
- if (soft_dirty)
- entry = pte_swp_mksoft_dirty(entry);
- if (uffd_wp)
- entry = pte_swp_mkuffd_wp(entry);
-
+ if (freeze || is_migration_entry(swp_entry)) {
+ if (write)
+ swp_entry = make_writable_migration_entry(
+ page_to_pfn(page + i));
+ else if (anon_exclusive)
+ swp_entry = make_readable_exclusive_migration_entry(
+ page_to_pfn(page + i));
+ else
+ swp_entry = make_readable_migration_entry(
+ page_to_pfn(page + i));
+ if (young)
+ swp_entry = make_migration_entry_young(swp_entry);
+ if (dirty)
+ swp_entry = make_migration_entry_dirty(swp_entry);
+ entry = swp_entry_to_pte(swp_entry);
+ if (soft_dirty)
+ entry = pte_swp_mksoft_dirty(entry);
+ if (uffd_wp)
+ entry = pte_swp_mkuffd_wp(entry);
+ } else {
+ VM_BUG_ON(!is_device_private_entry(swp_entry));
+ if (write)
+ swp_entry = make_writable_device_private_entry(
+ page_to_pfn(page + i));
+ else if (anon_exclusive)
+ swp_entry = make_device_exclusive_entry(
+ page_to_pfn(page + i));
+ else
+ swp_entry = make_readable_device_private_entry(
+ page_to_pfn(page + i));
+ entry = swp_entry_to_pte(swp_entry);
+ if (soft_dirty)
+ entry = pte_swp_mksoft_dirty(entry);
+ if (uffd_wp)
+ entry = pte_swp_mkuffd_wp(entry);
+ }
VM_WARN_ON(!pte_none(ptep_get(pte + i)));
set_pte_at(mm, addr, pte + i, entry);
}
@@ -3046,7 +3090,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
}
pte_unmap(pte);
- if (!pmd_migration)
+ if (present)
folio_remove_rmap_pmd(folio, page, vma);
if (freeze)
put_page(page);
@@ -3058,8 +3102,11 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
void split_huge_pmd_locked(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmd, bool freeze)
{
+
VM_WARN_ON_ONCE(!IS_ALIGNED(address, HPAGE_PMD_SIZE));
- if (pmd_trans_huge(*pmd) || is_pmd_migration_entry(*pmd))
+ if (pmd_trans_huge(*pmd) || is_pmd_migration_entry(*pmd) ||
+ (is_swap_pmd(*pmd) &&
+ is_device_private_entry(pmd_to_swp_entry(*pmd))))
__split_huge_pmd_locked(vma, pmd, address, freeze);
}
@@ -3238,6 +3285,9 @@ static void lru_add_split_folio(struct folio *folio, struct folio *new_folio,
VM_BUG_ON_FOLIO(folio_test_lru(new_folio), folio);
lockdep_assert_held(&lruvec->lru_lock);
+ if (folio_is_device_private(folio))
+ return;
+
if (list) {
/* page reclaim is reclaiming a huge page */
VM_WARN_ON(folio_test_lru(folio));
@@ -3252,6 +3302,7 @@ static void lru_add_split_folio(struct folio *folio, struct folio *new_folio,
list_add_tail(&new_folio->lru, &folio->lru);
folio_set_lru(new_folio);
}
+
}
/* Racy check whether the huge page can be split */
@@ -3543,6 +3594,10 @@ static int __split_unmapped_folio(struct folio *folio, int new_order,
((mapping || swap_cache) ?
folio_nr_pages(release) : 0));
+ if (folio_is_device_private(release))
+ percpu_ref_get_many(&release->pgmap->ref,
+ (1 << new_order) - 1);
+
lru_add_split_folio(origin_folio, release, lruvec,
list);
@@ -4596,7 +4651,10 @@ int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
return 0;
flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
- pmdval = pmdp_invalidate(vma, address, pvmw->pmd);
+ if (!folio_is_device_private(folio))
+ pmdval = pmdp_invalidate(vma, address, pvmw->pmd);
+ else
+ pmdval = pmdp_huge_clear_flush(vma, address, pvmw->pmd);
/* See folio_try_share_anon_rmap_pmd(): invalidate PMD first. */
anon_exclusive = folio_test_anon(folio) && PageAnonExclusive(page);
@@ -4646,6 +4704,17 @@ void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
entry = pmd_to_swp_entry(*pvmw->pmd);
folio_get(folio);
pmde = folio_mk_pmd(folio, READ_ONCE(vma->vm_page_prot));
+
+ if (unlikely(folio_is_device_private(folio))) {
+ if (pmd_write(pmde))
+ entry = make_writable_device_private_entry(
+ page_to_pfn(new));
+ else
+ entry = make_readable_device_private_entry(
+ page_to_pfn(new));
+ pmde = swp_entry_to_pmd(entry);
+ }
+
if (pmd_swp_soft_dirty(*pvmw->pmd))
pmde = pmd_mksoft_dirty(pmde);
if (is_writable_migration_entry(entry))
diff --git a/mm/migrate.c b/mm/migrate.c
index 767f503f0875..0b6ecf559b22 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -200,6 +200,8 @@ static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw,
if (PageCompound(page))
return false;
+ if (folio_is_device_private(folio))
+ return false;
VM_BUG_ON_PAGE(!PageAnon(page), page);
VM_BUG_ON_PAGE(!PageLocked(page), page);
VM_BUG_ON_PAGE(pte_present(ptep_get(pvmw->pte)), page);
diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index e981a1a292d2..ff8254e52de5 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -277,6 +277,16 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
* cannot return prematurely, while zap_huge_pmd() has
* cleared *pmd but not decremented compound_mapcount().
*/
+ swp_entry_t entry;
+
+ if (!thp_migration_supported())
+ return not_found(pvmw);
+ entry = pmd_to_swp_entry(pmde);
+ if (is_device_private_entry(entry)) {
+ pvmw->ptl = pmd_lock(mm, pvmw->pmd);
+ return true;
+ }
+
if ((pvmw->flags & PVMW_SYNC) &&
thp_vma_suitable_order(vma, pvmw->address,
PMD_ORDER) &&
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index 567e2d084071..604e8206a2ec 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -292,6 +292,12 @@ pte_t *___pte_offset_map(pmd_t *pmd, unsigned long addr, pmd_t *pmdvalp)
*pmdvalp = pmdval;
if (unlikely(pmd_none(pmdval) || is_pmd_migration_entry(pmdval)))
goto nomap;
+ if (is_swap_pmd(pmdval)) {
+ swp_entry_t entry = pmd_to_swp_entry(pmdval);
+
+ if (is_device_private_entry(entry))
+ goto nomap;
+ }
if (unlikely(pmd_trans_huge(pmdval)))
goto nomap;
if (unlikely(pmd_bad(pmdval))) {
diff --git a/mm/rmap.c b/mm/rmap.c
index bd83724d14b6..da1e5b03e1fe 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -2336,8 +2336,23 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
break;
}
#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
- subpage = folio_page(folio,
- pmd_pfn(*pvmw.pmd) - folio_pfn(folio));
+ /*
+ * Zone device private folios do not work well with
+ * pmd_pfn() on some architectures due to pte
+ * inversion.
+ */
+ if (folio_is_device_private(folio)) {
+ swp_entry_t entry = pmd_to_swp_entry(*pvmw.pmd);
+ unsigned long pfn = swp_offset_pfn(entry);
+
+ subpage = folio_page(folio, pfn
+ - folio_pfn(folio));
+ } else {
+ subpage = folio_page(folio,
+ pmd_pfn(*pvmw.pmd)
+ - folio_pfn(folio));
+ }
+
VM_BUG_ON_FOLIO(folio_test_hugetlb(folio) ||
!folio_test_pmd_mappable(folio), folio);
--
2.49.0
^ permalink raw reply related [flat|nested] 15+ messages in thread
* [v1 04/12] mm/migrate_device: THP migration of zone device pages
2025-07-03 22:27 [v1 00/12] THP support for zone device page migration Balbir Singh
` (2 preceding siblings ...)
2025-07-03 22:27 ` [v1 03/12] mm/thp: zone_device awareness in THP handling code Balbir Singh
@ 2025-07-03 22:27 ` Balbir Singh
2025-07-03 22:27 ` [v1 05/12] mm/memory/fault: add support for zone device THP fault handling Balbir Singh
` (8 subsequent siblings)
12 siblings, 0 replies; 15+ messages in thread
From: Balbir Singh @ 2025-07-03 22:27 UTC (permalink / raw)
To: linux-mm; +Cc: akpm, linux-kernel, Balbir Singh
migrate_device code paths go through the collect, setup
and finalize phases of migration. Support for MIGRATE_PFN_COMPOUND
was added earlier in the series to mark THP pages as
MIGRATE_PFN_COMPOUND.
The entries in src and dst arrays passed to these functions still
remain at a PAGE_SIZE granularity. When a compound page is passed,
the first entry has the PFN along with MIGRATE_PFN_COMPOUND
and other flags set (MIGRATE_PFN_MIGRATE, MIGRATE_PFN_VALID), the
remaining entries (HPAGE_PMD_NR - 1) are filled with 0's. This
representation allows for the compound page to be split into smaller
page sizes.
migrate_vma_collect_hole(), migrate_vma_collect_pmd() are now THP
page aware. Two new helper functions migrate_vma_collect_huge_pmd()
and migrate_vma_insert_huge_pmd_page() have been added.
migrate_vma_collect_huge_pmd() can collect THP pages, but if for
some reason this fails, there 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 <balbirs@nvidia.com>
---
mm/migrate_device.c | 437 +++++++++++++++++++++++++++++++++++++-------
1 file changed, 376 insertions(+), 61 deletions(-)
diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index e05e14d6eacd..41d0bd787969 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -14,6 +14,7 @@
#include <linux/pagewalk.h>
#include <linux/rmap.h>
#include <linux/swapops.h>
+#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include "internal.h"
@@ -44,6 +45,23 @@ static int migrate_vma_collect_hole(unsigned long start,
if (!vma_is_anonymous(walk->vma))
return migrate_vma_collect_skip(start, end, walk);
+ if (thp_migration_supported() &&
+ (migrate->flags & MIGRATE_VMA_SELECT_COMPOUND) &&
+ (IS_ALIGNED(start, HPAGE_PMD_SIZE) &&
+ IS_ALIGNED(end, HPAGE_PMD_SIZE))) {
+ migrate->src[migrate->npages] = MIGRATE_PFN_MIGRATE |
+ MIGRATE_PFN_COMPOUND;
+ migrate->dst[migrate->npages] = 0;
+ migrate->npages++;
+ migrate->cpages++;
+
+ /*
+ * Collect the remaining entries as holes, in case we
+ * need to split later
+ */
+ return migrate_vma_collect_skip(start + PAGE_SIZE, end, walk);
+ }
+
for (addr = start; addr < end; addr += PAGE_SIZE) {
migrate->src[migrate->npages] = MIGRATE_PFN_MIGRATE;
migrate->dst[migrate->npages] = 0;
@@ -54,57 +72,148 @@ static int migrate_vma_collect_hole(unsigned long start,
return 0;
}
-static int migrate_vma_collect_pmd(pmd_t *pmdp,
- unsigned long start,
- unsigned long end,
- struct mm_walk *walk)
+/**
+ * migrate_vma_collect_huge_pmd - collect THP pages without splitting the
+ * folio for device private pages.
+ * @pmdp: pointer to pmd entry
+ * @start: start address of the range for migration
+ * @end: end address of the range for migration
+ * @walk: mm_walk callback structure
+ *
+ * Collect the huge pmd entry at @pmdp for migration and set the
+ * MIGRATE_PFN_COMPOUND flag in the migrate src entry to indicate that
+ * migration will occur at HPAGE_PMD granularity
+ */
+static int migrate_vma_collect_huge_pmd(pmd_t *pmdp, unsigned long start,
+ unsigned long end, struct mm_walk *walk,
+ struct folio *fault_folio)
{
+ struct mm_struct *mm = walk->mm;
+ struct folio *folio;
struct migrate_vma *migrate = walk->private;
- struct folio *fault_folio = migrate->fault_page ?
- page_folio(migrate->fault_page) : NULL;
- struct vm_area_struct *vma = walk->vma;
- struct mm_struct *mm = vma->vm_mm;
- unsigned long addr = start, unmapped = 0;
spinlock_t *ptl;
- pte_t *ptep;
+ swp_entry_t entry;
+ int ret;
+ unsigned long write = 0;
-again:
- if (pmd_none(*pmdp))
+ ptl = pmd_lock(mm, pmdp);
+ if (pmd_none(*pmdp)) {
+ spin_unlock(ptl);
return migrate_vma_collect_hole(start, end, -1, walk);
+ }
if (pmd_trans_huge(*pmdp)) {
- struct folio *folio;
-
- ptl = pmd_lock(mm, pmdp);
- if (unlikely(!pmd_trans_huge(*pmdp))) {
+ if (!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM)) {
spin_unlock(ptl);
- goto again;
+ return migrate_vma_collect_skip(start, end, walk);
}
folio = pmd_folio(*pmdp);
if (is_huge_zero_folio(folio)) {
spin_unlock(ptl);
- split_huge_pmd(vma, pmdp, addr);
- } else {
- int ret;
+ return migrate_vma_collect_hole(start, end, -1, walk);
+ }
+ if (pmd_write(*pmdp))
+ write = MIGRATE_PFN_WRITE;
+ } else if (!pmd_present(*pmdp)) {
+ entry = pmd_to_swp_entry(*pmdp);
+ folio = pfn_swap_entry_folio(entry);
+
+ if (!is_device_private_entry(entry) ||
+ !(migrate->flags & MIGRATE_VMA_SELECT_DEVICE_PRIVATE) ||
+ (folio->pgmap->owner != migrate->pgmap_owner)) {
+ spin_unlock(ptl);
+ return migrate_vma_collect_skip(start, end, walk);
+ }
- folio_get(folio);
+ if (is_migration_entry(entry)) {
+ migration_entry_wait_on_locked(entry, ptl);
spin_unlock(ptl);
- /* FIXME: we don't expect THP for fault_folio */
- if (WARN_ON_ONCE(fault_folio == folio))
- return migrate_vma_collect_skip(start, end,
- walk);
- if (unlikely(!folio_trylock(folio)))
- return migrate_vma_collect_skip(start, end,
- walk);
- ret = split_folio(folio);
- if (fault_folio != folio)
- folio_unlock(folio);
- folio_put(folio);
- if (ret)
- return migrate_vma_collect_skip(start, end,
- walk);
+ return -EAGAIN;
}
+
+ if (is_writable_device_private_entry(entry))
+ write = MIGRATE_PFN_WRITE;
+ } else {
+ spin_unlock(ptl);
+ return -EAGAIN;
+ }
+
+ folio_get(folio);
+ if (folio != fault_folio && unlikely(!folio_trylock(folio))) {
+ spin_unlock(ptl);
+ folio_put(folio);
+ return migrate_vma_collect_skip(start, end, walk);
+ }
+
+ if (thp_migration_supported() &&
+ (migrate->flags & MIGRATE_VMA_SELECT_COMPOUND) &&
+ (IS_ALIGNED(start, HPAGE_PMD_SIZE) &&
+ IS_ALIGNED(end, HPAGE_PMD_SIZE))) {
+
+ struct page_vma_mapped_walk pvmw = {
+ .ptl = ptl,
+ .address = start,
+ .pmd = pmdp,
+ .vma = walk->vma,
+ };
+
+ unsigned long pfn = page_to_pfn(folio_page(folio, 0));
+
+ migrate->src[migrate->npages] = migrate_pfn(pfn) | write
+ | MIGRATE_PFN_MIGRATE
+ | MIGRATE_PFN_COMPOUND;
+ migrate->dst[migrate->npages++] = 0;
+ migrate->cpages++;
+ ret = set_pmd_migration_entry(&pvmw, folio_page(folio, 0));
+ if (ret) {
+ migrate->npages--;
+ migrate->cpages--;
+ migrate->src[migrate->npages] = 0;
+ migrate->dst[migrate->npages] = 0;
+ goto fallback;
+ }
+ migrate_vma_collect_skip(start + PAGE_SIZE, end, walk);
+ spin_unlock(ptl);
+ return 0;
+ }
+
+fallback:
+ spin_unlock(ptl);
+ ret = split_folio(folio);
+ if (fault_folio != folio)
+ folio_unlock(folio);
+ folio_put(folio);
+ if (ret)
+ return migrate_vma_collect_skip(start, end, walk);
+ if (pmd_none(pmdp_get_lockless(pmdp)))
+ return migrate_vma_collect_hole(start, end, -1, walk);
+
+ return -ENOENT;
+}
+
+static int migrate_vma_collect_pmd(pmd_t *pmdp,
+ unsigned long start,
+ unsigned long end,
+ struct mm_walk *walk)
+{
+ struct migrate_vma *migrate = walk->private;
+ struct vm_area_struct *vma = walk->vma;
+ struct mm_struct *mm = vma->vm_mm;
+ unsigned long addr = start, unmapped = 0;
+ spinlock_t *ptl;
+ struct folio *fault_folio = migrate->fault_page ?
+ page_folio(migrate->fault_page) : NULL;
+ pte_t *ptep;
+
+again:
+ if (pmd_trans_huge(*pmdp) || !pmd_present(*pmdp)) {
+ int ret = migrate_vma_collect_huge_pmd(pmdp, start, end, walk, fault_folio);
+
+ if (ret == -EAGAIN)
+ goto again;
+ if (ret == 0)
+ return 0;
}
ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl);
@@ -175,8 +284,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
mpfn |= pte_write(pte) ? MIGRATE_PFN_WRITE : 0;
}
- /* FIXME support THP */
- if (!page || !page->mapping || PageTransCompound(page)) {
+ if (!page || !page->mapping) {
mpfn = 0;
goto next;
}
@@ -347,14 +455,6 @@ static bool migrate_vma_check_page(struct page *page, struct page *fault_page)
*/
int extra = 1 + (page == fault_page);
- /*
- * FIXME support THP (transparent huge page), it is bit more complex to
- * check them than regular pages, because they can be mapped with a pmd
- * or with a pte (split pte mapping).
- */
- if (folio_test_large(folio))
- return false;
-
/* Page from ZONE_DEVICE have one extra reference */
if (folio_is_zone_device(folio))
extra++;
@@ -385,17 +485,24 @@ static unsigned long migrate_device_unmap(unsigned long *src_pfns,
lru_add_drain();
- for (i = 0; i < npages; i++) {
+ for (i = 0; i < npages; ) {
struct page *page = migrate_pfn_to_page(src_pfns[i]);
struct folio *folio;
+ unsigned int nr = 1;
if (!page) {
if (src_pfns[i] & MIGRATE_PFN_MIGRATE)
unmapped++;
- continue;
+ goto next;
}
folio = page_folio(page);
+ nr = folio_nr_pages(folio);
+
+ if (nr > 1)
+ src_pfns[i] |= MIGRATE_PFN_COMPOUND;
+
+
/* ZONE_DEVICE folios are not on LRU */
if (!folio_is_zone_device(folio)) {
if (!folio_test_lru(folio) && allow_drain) {
@@ -407,7 +514,7 @@ static unsigned long migrate_device_unmap(unsigned long *src_pfns,
if (!folio_isolate_lru(folio)) {
src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
restore++;
- continue;
+ goto next;
}
/* Drop the reference we took in collect */
@@ -426,10 +533,12 @@ static unsigned long migrate_device_unmap(unsigned long *src_pfns,
src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
restore++;
- continue;
+ goto next;
}
unmapped++;
+next:
+ i += nr;
}
for (i = 0; i < npages && restore; i++) {
@@ -575,6 +684,146 @@ int migrate_vma_setup(struct migrate_vma *args)
}
EXPORT_SYMBOL(migrate_vma_setup);
+#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
+/**
+ * migrate_vma_insert_huge_pmd_page: Insert a huge folio into @migrate->vma->vm_mm
+ * at @addr. folio is already allocated as a part of the migration process with
+ * large page.
+ *
+ * @folio needs to be initialized and setup after it's allocated. The code bits
+ * here follow closely the code in __do_huge_pmd_anonymous_page(). This API does
+ * not support THP zero pages.
+ *
+ * @migrate: migrate_vma arguments
+ * @addr: address where the folio will be inserted
+ * @folio: folio to be inserted at @addr
+ * @src: src pfn which is being migrated
+ * @pmdp: pointer to the pmd
+ */
+static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate,
+ unsigned long addr,
+ struct page *page,
+ unsigned long *src,
+ pmd_t *pmdp)
+{
+ struct vm_area_struct *vma = migrate->vma;
+ gfp_t gfp = vma_thp_gfp_mask(vma);
+ struct folio *folio = page_folio(page);
+ int ret;
+ spinlock_t *ptl;
+ pgtable_t pgtable;
+ pmd_t entry;
+ bool flush = false;
+ unsigned long i;
+
+ VM_WARN_ON_FOLIO(!folio, folio);
+ VM_WARN_ON_ONCE(!pmd_none(*pmdp) && !is_huge_zero_pmd(*pmdp));
+
+ if (!thp_vma_suitable_order(vma, addr, HPAGE_PMD_ORDER))
+ return -EINVAL;
+
+ ret = anon_vma_prepare(vma);
+ if (ret)
+ return ret;
+
+ folio_set_order(folio, HPAGE_PMD_ORDER);
+ folio_set_large_rmappable(folio);
+
+ if (mem_cgroup_charge(folio, migrate->vma->vm_mm, gfp)) {
+ count_vm_event(THP_FAULT_FALLBACK);
+ count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE);
+ ret = -ENOMEM;
+ goto abort;
+ }
+
+ __folio_mark_uptodate(folio);
+
+ pgtable = pte_alloc_one(vma->vm_mm);
+ if (unlikely(!pgtable))
+ goto abort;
+
+ if (folio_is_device_private(folio)) {
+ swp_entry_t swp_entry;
+
+ if (vma->vm_flags & VM_WRITE)
+ swp_entry = make_writable_device_private_entry(
+ page_to_pfn(page));
+ else
+ swp_entry = make_readable_device_private_entry(
+ page_to_pfn(page));
+ entry = swp_entry_to_pmd(swp_entry);
+ } else {
+ if (folio_is_zone_device(folio) &&
+ !folio_is_device_coherent(folio)) {
+ goto abort;
+ }
+ entry = folio_mk_pmd(folio, vma->vm_page_prot);
+ if (vma->vm_flags & VM_WRITE)
+ entry = pmd_mkwrite(pmd_mkdirty(entry), vma);
+ }
+
+ ptl = pmd_lock(vma->vm_mm, pmdp);
+ ret = check_stable_address_space(vma->vm_mm);
+ if (ret)
+ goto abort;
+
+ /*
+ * Check for userfaultfd but do not deliver the fault. Instead,
+ * just back off.
+ */
+ if (userfaultfd_missing(vma))
+ goto unlock_abort;
+
+ if (!pmd_none(*pmdp)) {
+ if (!is_huge_zero_pmd(*pmdp))
+ goto unlock_abort;
+ flush = true;
+ } else if (!pmd_none(*pmdp))
+ goto unlock_abort;
+
+ add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
+ folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE);
+ if (!folio_is_zone_device(folio))
+ folio_add_lru_vma(folio, vma);
+ folio_get(folio);
+
+ if (flush) {
+ pte_free(vma->vm_mm, pgtable);
+ flush_cache_page(vma, addr, addr + HPAGE_PMD_SIZE);
+ pmdp_invalidate(vma, addr, pmdp);
+ } else {
+ pgtable_trans_huge_deposit(vma->vm_mm, pmdp, pgtable);
+ mm_inc_nr_ptes(vma->vm_mm);
+ }
+ set_pmd_at(vma->vm_mm, addr, pmdp, entry);
+ update_mmu_cache_pmd(vma, addr, pmdp);
+
+ spin_unlock(ptl);
+
+ count_vm_event(THP_FAULT_ALLOC);
+ count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC);
+ count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
+
+ return 0;
+
+unlock_abort:
+ spin_unlock(ptl);
+abort:
+ for (i = 0; i < HPAGE_PMD_NR; i++)
+ src[i] &= ~MIGRATE_PFN_MIGRATE;
+ return 0;
+}
+#else /* !CONFIG_ARCH_ENABLE_THP_MIGRATION */
+static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate,
+ unsigned long addr,
+ struct page *page,
+ unsigned long *src,
+ pmd_t *pmdp)
+{
+ return 0;
+}
+#endif
+
/*
* This code closely matches the code in:
* __handle_mm_fault()
@@ -585,9 +834,10 @@ EXPORT_SYMBOL(migrate_vma_setup);
*/
static void migrate_vma_insert_page(struct migrate_vma *migrate,
unsigned long addr,
- struct page *page,
+ unsigned long *dst,
unsigned long *src)
{
+ struct page *page = migrate_pfn_to_page(*dst);
struct folio *folio = page_folio(page);
struct vm_area_struct *vma = migrate->vma;
struct mm_struct *mm = vma->vm_mm;
@@ -615,8 +865,25 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate,
pmdp = pmd_alloc(mm, pudp, addr);
if (!pmdp)
goto abort;
- if (pmd_trans_huge(*pmdp))
- goto abort;
+
+ if (thp_migration_supported() && (*dst & MIGRATE_PFN_COMPOUND)) {
+ int ret = migrate_vma_insert_huge_pmd_page(migrate, addr, page,
+ src, pmdp);
+ if (ret)
+ goto abort;
+ return;
+ }
+
+ if (!pmd_none(*pmdp)) {
+ if (pmd_trans_huge(*pmdp)) {
+ if (!is_huge_zero_pmd(*pmdp))
+ goto abort;
+ folio_get(pmd_folio(*pmdp));
+ split_huge_pmd(vma, pmdp, addr);
+ } else if (pmd_leaf(*pmdp))
+ goto abort;
+ }
+
if (pte_alloc(mm, pmdp))
goto abort;
if (unlikely(anon_vma_prepare(vma)))
@@ -707,23 +974,24 @@ static void __migrate_device_pages(unsigned long *src_pfns,
unsigned long i;
bool notified = false;
- for (i = 0; i < npages; i++) {
+ for (i = 0; i < npages; ) {
struct page *newpage = migrate_pfn_to_page(dst_pfns[i]);
struct page *page = migrate_pfn_to_page(src_pfns[i]);
struct address_space *mapping;
struct folio *newfolio, *folio;
int r, extra_cnt = 0;
+ unsigned long nr = 1;
if (!newpage) {
src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
- continue;
+ goto next;
}
if (!page) {
unsigned long addr;
if (!(src_pfns[i] & MIGRATE_PFN_MIGRATE))
- continue;
+ goto next;
/*
* The only time there is no vma is when called from
@@ -741,15 +1009,47 @@ static void __migrate_device_pages(unsigned long *src_pfns,
migrate->pgmap_owner);
mmu_notifier_invalidate_range_start(&range);
}
- migrate_vma_insert_page(migrate, addr, newpage,
+
+ if ((src_pfns[i] & MIGRATE_PFN_COMPOUND) &&
+ (!(dst_pfns[i] & MIGRATE_PFN_COMPOUND))) {
+ nr = HPAGE_PMD_NR;
+ src_pfns[i] &= ~MIGRATE_PFN_COMPOUND;
+ src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
+ goto next;
+ }
+
+ migrate_vma_insert_page(migrate, addr, &dst_pfns[i],
&src_pfns[i]);
- continue;
+ goto next;
}
newfolio = page_folio(newpage);
folio = page_folio(page);
mapping = folio_mapping(folio);
+ /*
+ * If THP migration is enabled, check if both src and dst
+ * can migrate large pages
+ */
+ if (thp_migration_supported()) {
+ if ((src_pfns[i] & MIGRATE_PFN_MIGRATE) &&
+ (src_pfns[i] & MIGRATE_PFN_COMPOUND) &&
+ !(dst_pfns[i] & MIGRATE_PFN_COMPOUND)) {
+
+ if (!migrate) {
+ src_pfns[i] &= ~(MIGRATE_PFN_MIGRATE |
+ MIGRATE_PFN_COMPOUND);
+ goto next;
+ }
+ src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
+ } else if ((src_pfns[i] & MIGRATE_PFN_MIGRATE) &&
+ (dst_pfns[i] & MIGRATE_PFN_COMPOUND) &&
+ !(src_pfns[i] & MIGRATE_PFN_COMPOUND)) {
+ src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
+ }
+ }
+
+
if (folio_is_device_private(newfolio) ||
folio_is_device_coherent(newfolio)) {
if (mapping) {
@@ -762,7 +1062,7 @@ static void __migrate_device_pages(unsigned long *src_pfns,
if (!folio_test_anon(folio) ||
!folio_free_swap(folio)) {
src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
- continue;
+ goto next;
}
}
} else if (folio_is_zone_device(newfolio)) {
@@ -770,7 +1070,7 @@ static void __migrate_device_pages(unsigned long *src_pfns,
* Other types of ZONE_DEVICE page are not supported.
*/
src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
- continue;
+ goto next;
}
BUG_ON(folio_test_writeback(folio));
@@ -782,6 +1082,8 @@ static void __migrate_device_pages(unsigned long *src_pfns,
src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
else
folio_migrate_flags(newfolio, folio);
+next:
+ i += nr;
}
if (notified)
@@ -943,10 +1245,23 @@ static unsigned long migrate_device_pfn_lock(unsigned long pfn)
int migrate_device_range(unsigned long *src_pfns, unsigned long start,
unsigned long npages)
{
- unsigned long i, pfn;
+ unsigned long i, j, pfn;
+
+ for (pfn = start, i = 0; i < npages; pfn++, i++) {
+ struct page *page = pfn_to_page(pfn);
+ struct folio *folio = page_folio(page);
+ unsigned int nr = 1;
- for (pfn = start, i = 0; i < npages; pfn++, i++)
src_pfns[i] = migrate_device_pfn_lock(pfn);
+ nr = folio_nr_pages(folio);
+ if (nr > 1) {
+ src_pfns[i] |= MIGRATE_PFN_COMPOUND;
+ for (j = 1; j < nr; j++)
+ src_pfns[i+j] = 0;
+ i += j - 1;
+ pfn += j - 1;
+ }
+ }
migrate_device_unmap(src_pfns, npages, NULL);
--
2.49.0
^ permalink raw reply related [flat|nested] 15+ messages in thread
* [v1 05/12] mm/memory/fault: add support for zone device THP fault handling
2025-07-03 22:27 [v1 00/12] THP support for zone device page migration Balbir Singh
` (3 preceding siblings ...)
2025-07-03 22:27 ` [v1 04/12] mm/migrate_device: THP migration of zone device pages Balbir Singh
@ 2025-07-03 22:27 ` Balbir Singh
2025-07-03 22:27 ` [v1 06/12] lib/test_hmm: test cases and support for zone device private THP Balbir Singh
` (7 subsequent siblings)
12 siblings, 0 replies; 15+ messages in thread
From: Balbir Singh @ 2025-07-03 22:27 UTC (permalink / raw)
To: linux-mm; +Cc: akpm, linux-kernel, Balbir Singh
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 <balbirs@nvidia.com>
---
include/linux/huge_mm.h | 7 +++++++
mm/huge_memory.c | 40 ++++++++++++++++++++++++++++++++++++++++
mm/memory.c | 6 ++++--
3 files changed, 51 insertions(+), 2 deletions(-)
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 4d5bb67dc4ec..65a1bdf29bb9 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -474,6 +474,8 @@ static inline bool folio_test_pmd_mappable(struct folio *folio)
vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf);
+vm_fault_t do_huge_pmd_device_private(struct vm_fault *vmf);
+
extern struct folio *huge_zero_folio;
extern unsigned long huge_zero_pfn;
@@ -627,6 +629,11 @@ static inline vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf)
return 0;
}
+static inline vm_fault_t do_huge_pmd_device_private(struct vm_fault *vmf)
+{
+ return 0;
+}
+
static inline bool is_huge_zero_folio(const struct folio *folio)
{
return false;
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index e6e390d0308f..f29add796931 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1267,6 +1267,46 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf)
}
+vm_fault_t do_huge_pmd_device_private(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
+ vm_fault_t ret = 0;
+ spinlock_t *ptl;
+ swp_entry_t swp_entry;
+ struct page *page;
+
+ if (!thp_vma_suitable_order(vma, haddr, PMD_ORDER))
+ return VM_FAULT_FALLBACK;
+
+ if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
+ vma_end_read(vma);
+ return VM_FAULT_RETRY;
+ }
+
+ ptl = pmd_lock(vma->vm_mm, vmf->pmd);
+ if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd))) {
+ spin_unlock(ptl);
+ return 0;
+ }
+
+ swp_entry = pmd_to_swp_entry(vmf->orig_pmd);
+ page = pfn_swap_entry_to_page(swp_entry);
+ vmf->page = page;
+ vmf->pte = NULL;
+ if (trylock_page(vmf->page)) {
+ get_page(page);
+ spin_unlock(ptl);
+ ret = page_pgmap(page)->ops->migrate_to_ram(vmf);
+ unlock_page(vmf->page);
+ put_page(page);
+ } else {
+ spin_unlock(ptl);
+ }
+
+ return ret;
+}
+
/*
* always: directly stall for all thp allocations
* defer: wake kswapd and fail if not immediately available
diff --git a/mm/memory.c b/mm/memory.c
index 0f9b32a20e5b..c26c421b8325 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -6165,8 +6165,10 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
vmf.orig_pmd = pmdp_get_lockless(vmf.pmd);
if (unlikely(is_swap_pmd(vmf.orig_pmd))) {
- VM_BUG_ON(thp_migration_supported() &&
- !is_pmd_migration_entry(vmf.orig_pmd));
+ if (is_device_private_entry(
+ pmd_to_swp_entry(vmf.orig_pmd)))
+ return do_huge_pmd_device_private(&vmf);
+
if (is_pmd_migration_entry(vmf.orig_pmd))
pmd_migration_entry_wait(mm, vmf.pmd);
return 0;
--
2.49.0
^ permalink raw reply related [flat|nested] 15+ messages in thread
* [v1 06/12] lib/test_hmm: test cases and support for zone device private THP
2025-07-03 22:27 [v1 00/12] THP support for zone device page migration Balbir Singh
` (4 preceding siblings ...)
2025-07-03 22:27 ` [v1 05/12] mm/memory/fault: add support for zone device THP fault handling Balbir Singh
@ 2025-07-03 22:27 ` Balbir Singh
2025-07-03 22:27 ` [v1 07/12] mm/memremap: add folio_split support Balbir Singh
` (6 subsequent siblings)
12 siblings, 0 replies; 15+ messages in thread
From: Balbir Singh @ 2025-07-03 22:27 UTC (permalink / raw)
To: linux-mm; +Cc: akpm, linux-kernel, Balbir Singh
Enhance the hmm test driver (lib/test_hmm) with support for
THP pages.
A new pool of free_folios() has now been added to the dmirror
device, which can be allocated when a request for a THP zone
device private page is made.
Add compound page awareness to the allocation function during
normal migration and fault based migration. These routines also
copy folio_nr_pages() when moving data between system memory
and device memory.
args.src and args.dst used to hold migration entries are now
dynamically allocated (as they need to hold HPAGE_PMD_NR entries
or more).
Split and migrate support will be added in future patches in this
series.
Signed-off-by: Balbir Singh <balbirs@nvidia.com>
---
lib/test_hmm.c | 355 +++++++++++++++++++++++++++++++++++++++----------
1 file changed, 282 insertions(+), 73 deletions(-)
diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index 761725bc713c..95b4276a17fd 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -119,6 +119,7 @@ struct dmirror_device {
unsigned long calloc;
unsigned long cfree;
struct page *free_pages;
+ struct folio *free_folios;
spinlock_t lock; /* protects the above */
};
@@ -492,7 +493,7 @@ static int dmirror_write(struct dmirror *dmirror, struct hmm_dmirror_cmd *cmd)
}
static int dmirror_allocate_chunk(struct dmirror_device *mdevice,
- struct page **ppage)
+ struct page **ppage, bool is_large)
{
struct dmirror_chunk *devmem;
struct resource *res = NULL;
@@ -572,20 +573,45 @@ static int dmirror_allocate_chunk(struct dmirror_device *mdevice,
pfn_first, pfn_last);
spin_lock(&mdevice->lock);
- for (pfn = pfn_first; pfn < pfn_last; pfn++) {
+ for (pfn = pfn_first; pfn < pfn_last; ) {
struct page *page = pfn_to_page(pfn);
+ if (is_large && IS_ALIGNED(pfn, HPAGE_PMD_NR)
+ && (pfn + HPAGE_PMD_NR <= pfn_last)) {
+ page->zone_device_data = mdevice->free_folios;
+ mdevice->free_folios = page_folio(page);
+ pfn += HPAGE_PMD_NR;
+ continue;
+ }
+
page->zone_device_data = mdevice->free_pages;
mdevice->free_pages = page;
+ pfn++;
}
+
+ ret = 0;
if (ppage) {
- *ppage = mdevice->free_pages;
- mdevice->free_pages = (*ppage)->zone_device_data;
- mdevice->calloc++;
+ if (is_large) {
+ if (!mdevice->free_folios) {
+ ret = -ENOMEM;
+ goto err_unlock;
+ }
+ *ppage = folio_page(mdevice->free_folios, 0);
+ mdevice->free_folios = (*ppage)->zone_device_data;
+ mdevice->calloc += HPAGE_PMD_NR;
+ } else if (mdevice->free_pages) {
+ *ppage = mdevice->free_pages;
+ mdevice->free_pages = (*ppage)->zone_device_data;
+ mdevice->calloc++;
+ } else {
+ ret = -ENOMEM;
+ goto err_unlock;
+ }
}
+err_unlock:
spin_unlock(&mdevice->lock);
- return 0;
+ return ret;
err_release:
mutex_unlock(&mdevice->devmem_lock);
@@ -598,10 +624,13 @@ static int dmirror_allocate_chunk(struct dmirror_device *mdevice,
return ret;
}
-static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
+static struct page *dmirror_devmem_alloc_page(struct dmirror *dmirror,
+ bool is_large)
{
struct page *dpage = NULL;
struct page *rpage = NULL;
+ unsigned int order = is_large ? HPAGE_PMD_ORDER : 0;
+ struct dmirror_device *mdevice = dmirror->mdevice;
/*
* For ZONE_DEVICE private type, this is a fake device so we allocate
@@ -610,49 +639,55 @@ static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
* data and ignore rpage.
*/
if (dmirror_is_private_zone(mdevice)) {
- rpage = alloc_page(GFP_HIGHUSER);
+ rpage = folio_page(folio_alloc(GFP_HIGHUSER, order), 0);
if (!rpage)
return NULL;
}
spin_lock(&mdevice->lock);
- if (mdevice->free_pages) {
+ if (is_large && mdevice->free_folios) {
+ dpage = folio_page(mdevice->free_folios, 0);
+ mdevice->free_folios = dpage->zone_device_data;
+ mdevice->calloc += 1 << order;
+ spin_unlock(&mdevice->lock);
+ } else if (!is_large && mdevice->free_pages) {
dpage = mdevice->free_pages;
mdevice->free_pages = dpage->zone_device_data;
mdevice->calloc++;
spin_unlock(&mdevice->lock);
} else {
spin_unlock(&mdevice->lock);
- if (dmirror_allocate_chunk(mdevice, &dpage))
+ if (dmirror_allocate_chunk(mdevice, &dpage, is_large))
goto error;
}
- zone_device_page_init(dpage);
+ init_zone_device_folio(page_folio(dpage), order);
dpage->zone_device_data = rpage;
return dpage;
error:
if (rpage)
- __free_page(rpage);
+ __free_pages(rpage, order);
return NULL;
}
static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
struct dmirror *dmirror)
{
- struct dmirror_device *mdevice = dmirror->mdevice;
const unsigned long *src = args->src;
unsigned long *dst = args->dst;
unsigned long addr;
- for (addr = args->start; addr < args->end; addr += PAGE_SIZE,
- src++, dst++) {
+ for (addr = args->start; addr < args->end; ) {
struct page *spage;
struct page *dpage;
struct page *rpage;
+ bool is_large = *src & MIGRATE_PFN_COMPOUND;
+ int write = (*src & MIGRATE_PFN_WRITE) ? MIGRATE_PFN_WRITE : 0;
+ unsigned long nr = 1;
if (!(*src & MIGRATE_PFN_MIGRATE))
- continue;
+ goto next;
/*
* Note that spage might be NULL which is OK since it is an
@@ -662,17 +697,45 @@ static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
if (WARN(spage && is_zone_device_page(spage),
"page already in device spage pfn: 0x%lx\n",
page_to_pfn(spage)))
+ goto next;
+
+ dpage = dmirror_devmem_alloc_page(dmirror, is_large);
+ if (!dpage) {
+ struct folio *folio;
+ unsigned long i;
+ unsigned long spfn = *src >> MIGRATE_PFN_SHIFT;
+ struct page *src_page;
+
+ if (!is_large)
+ goto next;
+
+ if (!spage && is_large) {
+ nr = HPAGE_PMD_NR;
+ } else {
+ folio = page_folio(spage);
+ nr = folio_nr_pages(folio);
+ }
+
+ for (i = 0; i < nr && addr < args->end; i++) {
+ dpage = dmirror_devmem_alloc_page(dmirror, false);
+ rpage = BACKING_PAGE(dpage);
+ rpage->zone_device_data = dmirror;
+
+ *dst = migrate_pfn(page_to_pfn(dpage)) | write;
+ src_page = pfn_to_page(spfn + i);
+
+ if (spage)
+ copy_highpage(rpage, src_page);
+ else
+ clear_highpage(rpage);
+ src++;
+ dst++;
+ addr += PAGE_SIZE;
+ }
continue;
-
- dpage = dmirror_devmem_alloc_page(mdevice);
- if (!dpage)
- continue;
+ }
rpage = BACKING_PAGE(dpage);
- if (spage)
- copy_highpage(rpage, spage);
- else
- clear_highpage(rpage);
/*
* Normally, a device would use the page->zone_device_data to
@@ -684,10 +747,42 @@ static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
pr_debug("migrating from sys to dev pfn src: 0x%lx pfn dst: 0x%lx\n",
page_to_pfn(spage), page_to_pfn(dpage));
- *dst = migrate_pfn(page_to_pfn(dpage));
- if ((*src & MIGRATE_PFN_WRITE) ||
- (!spage && args->vma->vm_flags & VM_WRITE))
- *dst |= MIGRATE_PFN_WRITE;
+
+ *dst = migrate_pfn(page_to_pfn(dpage)) | write;
+
+ if (is_large) {
+ int i;
+ struct folio *folio = page_folio(dpage);
+ *dst |= MIGRATE_PFN_COMPOUND;
+
+ if (folio_test_large(folio)) {
+ for (i = 0; i < folio_nr_pages(folio); i++) {
+ struct page *dst_page =
+ pfn_to_page(page_to_pfn(rpage) + i);
+ struct page *src_page =
+ pfn_to_page(page_to_pfn(spage) + i);
+
+ if (spage)
+ copy_highpage(dst_page, src_page);
+ else
+ clear_highpage(dst_page);
+ src++;
+ dst++;
+ addr += PAGE_SIZE;
+ }
+ continue;
+ }
+ }
+
+ if (spage)
+ copy_highpage(rpage, spage);
+ else
+ clear_highpage(rpage);
+
+next:
+ src++;
+ dst++;
+ addr += PAGE_SIZE;
}
}
@@ -734,14 +829,17 @@ static int dmirror_migrate_finalize_and_map(struct migrate_vma *args,
const unsigned long *src = args->src;
const unsigned long *dst = args->dst;
unsigned long pfn;
+ const unsigned long start_pfn = start >> PAGE_SHIFT;
+ const unsigned long end_pfn = end >> PAGE_SHIFT;
/* Map the migrated pages into the device's page tables. */
mutex_lock(&dmirror->mutex);
- for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++,
- src++, dst++) {
+ for (pfn = start_pfn; pfn < end_pfn; pfn++, src++, dst++) {
struct page *dpage;
void *entry;
+ int nr, i;
+ struct page *rpage;
if (!(*src & MIGRATE_PFN_MIGRATE))
continue;
@@ -750,13 +848,25 @@ static int dmirror_migrate_finalize_and_map(struct migrate_vma *args,
if (!dpage)
continue;
- entry = BACKING_PAGE(dpage);
- if (*dst & MIGRATE_PFN_WRITE)
- entry = xa_tag_pointer(entry, DPT_XA_TAG_WRITE);
- entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
- if (xa_is_err(entry)) {
- mutex_unlock(&dmirror->mutex);
- return xa_err(entry);
+ if (*dst & MIGRATE_PFN_COMPOUND)
+ nr = folio_nr_pages(page_folio(dpage));
+ else
+ nr = 1;
+
+ WARN_ON_ONCE(end_pfn < start_pfn + nr);
+
+ rpage = BACKING_PAGE(dpage);
+ VM_BUG_ON(folio_nr_pages(page_folio(rpage)) != nr);
+
+ for (i = 0; i < nr; i++) {
+ entry = folio_page(page_folio(rpage), i);
+ if (*dst & MIGRATE_PFN_WRITE)
+ entry = xa_tag_pointer(entry, DPT_XA_TAG_WRITE);
+ entry = xa_store(&dmirror->pt, pfn + i, entry, GFP_ATOMIC);
+ if (xa_is_err(entry)) {
+ mutex_unlock(&dmirror->mutex);
+ return xa_err(entry);
+ }
}
}
@@ -829,31 +939,61 @@ static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
unsigned long start = args->start;
unsigned long end = args->end;
unsigned long addr;
+ unsigned int order = 0;
+ int i;
- for (addr = start; addr < end; addr += PAGE_SIZE,
- src++, dst++) {
+ for (addr = start; addr < end; ) {
struct page *dpage, *spage;
spage = migrate_pfn_to_page(*src);
if (!spage || !(*src & MIGRATE_PFN_MIGRATE))
- continue;
+ goto next;
if (WARN_ON(!is_device_private_page(spage) &&
!is_device_coherent_page(spage)))
- continue;
+ goto next;
spage = BACKING_PAGE(spage);
- dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr);
- if (!dpage)
- continue;
- pr_debug("migrating from dev to sys pfn src: 0x%lx pfn dst: 0x%lx\n",
- page_to_pfn(spage), page_to_pfn(dpage));
+ order = folio_order(page_folio(spage));
+
+ if (order)
+ dpage = folio_page(vma_alloc_folio(GFP_HIGHUSER_MOVABLE,
+ order, args->vma, addr), 0);
+ else
+ dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr);
+
+ /* Try with smaller pages if large allocation fails */
+ if (!dpage && order) {
+ dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr);
+ if (!dpage)
+ return VM_FAULT_OOM;
+ order = 0;
+ }
+ pr_debug("migrating from sys to dev pfn src: 0x%lx pfn dst: 0x%lx\n",
+ page_to_pfn(spage), page_to_pfn(dpage));
lock_page(dpage);
xa_erase(&dmirror->pt, addr >> PAGE_SHIFT);
copy_highpage(dpage, spage);
*dst = migrate_pfn(page_to_pfn(dpage));
if (*src & MIGRATE_PFN_WRITE)
*dst |= MIGRATE_PFN_WRITE;
+ if (order)
+ *dst |= MIGRATE_PFN_COMPOUND;
+
+ for (i = 0; i < (1 << order); i++) {
+ struct page *src_page;
+ struct page *dst_page;
+
+ src_page = pfn_to_page(page_to_pfn(spage) + i);
+ dst_page = pfn_to_page(page_to_pfn(dpage) + i);
+
+ xa_erase(&dmirror->pt, addr >> PAGE_SHIFT);
+ copy_highpage(dst_page, src_page);
+ }
+next:
+ addr += PAGE_SIZE << order;
+ src += 1 << order;
+ dst += 1 << order;
}
return 0;
}
@@ -879,11 +1019,14 @@ static int dmirror_migrate_to_system(struct dmirror *dmirror,
unsigned long size = cmd->npages << PAGE_SHIFT;
struct mm_struct *mm = dmirror->notifier.mm;
struct vm_area_struct *vma;
- unsigned long src_pfns[32] = { 0 };
- unsigned long dst_pfns[32] = { 0 };
struct migrate_vma args = { 0 };
unsigned long next;
int ret;
+ unsigned long *src_pfns;
+ unsigned long *dst_pfns;
+
+ src_pfns = kvcalloc(PTRS_PER_PTE, sizeof(*src_pfns), GFP_KERNEL | __GFP_NOFAIL);
+ dst_pfns = kvcalloc(PTRS_PER_PTE, sizeof(*dst_pfns), GFP_KERNEL | __GFP_NOFAIL);
start = cmd->addr;
end = start + size;
@@ -902,7 +1045,7 @@ static int dmirror_migrate_to_system(struct dmirror *dmirror,
ret = -EINVAL;
goto out;
}
- next = min(end, addr + (ARRAY_SIZE(src_pfns) << PAGE_SHIFT));
+ next = min(end, addr + (PTRS_PER_PTE << PAGE_SHIFT));
if (next > vma->vm_end)
next = vma->vm_end;
@@ -912,7 +1055,7 @@ static int dmirror_migrate_to_system(struct dmirror *dmirror,
args.start = addr;
args.end = next;
args.pgmap_owner = dmirror->mdevice;
- args.flags = dmirror_select_device(dmirror);
+ args.flags = dmirror_select_device(dmirror) | MIGRATE_VMA_SELECT_COMPOUND;
ret = migrate_vma_setup(&args);
if (ret)
@@ -928,6 +1071,8 @@ static int dmirror_migrate_to_system(struct dmirror *dmirror,
out:
mmap_read_unlock(mm);
mmput(mm);
+ kvfree(src_pfns);
+ kvfree(dst_pfns);
return ret;
}
@@ -939,12 +1084,12 @@ static int dmirror_migrate_to_device(struct dmirror *dmirror,
unsigned long size = cmd->npages << PAGE_SHIFT;
struct mm_struct *mm = dmirror->notifier.mm;
struct vm_area_struct *vma;
- unsigned long src_pfns[32] = { 0 };
- unsigned long dst_pfns[32] = { 0 };
struct dmirror_bounce bounce;
struct migrate_vma args = { 0 };
unsigned long next;
int ret;
+ unsigned long *src_pfns;
+ unsigned long *dst_pfns;
start = cmd->addr;
end = start + size;
@@ -955,6 +1100,18 @@ static int dmirror_migrate_to_device(struct dmirror *dmirror,
if (!mmget_not_zero(mm))
return -EINVAL;
+ ret = -ENOMEM;
+ src_pfns = kvcalloc(PTRS_PER_PTE, sizeof(*src_pfns),
+ GFP_KERNEL | __GFP_NOFAIL);
+ if (!src_pfns)
+ goto free_mem;
+
+ dst_pfns = kvcalloc(PTRS_PER_PTE, sizeof(*dst_pfns),
+ GFP_KERNEL | __GFP_NOFAIL);
+ if (!dst_pfns)
+ goto free_mem;
+
+ ret = 0;
mmap_read_lock(mm);
for (addr = start; addr < end; addr = next) {
vma = vma_lookup(mm, addr);
@@ -962,7 +1119,7 @@ static int dmirror_migrate_to_device(struct dmirror *dmirror,
ret = -EINVAL;
goto out;
}
- next = min(end, addr + (ARRAY_SIZE(src_pfns) << PAGE_SHIFT));
+ next = min(end, addr + (PTRS_PER_PTE << PAGE_SHIFT));
if (next > vma->vm_end)
next = vma->vm_end;
@@ -972,7 +1129,8 @@ static int dmirror_migrate_to_device(struct dmirror *dmirror,
args.start = addr;
args.end = next;
args.pgmap_owner = dmirror->mdevice;
- args.flags = MIGRATE_VMA_SELECT_SYSTEM;
+ args.flags = MIGRATE_VMA_SELECT_SYSTEM |
+ MIGRATE_VMA_SELECT_COMPOUND;
ret = migrate_vma_setup(&args);
if (ret)
goto out;
@@ -992,7 +1150,7 @@ static int dmirror_migrate_to_device(struct dmirror *dmirror,
*/
ret = dmirror_bounce_init(&bounce, start, size);
if (ret)
- return ret;
+ goto free_mem;
mutex_lock(&dmirror->mutex);
ret = dmirror_do_read(dmirror, start, end, &bounce);
mutex_unlock(&dmirror->mutex);
@@ -1003,11 +1161,14 @@ static int dmirror_migrate_to_device(struct dmirror *dmirror,
}
cmd->cpages = bounce.cpages;
dmirror_bounce_fini(&bounce);
- return ret;
+ goto free_mem;
out:
mmap_read_unlock(mm);
mmput(mm);
+free_mem:
+ kfree(src_pfns);
+ kfree(dst_pfns);
return ret;
}
@@ -1200,6 +1361,7 @@ static void dmirror_device_evict_chunk(struct dmirror_chunk *chunk)
unsigned long i;
unsigned long *src_pfns;
unsigned long *dst_pfns;
+ unsigned int order = 0;
src_pfns = kvcalloc(npages, sizeof(*src_pfns), GFP_KERNEL | __GFP_NOFAIL);
dst_pfns = kvcalloc(npages, sizeof(*dst_pfns), GFP_KERNEL | __GFP_NOFAIL);
@@ -1215,13 +1377,25 @@ static void dmirror_device_evict_chunk(struct dmirror_chunk *chunk)
if (WARN_ON(!is_device_private_page(spage) &&
!is_device_coherent_page(spage)))
continue;
+
+ order = folio_order(page_folio(spage));
spage = BACKING_PAGE(spage);
- dpage = alloc_page(GFP_HIGHUSER_MOVABLE | __GFP_NOFAIL);
+ if (src_pfns[i] & MIGRATE_PFN_COMPOUND) {
+ dpage = folio_page(folio_alloc(GFP_HIGHUSER_MOVABLE,
+ order), 0);
+ } else {
+ dpage = alloc_page(GFP_HIGHUSER_MOVABLE | __GFP_NOFAIL);
+ order = 0;
+ }
+
+ /* TODO Support splitting here */
lock_page(dpage);
- copy_highpage(dpage, spage);
dst_pfns[i] = migrate_pfn(page_to_pfn(dpage));
if (src_pfns[i] & MIGRATE_PFN_WRITE)
dst_pfns[i] |= MIGRATE_PFN_WRITE;
+ if (order)
+ dst_pfns[i] |= MIGRATE_PFN_COMPOUND;
+ folio_copy(page_folio(dpage), page_folio(spage));
}
migrate_device_pages(src_pfns, dst_pfns, npages);
migrate_device_finalize(src_pfns, dst_pfns, npages);
@@ -1234,7 +1408,12 @@ static void dmirror_remove_free_pages(struct dmirror_chunk *devmem)
{
struct dmirror_device *mdevice = devmem->mdevice;
struct page *page;
+ struct folio *folio;
+
+ for (folio = mdevice->free_folios; folio; folio = folio_zone_device_data(folio))
+ if (dmirror_page_to_chunk(folio_page(folio, 0)) == devmem)
+ mdevice->free_folios = folio_zone_device_data(folio);
for (page = mdevice->free_pages; page; page = page->zone_device_data)
if (dmirror_page_to_chunk(page) == devmem)
mdevice->free_pages = page->zone_device_data;
@@ -1265,6 +1444,7 @@ static void dmirror_device_remove_chunks(struct dmirror_device *mdevice)
mdevice->devmem_count = 0;
mdevice->devmem_capacity = 0;
mdevice->free_pages = NULL;
+ mdevice->free_folios = NULL;
kfree(mdevice->devmem_chunks);
mdevice->devmem_chunks = NULL;
}
@@ -1378,18 +1558,30 @@ static void dmirror_devmem_free(struct page *page)
{
struct page *rpage = BACKING_PAGE(page);
struct dmirror_device *mdevice;
+ struct folio *folio = page_folio(rpage);
+ unsigned int order = folio_order(folio);
- if (rpage != page)
- __free_page(rpage);
+ if (rpage != page) {
+ if (order)
+ __free_pages(rpage, order);
+ else
+ __free_page(rpage);
+ rpage = NULL;
+ }
mdevice = dmirror_page_to_device(page);
spin_lock(&mdevice->lock);
/* Return page to our allocator if not freeing the chunk */
if (!dmirror_page_to_chunk(page)->remove) {
- mdevice->cfree++;
- page->zone_device_data = mdevice->free_pages;
- mdevice->free_pages = page;
+ mdevice->cfree += 1 << order;
+ if (order) {
+ page->zone_device_data = mdevice->free_folios;
+ mdevice->free_folios = page_folio(page);
+ } else {
+ page->zone_device_data = mdevice->free_pages;
+ mdevice->free_pages = page;
+ }
}
spin_unlock(&mdevice->lock);
}
@@ -1397,11 +1589,10 @@ static void dmirror_devmem_free(struct page *page)
static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
{
struct migrate_vma args = { 0 };
- unsigned long src_pfns = 0;
- unsigned long dst_pfns = 0;
struct page *rpage;
struct dmirror *dmirror;
- vm_fault_t ret;
+ vm_fault_t ret = 0;
+ unsigned int order, nr;
/*
* Normally, a device would use the page->zone_device_data to point to
@@ -1412,21 +1603,36 @@ static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
dmirror = rpage->zone_device_data;
/* FIXME demonstrate how we can adjust migrate range */
+ order = folio_order(page_folio(vmf->page));
+ nr = 1 << order;
+
+ /*
+ * Consider a per-cpu cache of src and dst pfns, but with
+ * large number of cpus that might not scale well.
+ */
+ args.start = ALIGN_DOWN(vmf->address, (1 << (PAGE_SHIFT + order)));
args.vma = vmf->vma;
- args.start = vmf->address;
- args.end = args.start + PAGE_SIZE;
- args.src = &src_pfns;
- args.dst = &dst_pfns;
+ args.end = args.start + (PAGE_SIZE << order);
+ args.src = kcalloc(nr, sizeof(*args.src), GFP_KERNEL);
+ args.dst = kcalloc(nr, sizeof(*args.dst), GFP_KERNEL);
args.pgmap_owner = dmirror->mdevice;
args.flags = dmirror_select_device(dmirror);
args.fault_page = vmf->page;
+ if (!args.src || !args.dst) {
+ ret = VM_FAULT_OOM;
+ goto err;
+ }
+
+ if (order)
+ args.flags |= MIGRATE_VMA_SELECT_COMPOUND;
+
if (migrate_vma_setup(&args))
return VM_FAULT_SIGBUS;
ret = dmirror_devmem_fault_alloc_and_copy(&args, dmirror);
if (ret)
- return ret;
+ goto err;
migrate_vma_pages(&args);
/*
* No device finalize step is needed since
@@ -1434,7 +1640,10 @@ static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
* invalidated the device page table.
*/
migrate_vma_finalize(&args);
- return 0;
+err:
+ kfree(args.src);
+ kfree(args.dst);
+ return ret;
}
static const struct dev_pagemap_ops dmirror_devmem_ops = {
@@ -1465,7 +1674,7 @@ static int dmirror_device_init(struct dmirror_device *mdevice, int id)
return ret;
/* Build a list of free ZONE_DEVICE struct pages */
- return dmirror_allocate_chunk(mdevice, NULL);
+ return dmirror_allocate_chunk(mdevice, NULL, false);
}
static void dmirror_device_remove(struct dmirror_device *mdevice)
--
2.49.0
^ permalink raw reply related [flat|nested] 15+ messages in thread
* [v1 07/12] mm/memremap: add folio_split support
2025-07-03 22:27 [v1 00/12] THP support for zone device page migration Balbir Singh
` (5 preceding siblings ...)
2025-07-03 22:27 ` [v1 06/12] lib/test_hmm: test cases and support for zone device private THP Balbir Singh
@ 2025-07-03 22:27 ` Balbir Singh
2025-07-03 22:27 ` [v1 08/12] mm/thp: add split during migration support Balbir Singh
` (5 subsequent siblings)
12 siblings, 0 replies; 15+ messages in thread
From: Balbir Singh @ 2025-07-03 22:27 UTC (permalink / raw)
To: linux-mm; +Cc: akpm, linux-kernel, Balbir Singh
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 smaller order.
The HMM test driver has been updated to handle the split, since the
test driver uses backing pages, it 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 <balbirs@nvidia.com>
---
include/linux/memremap.h | 7 +++++++
include/linux/mm.h | 1 +
lib/test_hmm.c | 42 ++++++++++++++++++++++++++++++++++++++++
mm/huge_memory.c | 14 ++++++++++++++
mm/page_alloc.c | 1 +
5 files changed, 65 insertions(+)
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 11d586dd8ef1..2091b754f1da 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -100,6 +100,13 @@ struct dev_pagemap_ops {
*/
int (*memory_failure)(struct dev_pagemap *pgmap, unsigned long pfn,
unsigned long nr_pages, int mf_flags);
+
+ /*
+ * Used for private (un-addressable) device memory only.
+ * This callback is used when a folio is split into
+ * a smaller folio
+ */
+ void (*folio_split)(struct folio *head, struct folio *tail);
};
#define PGMAP_ALTMAP_VALID (1 << 0)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ef40f68c1183..f7bda8b1e46c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1183,6 +1183,7 @@ static inline struct folio *virt_to_folio(const void *x)
void __folio_put(struct folio *folio);
void split_page(struct page *page, unsigned int order);
+void prep_compound_page(struct page *page, unsigned int order);
void folio_copy(struct folio *dst, struct folio *src);
int folio_mc_copy(struct folio *dst, struct folio *src);
diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index 95b4276a17fd..e20021fb7c69 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -1646,9 +1646,51 @@ static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
return ret;
}
+static void dmirror_devmem_folio_split(struct folio *head, struct folio *tail)
+{
+ struct page *rpage = BACKING_PAGE(folio_page(head, 0));
+ struct page *rpage_tail;
+ struct folio *rfolio;
+ unsigned long offset = 0;
+ unsigned int tail_order;
+ unsigned int head_order = folio_order(head);
+
+ if (!rpage) {
+ tail->page.zone_device_data = NULL;
+ return;
+ }
+
+ rfolio = page_folio(rpage);
+
+ if (tail == NULL) {
+ folio_reset_order(rfolio);
+ rfolio->mapping = NULL;
+ if (head_order)
+ prep_compound_page(rpage, head_order);
+ folio_set_count(rfolio, 1 << head_order);
+ return;
+ }
+
+ offset = folio_pfn(tail) - folio_pfn(head);
+
+ rpage_tail = folio_page(rfolio, offset);
+ tail->page.zone_device_data = rpage_tail;
+ clear_compound_head(rpage_tail);
+ rpage_tail->mapping = NULL;
+
+ tail_order = folio_order(tail);
+ if (tail_order)
+ prep_compound_page(rpage_tail, tail_order);
+
+ folio_page(tail, 0)->mapping = folio_page(head, 0)->mapping;
+ tail->pgmap = head->pgmap;
+ folio_set_count(page_folio(rpage_tail), 1 << tail_order);
+}
+
static const struct dev_pagemap_ops dmirror_devmem_ops = {
.page_free = dmirror_devmem_free,
.migrate_to_ram = dmirror_devmem_fault,
+ .folio_split = dmirror_devmem_folio_split,
};
static int dmirror_device_init(struct dmirror_device *mdevice, int id)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index f29add796931..d55e36ae0c39 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3630,6 +3630,11 @@ static int __split_unmapped_folio(struct folio *folio, int new_order,
if (release == origin_folio)
continue;
+ if (folio_is_device_private(origin_folio) &&
+ origin_folio->pgmap->ops->folio_split)
+ origin_folio->pgmap->ops->folio_split(
+ origin_folio, release);
+
folio_ref_unfreeze(release, 1 +
((mapping || swap_cache) ?
folio_nr_pages(release) : 0));
@@ -3661,6 +3666,15 @@ static int __split_unmapped_folio(struct folio *folio, int new_order,
}
}
+ /*
+ * Mark the end of the split, so that the driver can setup origin_folio's
+ * order and other metadata
+ */
+ if (folio_is_device_private(origin_folio) &&
+ origin_folio->pgmap->ops->folio_split)
+ origin_folio->pgmap->ops->folio_split(
+ origin_folio, NULL);
+
/*
* Unfreeze origin_folio only after all page cache entries, which used
* to point to it, have been updated with new folios. Otherwise,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 4f55f8ed65c7..0a538e9c24bd 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -722,6 +722,7 @@ void prep_compound_page(struct page *page, unsigned int order)
prep_compound_head(page, order);
}
+EXPORT_SYMBOL_GPL(prep_compound_page);
static inline void set_buddy_order(struct page *page, unsigned int order)
{
--
2.49.0
^ permalink raw reply related [flat|nested] 15+ messages in thread
* [v1 08/12] mm/thp: add split during migration support
2025-07-03 22:27 [v1 00/12] THP support for zone device page migration Balbir Singh
` (6 preceding siblings ...)
2025-07-03 22:27 ` [v1 07/12] mm/memremap: add folio_split support Balbir Singh
@ 2025-07-03 22:27 ` Balbir Singh
2025-07-03 22:27 ` [v1 09/12] lib/test_hmm: add test case for split pages Balbir Singh
` (4 subsequent siblings)
12 siblings, 0 replies; 15+ messages in thread
From: Balbir Singh @ 2025-07-03 22:27 UTC (permalink / raw)
To: linux-mm; +Cc: akpm, linux-kernel, Balbir Singh
Support splitting pages during THP zone device migration as needed.
The common case that arises is that after setup, during migrate
the destination might not be able to allocate MIGRATE_PFN_COMPOUND
pages.
Add a new routine migrate_vma_split_pages() to support the splitting
of already isolated pages. The pages being migrated are already unmapped
and marked for migration during setup (via unmap). folio_split() and
__split_unmapped_folio() take additional isolated arguments, to avoid
unmapping and remaping these pages and unlocking/putting the folio.
Signed-off-by: Balbir Singh <balbirs@nvidia.com>
---
include/linux/huge_mm.h | 11 ++++++--
mm/huge_memory.c | 54 ++++++++++++++++++++-----------------
mm/migrate_device.c | 59 ++++++++++++++++++++++++++++++++---------
3 files changed, 85 insertions(+), 39 deletions(-)
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 65a1bdf29bb9..5f55a754e57c 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -343,8 +343,8 @@ unsigned long thp_get_unmapped_area_vmflags(struct file *filp, unsigned long add
vm_flags_t vm_flags);
bool can_split_folio(struct folio *folio, int caller_pins, int *pextra_pins);
-int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
- unsigned int new_order);
+int __split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
+ unsigned int new_order, bool isolated);
int min_order_for_split(struct folio *folio);
int split_folio_to_list(struct folio *folio, struct list_head *list);
bool uniform_split_supported(struct folio *folio, unsigned int new_order,
@@ -353,6 +353,13 @@ bool non_uniform_split_supported(struct folio *folio, unsigned int new_order,
bool warns);
int folio_split(struct folio *folio, unsigned int new_order, struct page *page,
struct list_head *list);
+
+static inline int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
+ unsigned int new_order)
+{
+ return __split_huge_page_to_list_to_order(page, list, new_order, false);
+}
+
/*
* try_folio_split - try to split a @folio at @page using non uniform split.
* @folio: folio to be split
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index d55e36ae0c39..e00ddfed22fa 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3424,15 +3424,6 @@ static void __split_folio_to_order(struct folio *folio, int old_order,
new_folio->mapping = folio->mapping;
new_folio->index = folio->index + i;
- /*
- * page->private should not be set in tail pages. Fix up and warn once
- * if private is unexpectedly set.
- */
- if (unlikely(new_folio->private)) {
- VM_WARN_ON_ONCE_PAGE(true, new_head);
- new_folio->private = NULL;
- }
-
if (folio_test_swapcache(folio))
new_folio->swap.val = folio->swap.val + i;
@@ -3519,7 +3510,7 @@ static int __split_unmapped_folio(struct folio *folio, int new_order,
struct page *split_at, struct page *lock_at,
struct list_head *list, pgoff_t end,
struct xa_state *xas, struct address_space *mapping,
- bool uniform_split)
+ bool uniform_split, bool isolated)
{
struct lruvec *lruvec;
struct address_space *swap_cache = NULL;
@@ -3643,8 +3634,9 @@ static int __split_unmapped_folio(struct folio *folio, int new_order,
percpu_ref_get_many(&release->pgmap->ref,
(1 << new_order) - 1);
- lru_add_split_folio(origin_folio, release, lruvec,
- list);
+ if (!isolated)
+ lru_add_split_folio(origin_folio, release,
+ lruvec, list);
/* Some pages can be beyond EOF: drop them from cache */
if (release->index >= end) {
@@ -3697,6 +3689,12 @@ static int __split_unmapped_folio(struct folio *folio, int new_order,
if (nr_dropped)
shmem_uncharge(mapping->host, nr_dropped);
+ /*
+ * Don't remap and unlock isolated folios
+ */
+ if (isolated)
+ return ret;
+
remap_page(origin_folio, 1 << order,
folio_test_anon(origin_folio) ?
RMP_USE_SHARED_ZEROPAGE : 0);
@@ -3790,6 +3788,7 @@ bool uniform_split_supported(struct folio *folio, unsigned int new_order,
* @lock_at: a page within @folio to be left locked to caller
* @list: after-split folios will be put on it if non NULL
* @uniform_split: perform uniform split or not (non-uniform split)
+ * @isolated: The pages are already unmapped
*
* It calls __split_unmapped_folio() to perform uniform and non-uniform split.
* It is in charge of checking whether the split is supported or not and
@@ -3800,7 +3799,7 @@ bool uniform_split_supported(struct folio *folio, unsigned int new_order,
*/
static int __folio_split(struct folio *folio, unsigned int new_order,
struct page *split_at, struct page *lock_at,
- struct list_head *list, bool uniform_split)
+ struct list_head *list, bool uniform_split, bool isolated)
{
struct deferred_split *ds_queue = get_deferred_split_queue(folio);
XA_STATE(xas, &folio->mapping->i_pages, folio->index);
@@ -3846,14 +3845,16 @@ static int __folio_split(struct folio *folio, unsigned int new_order,
* is taken to serialise against parallel split or collapse
* operations.
*/
- anon_vma = folio_get_anon_vma(folio);
- if (!anon_vma) {
- ret = -EBUSY;
- goto out;
+ if (!isolated) {
+ anon_vma = folio_get_anon_vma(folio);
+ if (!anon_vma) {
+ ret = -EBUSY;
+ goto out;
+ }
+ anon_vma_lock_write(anon_vma);
}
end = -1;
mapping = NULL;
- anon_vma_lock_write(anon_vma);
} else {
unsigned int min_order;
gfp_t gfp;
@@ -3920,7 +3921,8 @@ static int __folio_split(struct folio *folio, unsigned int new_order,
goto out_unlock;
}
- unmap_folio(folio);
+ if (!isolated)
+ unmap_folio(folio);
/* block interrupt reentry in xa_lock and spinlock */
local_irq_disable();
@@ -3973,14 +3975,15 @@ static int __folio_split(struct folio *folio, unsigned int new_order,
ret = __split_unmapped_folio(folio, new_order,
split_at, lock_at, list, end, &xas, mapping,
- uniform_split);
+ uniform_split, isolated);
} else {
spin_unlock(&ds_queue->split_queue_lock);
fail:
if (mapping)
xas_unlock(&xas);
local_irq_enable();
- remap_page(folio, folio_nr_pages(folio), 0);
+ if (!isolated)
+ remap_page(folio, folio_nr_pages(folio), 0);
ret = -EAGAIN;
}
@@ -4046,12 +4049,13 @@ static int __folio_split(struct folio *folio, unsigned int new_order,
* Returns -EINVAL when trying to split to an order that is incompatible
* with the folio. Splitting to order 0 is compatible with all folios.
*/
-int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
- unsigned int new_order)
+int __split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
+ unsigned int new_order, bool isolated)
{
struct folio *folio = page_folio(page);
- return __folio_split(folio, new_order, &folio->page, page, list, true);
+ return __folio_split(folio, new_order, &folio->page, page, list, true,
+ isolated);
}
/*
@@ -4080,7 +4084,7 @@ int folio_split(struct folio *folio, unsigned int new_order,
struct page *split_at, struct list_head *list)
{
return __folio_split(folio, new_order, split_at, &folio->page, list,
- false);
+ false, false);
}
int min_order_for_split(struct folio *folio)
diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index 41d0bd787969..acd2f03b178d 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -813,6 +813,24 @@ static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate,
src[i] &= ~MIGRATE_PFN_MIGRATE;
return 0;
}
+
+static void migrate_vma_split_pages(struct migrate_vma *migrate,
+ unsigned long idx, unsigned long addr,
+ struct folio *folio)
+{
+ unsigned long i;
+ unsigned long pfn;
+ unsigned long flags;
+
+ folio_get(folio);
+ split_huge_pmd_address(migrate->vma, addr, true);
+ __split_huge_page_to_list_to_order(folio_page(folio, 0), NULL, 0, true);
+ migrate->src[idx] &= ~MIGRATE_PFN_COMPOUND;
+ flags = migrate->src[idx] & ((1UL << MIGRATE_PFN_SHIFT) - 1);
+ pfn = migrate->src[idx] >> MIGRATE_PFN_SHIFT;
+ for (i = 1; i < HPAGE_PMD_NR; i++)
+ migrate->src[i+idx] = migrate_pfn(pfn + i) | flags;
+}
#else /* !CONFIG_ARCH_ENABLE_THP_MIGRATION */
static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate,
unsigned long addr,
@@ -822,6 +840,11 @@ static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate,
{
return 0;
}
+
+static void migrate_vma_split_pages(struct migrate_vma *migrate,
+ unsigned long idx, unsigned long addr,
+ struct folio *folio)
+{}
#endif
/*
@@ -971,8 +994,9 @@ static void __migrate_device_pages(unsigned long *src_pfns,
struct migrate_vma *migrate)
{
struct mmu_notifier_range range;
- unsigned long i;
+ unsigned long i, j;
bool notified = false;
+ unsigned long addr;
for (i = 0; i < npages; ) {
struct page *newpage = migrate_pfn_to_page(dst_pfns[i]);
@@ -1014,12 +1038,16 @@ static void __migrate_device_pages(unsigned long *src_pfns,
(!(dst_pfns[i] & MIGRATE_PFN_COMPOUND))) {
nr = HPAGE_PMD_NR;
src_pfns[i] &= ~MIGRATE_PFN_COMPOUND;
- src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
- goto next;
+ } else {
+ nr = 1;
}
- migrate_vma_insert_page(migrate, addr, &dst_pfns[i],
- &src_pfns[i]);
+ for (j = 0; j < nr && i + j < npages; j++) {
+ src_pfns[i+j] |= MIGRATE_PFN_MIGRATE;
+ migrate_vma_insert_page(migrate,
+ addr + j * PAGE_SIZE,
+ &dst_pfns[i+j], &src_pfns[i+j]);
+ }
goto next;
}
@@ -1041,7 +1069,9 @@ static void __migrate_device_pages(unsigned long *src_pfns,
MIGRATE_PFN_COMPOUND);
goto next;
}
- src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
+ nr = 1 << folio_order(folio);
+ addr = migrate->start + i * PAGE_SIZE;
+ migrate_vma_split_pages(migrate, i, addr, folio);
} else if ((src_pfns[i] & MIGRATE_PFN_MIGRATE) &&
(dst_pfns[i] & MIGRATE_PFN_COMPOUND) &&
!(src_pfns[i] & MIGRATE_PFN_COMPOUND)) {
@@ -1076,12 +1106,17 @@ static void __migrate_device_pages(unsigned long *src_pfns,
BUG_ON(folio_test_writeback(folio));
if (migrate && migrate->fault_page == page)
- extra_cnt = 1;
- r = folio_migrate_mapping(mapping, newfolio, folio, extra_cnt);
- if (r != MIGRATEPAGE_SUCCESS)
- src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
- else
- folio_migrate_flags(newfolio, folio);
+ extra_cnt++;
+ for (j = 0; j < nr && i + j < npages; j++) {
+ folio = page_folio(migrate_pfn_to_page(src_pfns[i+j]));
+ newfolio = page_folio(migrate_pfn_to_page(dst_pfns[i+j]));
+
+ r = folio_migrate_mapping(mapping, newfolio, folio, extra_cnt);
+ if (r != MIGRATEPAGE_SUCCESS)
+ src_pfns[i+j] &= ~MIGRATE_PFN_MIGRATE;
+ else
+ folio_migrate_flags(newfolio, folio);
+ }
next:
i += nr;
}
--
2.49.0
^ permalink raw reply related [flat|nested] 15+ messages in thread
* [v1 09/12] lib/test_hmm: add test case for split pages
2025-07-03 22:27 [v1 00/12] THP support for zone device page migration Balbir Singh
` (7 preceding siblings ...)
2025-07-03 22:27 ` [v1 08/12] mm/thp: add split during migration support Balbir Singh
@ 2025-07-03 22:27 ` Balbir Singh
2025-07-03 22:27 ` [v1 10/12] selftests/mm/hmm-tests: new tests for zone device THP migration Balbir Singh
` (3 subsequent siblings)
12 siblings, 0 replies; 15+ messages in thread
From: Balbir Singh @ 2025-07-03 22:27 UTC (permalink / raw)
To: linux-mm; +Cc: akpm, linux-kernel, Balbir Singh
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 <balbirs@nvidia.com>
---
lib/test_hmm.c | 61 ++++++++++++++++++++++++++++++---------------
lib/test_hmm_uapi.h | 3 +++
2 files changed, 44 insertions(+), 20 deletions(-)
diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index e20021fb7c69..c322be89d54c 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -92,6 +92,7 @@ struct dmirror {
struct xarray pt;
struct mmu_interval_notifier notifier;
struct mutex mutex;
+ __u64 flags;
};
/*
@@ -699,7 +700,12 @@ static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
page_to_pfn(spage)))
goto next;
- dpage = dmirror_devmem_alloc_page(dmirror, is_large);
+ if (dmirror->flags & HMM_DMIRROR_FLAG_FAIL_ALLOC) {
+ dmirror->flags &= ~HMM_DMIRROR_FLAG_FAIL_ALLOC;
+ dpage = NULL;
+ } else
+ dpage = dmirror_devmem_alloc_page(dmirror, is_large);
+
if (!dpage) {
struct folio *folio;
unsigned long i;
@@ -954,44 +960,55 @@ static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
goto next;
spage = BACKING_PAGE(spage);
order = folio_order(page_folio(spage));
-
if (order)
+ *dst = MIGRATE_PFN_COMPOUND;
+ if (*src & MIGRATE_PFN_WRITE)
+ *dst |= MIGRATE_PFN_WRITE;
+
+ if (dmirror->flags & HMM_DMIRROR_FLAG_FAIL_ALLOC) {
+ dmirror->flags &= ~HMM_DMIRROR_FLAG_FAIL_ALLOC;
+ *dst &= ~MIGRATE_PFN_COMPOUND;
+ dpage = NULL;
+ } else if (order) {
dpage = folio_page(vma_alloc_folio(GFP_HIGHUSER_MOVABLE,
order, args->vma, addr), 0);
- else
- dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr);
-
- /* Try with smaller pages if large allocation fails */
- if (!dpage && order) {
+ } else {
dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr);
- if (!dpage)
- return VM_FAULT_OOM;
- order = 0;
}
+ if (!dpage && !order)
+ return VM_FAULT_OOM;
+
pr_debug("migrating from sys to dev pfn src: 0x%lx pfn dst: 0x%lx\n",
page_to_pfn(spage), page_to_pfn(dpage));
- lock_page(dpage);
- xa_erase(&dmirror->pt, addr >> PAGE_SHIFT);
- copy_highpage(dpage, spage);
- *dst = migrate_pfn(page_to_pfn(dpage));
- if (*src & MIGRATE_PFN_WRITE)
- *dst |= MIGRATE_PFN_WRITE;
- if (order)
- *dst |= MIGRATE_PFN_COMPOUND;
+
+ if (dpage) {
+ lock_page(dpage);
+ *dst |= migrate_pfn(page_to_pfn(dpage));
+ }
for (i = 0; i < (1 << order); i++) {
struct page *src_page;
struct page *dst_page;
+ /* Try with smaller pages if large allocation fails */
+ if (!dpage && order) {
+ dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr);
+ lock_page(dpage);
+ dst[i] = migrate_pfn(page_to_pfn(dpage));
+ dst_page = pfn_to_page(page_to_pfn(dpage));
+ dpage = NULL; /* For the next iteration */
+ } else {
+ dst_page = pfn_to_page(page_to_pfn(dpage) + i);
+ }
+
src_page = pfn_to_page(page_to_pfn(spage) + i);
- dst_page = pfn_to_page(page_to_pfn(dpage) + i);
xa_erase(&dmirror->pt, addr >> PAGE_SHIFT);
+ addr += PAGE_SIZE;
copy_highpage(dst_page, src_page);
}
next:
- addr += PAGE_SIZE << order;
src += 1 << order;
dst += 1 << order;
}
@@ -1509,6 +1526,10 @@ static long dmirror_fops_unlocked_ioctl(struct file *filp,
dmirror_device_remove_chunks(dmirror->mdevice);
ret = 0;
break;
+ case HMM_DMIRROR_FLAGS:
+ dmirror->flags = cmd.npages;
+ ret = 0;
+ break;
default:
return -EINVAL;
diff --git a/lib/test_hmm_uapi.h b/lib/test_hmm_uapi.h
index 8c818a2cf4f6..f94c6d457338 100644
--- a/lib/test_hmm_uapi.h
+++ b/lib/test_hmm_uapi.h
@@ -37,6 +37,9 @@ struct hmm_dmirror_cmd {
#define HMM_DMIRROR_EXCLUSIVE _IOWR('H', 0x05, struct hmm_dmirror_cmd)
#define HMM_DMIRROR_CHECK_EXCLUSIVE _IOWR('H', 0x06, struct hmm_dmirror_cmd)
#define HMM_DMIRROR_RELEASE _IOWR('H', 0x07, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_FLAGS _IOWR('H', 0x08, struct hmm_dmirror_cmd)
+
+#define HMM_DMIRROR_FLAG_FAIL_ALLOC (1ULL << 0)
/*
* Values returned in hmm_dmirror_cmd.ptr for HMM_DMIRROR_SNAPSHOT.
--
2.49.0
^ permalink raw reply related [flat|nested] 15+ messages in thread
* [v1 10/12] selftests/mm/hmm-tests: new tests for zone device THP migration
2025-07-03 22:27 [v1 00/12] THP support for zone device page migration Balbir Singh
` (8 preceding siblings ...)
2025-07-03 22:27 ` [v1 09/12] lib/test_hmm: add test case for split pages Balbir Singh
@ 2025-07-03 22:27 ` Balbir Singh
2025-07-03 22:27 ` [v1 11/12] gpu/drm/nouveau: add THP migration support Balbir Singh
` (2 subsequent siblings)
12 siblings, 0 replies; 15+ messages in thread
From: Balbir Singh @ 2025-07-03 22:27 UTC (permalink / raw)
To: linux-mm; +Cc: akpm, linux-kernel, Balbir Singh
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 <balbirs@nvidia.com>
---
tools/testing/selftests/mm/hmm-tests.c | 410 +++++++++++++++++++++++++
1 file changed, 410 insertions(+)
diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftests/mm/hmm-tests.c
index 141bf63cbe05..da3322a1282c 100644
--- a/tools/testing/selftests/mm/hmm-tests.c
+++ b/tools/testing/selftests/mm/hmm-tests.c
@@ -2056,4 +2056,414 @@ TEST_F(hmm, hmm_cow_in_device)
hmm_buffer_free(buffer);
}
+
+/*
+ * Migrate private anonymous huge empty page.
+ */
+TEST_F(hmm, migrate_anon_huge_empty)
+{
+ struct hmm_buffer *buffer;
+ unsigned long npages;
+ unsigned long size;
+ unsigned long i;
+ void *old_ptr;
+ void *map;
+ int *ptr;
+ int ret;
+
+ size = TWOMEG;
+
+ buffer = malloc(sizeof(*buffer));
+ ASSERT_NE(buffer, NULL);
+
+ buffer->fd = -1;
+ buffer->size = 2 * size;
+ buffer->mirror = malloc(size);
+ ASSERT_NE(buffer->mirror, NULL);
+ memset(buffer->mirror, 0xFF, size);
+
+ buffer->ptr = mmap(NULL, 2 * size,
+ PROT_READ,
+ MAP_PRIVATE | MAP_ANONYMOUS,
+ buffer->fd, 0);
+ ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+ npages = size >> self->page_shift;
+ map = (void *)ALIGN((uintptr_t)buffer->ptr, size);
+ ret = madvise(map, size, MADV_HUGEPAGE);
+ ASSERT_EQ(ret, 0);
+ old_ptr = buffer->ptr;
+ buffer->ptr = map;
+
+ /* Migrate memory to device. */
+ ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+ ASSERT_EQ(ret, 0);
+ ASSERT_EQ(buffer->cpages, npages);
+
+ /* Check what the device read. */
+ for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+ ASSERT_EQ(ptr[i], 0);
+
+ buffer->ptr = old_ptr;
+ hmm_buffer_free(buffer);
+}
+
+/*
+ * Migrate private anonymous huge zero page.
+ */
+TEST_F(hmm, migrate_anon_huge_zero)
+{
+ struct hmm_buffer *buffer;
+ unsigned long npages;
+ unsigned long size;
+ unsigned long i;
+ void *old_ptr;
+ void *map;
+ int *ptr;
+ int ret;
+ int val;
+
+ size = TWOMEG;
+
+ buffer = malloc(sizeof(*buffer));
+ ASSERT_NE(buffer, NULL);
+
+ buffer->fd = -1;
+ buffer->size = 2 * size;
+ buffer->mirror = malloc(size);
+ ASSERT_NE(buffer->mirror, NULL);
+ memset(buffer->mirror, 0xFF, size);
+
+ buffer->ptr = mmap(NULL, 2 * size,
+ PROT_READ,
+ MAP_PRIVATE | MAP_ANONYMOUS,
+ buffer->fd, 0);
+ ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+ npages = size >> self->page_shift;
+ map = (void *)ALIGN((uintptr_t)buffer->ptr, size);
+ ret = madvise(map, size, MADV_HUGEPAGE);
+ ASSERT_EQ(ret, 0);
+ old_ptr = buffer->ptr;
+ buffer->ptr = map;
+
+ /* Initialize a read-only zero huge page. */
+ val = *(int *)buffer->ptr;
+ ASSERT_EQ(val, 0);
+
+ /* Migrate memory to device. */
+ ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+ ASSERT_EQ(ret, 0);
+ ASSERT_EQ(buffer->cpages, npages);
+
+ /* Check what the device read. */
+ for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+ ASSERT_EQ(ptr[i], 0);
+
+ /* Fault pages back to system memory and check them. */
+ for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i) {
+ ASSERT_EQ(ptr[i], 0);
+ /* If it asserts once, it probably will 500,000 times */
+ if (ptr[i] != 0)
+ break;
+ }
+
+ buffer->ptr = old_ptr;
+ hmm_buffer_free(buffer);
+}
+
+/*
+ * Migrate private anonymous huge page and free.
+ */
+TEST_F(hmm, migrate_anon_huge_free)
+{
+ struct hmm_buffer *buffer;
+ unsigned long npages;
+ unsigned long size;
+ unsigned long i;
+ void *old_ptr;
+ void *map;
+ int *ptr;
+ int ret;
+
+ size = TWOMEG;
+
+ buffer = malloc(sizeof(*buffer));
+ ASSERT_NE(buffer, NULL);
+
+ buffer->fd = -1;
+ buffer->size = 2 * size;
+ buffer->mirror = malloc(size);
+ ASSERT_NE(buffer->mirror, NULL);
+ memset(buffer->mirror, 0xFF, size);
+
+ buffer->ptr = mmap(NULL, 2 * size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS,
+ buffer->fd, 0);
+ ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+ npages = size >> self->page_shift;
+ map = (void *)ALIGN((uintptr_t)buffer->ptr, size);
+ ret = madvise(map, size, MADV_HUGEPAGE);
+ ASSERT_EQ(ret, 0);
+ old_ptr = buffer->ptr;
+ buffer->ptr = map;
+
+ /* Initialize buffer in system memory. */
+ for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+ ptr[i] = i;
+
+ /* Migrate memory to device. */
+ ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+ ASSERT_EQ(ret, 0);
+ ASSERT_EQ(buffer->cpages, npages);
+
+ /* Check what the device read. */
+ for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+ ASSERT_EQ(ptr[i], i);
+
+ /* Try freeing it. */
+ ret = madvise(map, size, MADV_FREE);
+ ASSERT_EQ(ret, 0);
+
+ buffer->ptr = old_ptr;
+ hmm_buffer_free(buffer);
+}
+
+/*
+ * Migrate private anonymous huge page and fault back to sysmem.
+ */
+TEST_F(hmm, migrate_anon_huge_fault)
+{
+ struct hmm_buffer *buffer;
+ unsigned long npages;
+ unsigned long size;
+ unsigned long i;
+ void *old_ptr;
+ void *map;
+ int *ptr;
+ int ret;
+
+ size = TWOMEG;
+
+ buffer = malloc(sizeof(*buffer));
+ ASSERT_NE(buffer, NULL);
+
+ buffer->fd = -1;
+ buffer->size = 2 * size;
+ buffer->mirror = malloc(size);
+ ASSERT_NE(buffer->mirror, NULL);
+ memset(buffer->mirror, 0xFF, size);
+
+ buffer->ptr = mmap(NULL, 2 * size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS,
+ buffer->fd, 0);
+ ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+ npages = size >> self->page_shift;
+ map = (void *)ALIGN((uintptr_t)buffer->ptr, size);
+ ret = madvise(map, size, MADV_HUGEPAGE);
+ ASSERT_EQ(ret, 0);
+ old_ptr = buffer->ptr;
+ buffer->ptr = map;
+
+ /* Initialize buffer in system memory. */
+ for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+ ptr[i] = i;
+
+ /* Migrate memory to device. */
+ ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+ ASSERT_EQ(ret, 0);
+ ASSERT_EQ(buffer->cpages, npages);
+
+ /* Check what the device read. */
+ for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+ ASSERT_EQ(ptr[i], i);
+
+ /* Fault pages back to system memory and check them. */
+ for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+ ASSERT_EQ(ptr[i], i);
+
+ buffer->ptr = old_ptr;
+ hmm_buffer_free(buffer);
+}
+
+/*
+ * Migrate private anonymous huge page with allocation errors.
+ */
+TEST_F(hmm, migrate_anon_huge_err)
+{
+ struct hmm_buffer *buffer;
+ unsigned long npages;
+ unsigned long size;
+ unsigned long i;
+ void *old_ptr;
+ void *map;
+ int *ptr;
+ int ret;
+
+ size = TWOMEG;
+
+ buffer = malloc(sizeof(*buffer));
+ ASSERT_NE(buffer, NULL);
+
+ buffer->fd = -1;
+ buffer->size = 2 * size;
+ buffer->mirror = malloc(2 * size);
+ ASSERT_NE(buffer->mirror, NULL);
+ memset(buffer->mirror, 0xFF, 2 * size);
+
+ old_ptr = mmap(NULL, 2 * size, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, buffer->fd, 0);
+ ASSERT_NE(old_ptr, MAP_FAILED);
+
+ npages = size >> self->page_shift;
+ map = (void *)ALIGN((uintptr_t)old_ptr, size);
+ ret = madvise(map, size, MADV_HUGEPAGE);
+ ASSERT_EQ(ret, 0);
+ buffer->ptr = map;
+
+ /* Initialize buffer in system memory. */
+ for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+ ptr[i] = i;
+
+ /* Migrate memory to device but force a THP allocation error. */
+ ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_FLAGS, buffer,
+ HMM_DMIRROR_FLAG_FAIL_ALLOC);
+ ASSERT_EQ(ret, 0);
+ ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+ ASSERT_EQ(ret, 0);
+ ASSERT_EQ(buffer->cpages, npages);
+
+ /* Check what the device read. */
+ for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i) {
+ ASSERT_EQ(ptr[i], i);
+ if (ptr[i] != i)
+ break;
+ }
+
+ /* Try faulting back a single (PAGE_SIZE) page. */
+ ptr = buffer->ptr;
+ ASSERT_EQ(ptr[2048], 2048);
+
+ /* unmap and remap the region to reset things. */
+ ret = munmap(old_ptr, 2 * size);
+ ASSERT_EQ(ret, 0);
+ old_ptr = mmap(NULL, 2 * size, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, buffer->fd, 0);
+ ASSERT_NE(old_ptr, MAP_FAILED);
+ map = (void *)ALIGN((uintptr_t)old_ptr, size);
+ ret = madvise(map, size, MADV_HUGEPAGE);
+ ASSERT_EQ(ret, 0);
+ buffer->ptr = map;
+
+ /* Initialize buffer in system memory. */
+ for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+ ptr[i] = i;
+
+ /* Migrate THP to device. */
+ ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+ ASSERT_EQ(ret, 0);
+ ASSERT_EQ(buffer->cpages, npages);
+
+ /*
+ * Force an allocation error when faulting back a THP resident in the
+ * device.
+ */
+ ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_FLAGS, buffer,
+ HMM_DMIRROR_FLAG_FAIL_ALLOC);
+ ASSERT_EQ(ret, 0);
+
+ ret = hmm_migrate_dev_to_sys(self->fd, buffer, npages);
+ ASSERT_EQ(ret, 0);
+ ptr = buffer->ptr;
+ ASSERT_EQ(ptr[2048], 2048);
+
+ buffer->ptr = old_ptr;
+ hmm_buffer_free(buffer);
+}
+
+/*
+ * Migrate private anonymous huge zero page with allocation errors.
+ */
+TEST_F(hmm, migrate_anon_huge_zero_err)
+{
+ struct hmm_buffer *buffer;
+ unsigned long npages;
+ unsigned long size;
+ unsigned long i;
+ void *old_ptr;
+ void *map;
+ int *ptr;
+ int ret;
+
+ size = TWOMEG;
+
+ buffer = malloc(sizeof(*buffer));
+ ASSERT_NE(buffer, NULL);
+
+ buffer->fd = -1;
+ buffer->size = 2 * size;
+ buffer->mirror = malloc(2 * size);
+ ASSERT_NE(buffer->mirror, NULL);
+ memset(buffer->mirror, 0xFF, 2 * size);
+
+ old_ptr = mmap(NULL, 2 * size, PROT_READ,
+ MAP_PRIVATE | MAP_ANONYMOUS, buffer->fd, 0);
+ ASSERT_NE(old_ptr, MAP_FAILED);
+
+ npages = size >> self->page_shift;
+ map = (void *)ALIGN((uintptr_t)old_ptr, size);
+ ret = madvise(map, size, MADV_HUGEPAGE);
+ ASSERT_EQ(ret, 0);
+ buffer->ptr = map;
+
+ /* Migrate memory to device but force a THP allocation error. */
+ ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_FLAGS, buffer,
+ HMM_DMIRROR_FLAG_FAIL_ALLOC);
+ ASSERT_EQ(ret, 0);
+ ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+ ASSERT_EQ(ret, 0);
+ ASSERT_EQ(buffer->cpages, npages);
+
+ /* Check what the device read. */
+ for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+ ASSERT_EQ(ptr[i], 0);
+
+ /* Try faulting back a single (PAGE_SIZE) page. */
+ ptr = buffer->ptr;
+ ASSERT_EQ(ptr[2048], 0);
+
+ /* unmap and remap the region to reset things. */
+ ret = munmap(old_ptr, 2 * size);
+ ASSERT_EQ(ret, 0);
+ old_ptr = mmap(NULL, 2 * size, PROT_READ,
+ MAP_PRIVATE | MAP_ANONYMOUS, buffer->fd, 0);
+ ASSERT_NE(old_ptr, MAP_FAILED);
+ map = (void *)ALIGN((uintptr_t)old_ptr, size);
+ ret = madvise(map, size, MADV_HUGEPAGE);
+ ASSERT_EQ(ret, 0);
+ buffer->ptr = map;
+
+ /* Initialize buffer in system memory (zero THP page). */
+ ret = ptr[0];
+ ASSERT_EQ(ret, 0);
+
+ /* Migrate memory to device but force a THP allocation error. */
+ ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_FLAGS, buffer,
+ HMM_DMIRROR_FLAG_FAIL_ALLOC);
+ ASSERT_EQ(ret, 0);
+ ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+ ASSERT_EQ(ret, 0);
+ ASSERT_EQ(buffer->cpages, npages);
+
+ /* Fault the device memory back and check it. */
+ for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+ ASSERT_EQ(ptr[i], 0);
+
+ buffer->ptr = old_ptr;
+ hmm_buffer_free(buffer);
+}
TEST_HARNESS_MAIN
--
2.49.0
^ permalink raw reply related [flat|nested] 15+ messages in thread
* [v1 11/12] gpu/drm/nouveau: add THP migration support
2025-07-03 22:27 [v1 00/12] THP support for zone device page migration Balbir Singh
` (9 preceding siblings ...)
2025-07-03 22:27 ` [v1 10/12] selftests/mm/hmm-tests: new tests for zone device THP migration Balbir Singh
@ 2025-07-03 22:27 ` Balbir Singh
2025-07-03 22:27 ` [v1 12/12] selftests/mm/hmm-tests: new throughput tests including THP Balbir Singh
2025-07-03 23:00 ` [v1 00/12] THP support for zone device page migration Zi Yan
12 siblings, 0 replies; 15+ messages in thread
From: Balbir Singh @ 2025-07-03 22:27 UTC (permalink / raw)
To: linux-mm; +Cc: akpm, linux-kernel, Balbir Singh
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 <balbirs@nvidia.com>
---
drivers/gpu/drm/nouveau/nouveau_dmem.c | 246 +++++++++++++++++--------
drivers/gpu/drm/nouveau/nouveau_svm.c | 6 +-
drivers/gpu/drm/nouveau/nouveau_svm.h | 3 +-
3 files changed, 178 insertions(+), 77 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index ca4932a150e3..92b8877d8735 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -83,9 +83,15 @@ struct nouveau_dmem {
struct list_head chunks;
struct mutex mutex;
struct page *free_pages;
+ struct folio *free_folios;
spinlock_t lock;
};
+struct nouveau_dmem_dma_info {
+ dma_addr_t dma_addr;
+ size_t size;
+};
+
static struct nouveau_dmem_chunk *nouveau_page_to_chunk(struct page *page)
{
return container_of(page_pgmap(page), struct nouveau_dmem_chunk,
@@ -112,10 +118,16 @@ static void nouveau_dmem_page_free(struct page *page)
{
struct nouveau_dmem_chunk *chunk = nouveau_page_to_chunk(page);
struct nouveau_dmem *dmem = chunk->drm->dmem;
+ struct folio *folio = page_folio(page);
spin_lock(&dmem->lock);
- page->zone_device_data = dmem->free_pages;
- dmem->free_pages = page;
+ if (folio_order(folio)) {
+ folio_set_zone_device_data(folio, dmem->free_folios);
+ dmem->free_folios = folio;
+ } else {
+ page->zone_device_data = dmem->free_pages;
+ dmem->free_pages = page;
+ }
WARN_ON(!chunk->callocated);
chunk->callocated--;
@@ -139,20 +151,28 @@ static void nouveau_dmem_fence_done(struct nouveau_fence **fence)
}
}
-static int nouveau_dmem_copy_one(struct nouveau_drm *drm, struct page *spage,
- struct page *dpage, dma_addr_t *dma_addr)
+static int nouveau_dmem_copy_folio(struct nouveau_drm *drm,
+ struct folio *sfolio, struct folio *dfolio,
+ struct nouveau_dmem_dma_info *dma_info)
{
struct device *dev = drm->dev->dev;
+ struct page *dpage = folio_page(dfolio, 0);
+ struct page *spage = folio_page(sfolio, 0);
- lock_page(dpage);
+ folio_lock(dfolio);
- *dma_addr = dma_map_page(dev, dpage, 0, PAGE_SIZE, DMA_BIDIRECTIONAL);
- if (dma_mapping_error(dev, *dma_addr))
+ dma_info->dma_addr = dma_map_page(dev, dpage, 0, page_size(dpage),
+ DMA_BIDIRECTIONAL);
+ dma_info->size = page_size(dpage);
+ if (dma_mapping_error(dev, dma_info->dma_addr))
return -EIO;
- if (drm->dmem->migrate.copy_func(drm, 1, NOUVEAU_APER_HOST, *dma_addr,
- NOUVEAU_APER_VRAM, nouveau_dmem_page_addr(spage))) {
- dma_unmap_page(dev, *dma_addr, PAGE_SIZE, DMA_BIDIRECTIONAL);
+ if (drm->dmem->migrate.copy_func(drm, folio_nr_pages(sfolio),
+ NOUVEAU_APER_HOST, dma_info->dma_addr,
+ NOUVEAU_APER_VRAM,
+ nouveau_dmem_page_addr(spage))) {
+ dma_unmap_page(dev, dma_info->dma_addr, page_size(dpage),
+ DMA_BIDIRECTIONAL);
return -EIO;
}
@@ -165,21 +185,38 @@ static vm_fault_t nouveau_dmem_migrate_to_ram(struct vm_fault *vmf)
struct nouveau_dmem *dmem = drm->dmem;
struct nouveau_fence *fence;
struct nouveau_svmm *svmm;
- struct page *spage, *dpage;
- unsigned long src = 0, dst = 0;
- dma_addr_t dma_addr = 0;
+ struct page *dpage;
vm_fault_t ret = 0;
struct migrate_vma args = {
.vma = vmf->vma,
- .start = vmf->address,
- .end = vmf->address + PAGE_SIZE,
- .src = &src,
- .dst = &dst,
.pgmap_owner = drm->dev,
.fault_page = vmf->page,
- .flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE,
+ .flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE |
+ MIGRATE_VMA_SELECT_COMPOUND,
+ .src = NULL,
+ .dst = NULL,
};
-
+ unsigned int order, nr;
+ struct folio *sfolio, *dfolio;
+ struct nouveau_dmem_dma_info dma_info;
+
+ sfolio = page_folio(vmf->page);
+ order = folio_order(sfolio);
+ nr = 1 << order;
+
+ if (order)
+ args.flags |= MIGRATE_VMA_SELECT_COMPOUND;
+
+ args.start = ALIGN_DOWN(vmf->address, (1 << (PAGE_SHIFT + order)));
+ args.vma = vmf->vma;
+ args.end = args.start + (PAGE_SIZE << order);
+ args.src = kcalloc(nr, sizeof(*args.src), GFP_KERNEL);
+ args.dst = kcalloc(nr, sizeof(*args.dst), GFP_KERNEL);
+
+ if (!args.src || !args.dst) {
+ ret = VM_FAULT_OOM;
+ goto err;
+ }
/*
* FIXME what we really want is to find some heuristic to migrate more
* than just one page on CPU fault. When such fault happens it is very
@@ -190,20 +227,26 @@ static vm_fault_t nouveau_dmem_migrate_to_ram(struct vm_fault *vmf)
if (!args.cpages)
return 0;
- spage = migrate_pfn_to_page(src);
- if (!spage || !(src & MIGRATE_PFN_MIGRATE))
- goto done;
-
- dpage = alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO, vmf->vma, vmf->address);
- if (!dpage)
+ if (order)
+ dpage = folio_page(vma_alloc_folio(GFP_HIGHUSER | __GFP_ZERO,
+ order, vmf->vma, vmf->address), 0);
+ else
+ dpage = alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO, vmf->vma,
+ vmf->address);
+ if (!dpage) {
+ ret = VM_FAULT_OOM;
goto done;
+ }
- dst = migrate_pfn(page_to_pfn(dpage));
+ args.dst[0] = migrate_pfn(page_to_pfn(dpage));
+ if (order)
+ args.dst[0] |= MIGRATE_PFN_COMPOUND;
+ dfolio = page_folio(dpage);
- svmm = spage->zone_device_data;
+ svmm = folio_zone_device_data(sfolio);
mutex_lock(&svmm->mutex);
nouveau_svmm_invalidate(svmm, args.start, args.end);
- ret = nouveau_dmem_copy_one(drm, spage, dpage, &dma_addr);
+ ret = nouveau_dmem_copy_folio(drm, sfolio, dfolio, &dma_info);
mutex_unlock(&svmm->mutex);
if (ret) {
ret = VM_FAULT_SIGBUS;
@@ -213,19 +256,33 @@ static vm_fault_t nouveau_dmem_migrate_to_ram(struct vm_fault *vmf)
nouveau_fence_new(&fence, dmem->migrate.chan);
migrate_vma_pages(&args);
nouveau_dmem_fence_done(&fence);
- dma_unmap_page(drm->dev->dev, dma_addr, PAGE_SIZE, DMA_BIDIRECTIONAL);
+ dma_unmap_page(drm->dev->dev, dma_info.dma_addr, PAGE_SIZE,
+ DMA_BIDIRECTIONAL);
done:
migrate_vma_finalize(&args);
+err:
+ kfree(args.src);
+ kfree(args.dst);
return ret;
}
+static void nouveau_dmem_folio_split(struct folio *head, struct folio *tail)
+{
+ if (tail == NULL)
+ return;
+ tail->pgmap = head->pgmap;
+ folio_set_zone_device_data(tail, folio_zone_device_data(head));
+}
+
static const struct dev_pagemap_ops nouveau_dmem_pagemap_ops = {
.page_free = nouveau_dmem_page_free,
.migrate_to_ram = nouveau_dmem_migrate_to_ram,
+ .folio_split = nouveau_dmem_folio_split,
};
static int
-nouveau_dmem_chunk_alloc(struct nouveau_drm *drm, struct page **ppage)
+nouveau_dmem_chunk_alloc(struct nouveau_drm *drm, struct page **ppage,
+ bool is_large)
{
struct nouveau_dmem_chunk *chunk;
struct resource *res;
@@ -274,16 +331,21 @@ nouveau_dmem_chunk_alloc(struct nouveau_drm *drm, struct page **ppage)
pfn_first = chunk->pagemap.range.start >> PAGE_SHIFT;
page = pfn_to_page(pfn_first);
spin_lock(&drm->dmem->lock);
- for (i = 0; i < DMEM_CHUNK_NPAGES - 1; ++i, ++page) {
- page->zone_device_data = drm->dmem->free_pages;
- drm->dmem->free_pages = page;
+
+ if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) || !is_large) {
+ for (i = 0; i < DMEM_CHUNK_NPAGES - 1; ++i, ++page) {
+ page->zone_device_data = drm->dmem->free_pages;
+ drm->dmem->free_pages = page;
+ }
}
+
*ppage = page;
chunk->callocated++;
spin_unlock(&drm->dmem->lock);
- NV_INFO(drm, "DMEM: registered %ldMB of device memory\n",
- DMEM_CHUNK_SIZE >> 20);
+ NV_INFO(drm, "DMEM: registered %ldMB of %sdevice memory %lx %lx\n",
+ DMEM_CHUNK_SIZE >> 20, is_large ? "THP " : "", pfn_first,
+ nouveau_dmem_page_addr(page));
return 0;
@@ -298,27 +360,37 @@ nouveau_dmem_chunk_alloc(struct nouveau_drm *drm, struct page **ppage)
}
static struct page *
-nouveau_dmem_page_alloc_locked(struct nouveau_drm *drm)
+nouveau_dmem_page_alloc_locked(struct nouveau_drm *drm, bool is_large)
{
struct nouveau_dmem_chunk *chunk;
struct page *page = NULL;
+ struct folio *folio = NULL;
int ret;
+ unsigned int order = 0;
spin_lock(&drm->dmem->lock);
- if (drm->dmem->free_pages) {
+ if (is_large && drm->dmem->free_folios) {
+ folio = drm->dmem->free_folios;
+ drm->dmem->free_folios = folio_zone_device_data(folio);
+ chunk = nouveau_page_to_chunk(page);
+ chunk->callocated++;
+ spin_unlock(&drm->dmem->lock);
+ order = DMEM_CHUNK_NPAGES;
+ } else if (!is_large && drm->dmem->free_pages) {
page = drm->dmem->free_pages;
drm->dmem->free_pages = page->zone_device_data;
chunk = nouveau_page_to_chunk(page);
chunk->callocated++;
spin_unlock(&drm->dmem->lock);
+ folio = page_folio(page);
} else {
spin_unlock(&drm->dmem->lock);
- ret = nouveau_dmem_chunk_alloc(drm, &page);
+ ret = nouveau_dmem_chunk_alloc(drm, &page, is_large);
if (ret)
return NULL;
}
- zone_device_page_init(page);
+ init_zone_device_folio(folio, order);
return page;
}
@@ -369,12 +441,12 @@ nouveau_dmem_evict_chunk(struct nouveau_dmem_chunk *chunk)
{
unsigned long i, npages = range_len(&chunk->pagemap.range) >> PAGE_SHIFT;
unsigned long *src_pfns, *dst_pfns;
- dma_addr_t *dma_addrs;
+ struct nouveau_dmem_dma_info *dma_info;
struct nouveau_fence *fence;
src_pfns = kvcalloc(npages, sizeof(*src_pfns), GFP_KERNEL | __GFP_NOFAIL);
dst_pfns = kvcalloc(npages, sizeof(*dst_pfns), GFP_KERNEL | __GFP_NOFAIL);
- dma_addrs = kvcalloc(npages, sizeof(*dma_addrs), GFP_KERNEL | __GFP_NOFAIL);
+ dma_info = kvcalloc(npages, sizeof(*dma_info), GFP_KERNEL | __GFP_NOFAIL);
migrate_device_range(src_pfns, chunk->pagemap.range.start >> PAGE_SHIFT,
npages);
@@ -382,17 +454,28 @@ nouveau_dmem_evict_chunk(struct nouveau_dmem_chunk *chunk)
for (i = 0; i < npages; i++) {
if (src_pfns[i] & MIGRATE_PFN_MIGRATE) {
struct page *dpage;
+ struct folio *folio = page_folio(
+ migrate_pfn_to_page(src_pfns[i]));
+ unsigned int order = folio_order(folio);
+
+ if (src_pfns[i] & MIGRATE_PFN_COMPOUND) {
+ dpage = folio_page(
+ folio_alloc(
+ GFP_HIGHUSER_MOVABLE, order), 0);
+ } else {
+ /*
+ * _GFP_NOFAIL because the GPU is going away and there
+ * is nothing sensible we can do if we can't copy the
+ * data back.
+ */
+ dpage = alloc_page(GFP_HIGHUSER | __GFP_NOFAIL);
+ }
- /*
- * _GFP_NOFAIL because the GPU is going away and there
- * is nothing sensible we can do if we can't copy the
- * data back.
- */
- dpage = alloc_page(GFP_HIGHUSER | __GFP_NOFAIL);
dst_pfns[i] = migrate_pfn(page_to_pfn(dpage));
- nouveau_dmem_copy_one(chunk->drm,
- migrate_pfn_to_page(src_pfns[i]), dpage,
- &dma_addrs[i]);
+ nouveau_dmem_copy_folio(chunk->drm,
+ page_folio(migrate_pfn_to_page(src_pfns[i])),
+ page_folio(dpage),
+ &dma_info[i]);
}
}
@@ -403,8 +486,9 @@ nouveau_dmem_evict_chunk(struct nouveau_dmem_chunk *chunk)
kvfree(src_pfns);
kvfree(dst_pfns);
for (i = 0; i < npages; i++)
- dma_unmap_page(chunk->drm->dev->dev, dma_addrs[i], PAGE_SIZE, DMA_BIDIRECTIONAL);
- kvfree(dma_addrs);
+ dma_unmap_page(chunk->drm->dev->dev, dma_info[i].dma_addr,
+ dma_info[i].size, DMA_BIDIRECTIONAL);
+ kvfree(dma_info);
}
void
@@ -607,31 +691,35 @@ nouveau_dmem_init(struct nouveau_drm *drm)
static unsigned long nouveau_dmem_migrate_copy_one(struct nouveau_drm *drm,
struct nouveau_svmm *svmm, unsigned long src,
- dma_addr_t *dma_addr, u64 *pfn)
+ struct nouveau_dmem_dma_info *dma_info, u64 *pfn)
{
struct device *dev = drm->dev->dev;
struct page *dpage, *spage;
unsigned long paddr;
+ bool is_large = false;
spage = migrate_pfn_to_page(src);
if (!(src & MIGRATE_PFN_MIGRATE))
goto out;
- dpage = nouveau_dmem_page_alloc_locked(drm);
+ is_large = src & MIGRATE_PFN_COMPOUND;
+ dpage = nouveau_dmem_page_alloc_locked(drm, is_large);
if (!dpage)
goto out;
paddr = nouveau_dmem_page_addr(dpage);
if (spage) {
- *dma_addr = dma_map_page(dev, spage, 0, page_size(spage),
+ dma_info->dma_addr = dma_map_page(dev, spage, 0, page_size(spage),
DMA_BIDIRECTIONAL);
- if (dma_mapping_error(dev, *dma_addr))
+ dma_info->size = page_size(spage);
+ if (dma_mapping_error(dev, dma_info->dma_addr))
goto out_free_page;
- if (drm->dmem->migrate.copy_func(drm, 1,
- NOUVEAU_APER_VRAM, paddr, NOUVEAU_APER_HOST, *dma_addr))
+ if (drm->dmem->migrate.copy_func(drm, folio_nr_pages(page_folio(spage)),
+ NOUVEAU_APER_VRAM, paddr, NOUVEAU_APER_HOST,
+ dma_info->dma_addr))
goto out_dma_unmap;
} else {
- *dma_addr = DMA_MAPPING_ERROR;
+ dma_info->dma_addr = DMA_MAPPING_ERROR;
if (drm->dmem->migrate.clear_func(drm, page_size(dpage),
NOUVEAU_APER_VRAM, paddr))
goto out_free_page;
@@ -645,7 +733,7 @@ static unsigned long nouveau_dmem_migrate_copy_one(struct nouveau_drm *drm,
return migrate_pfn(page_to_pfn(dpage));
out_dma_unmap:
- dma_unmap_page(dev, *dma_addr, PAGE_SIZE, DMA_BIDIRECTIONAL);
+ dma_unmap_page(dev, dma_info->dma_addr, PAGE_SIZE, DMA_BIDIRECTIONAL);
out_free_page:
nouveau_dmem_page_free_locked(drm, dpage);
out:
@@ -655,27 +743,33 @@ static unsigned long nouveau_dmem_migrate_copy_one(struct nouveau_drm *drm,
static void nouveau_dmem_migrate_chunk(struct nouveau_drm *drm,
struct nouveau_svmm *svmm, struct migrate_vma *args,
- dma_addr_t *dma_addrs, u64 *pfns)
+ struct nouveau_dmem_dma_info *dma_info, u64 *pfns)
{
struct nouveau_fence *fence;
unsigned long addr = args->start, nr_dma = 0, i;
+ unsigned long order = 0;
- for (i = 0; addr < args->end; i++) {
+ for (i = 0; addr < args->end; ) {
+ struct folio *folio;
+
+ folio = page_folio(migrate_pfn_to_page(args->dst[i]));
+ order = folio_order(folio);
args->dst[i] = nouveau_dmem_migrate_copy_one(drm, svmm,
- args->src[i], dma_addrs + nr_dma, pfns + i);
- if (!dma_mapping_error(drm->dev->dev, dma_addrs[nr_dma]))
+ args->src[i], dma_info + nr_dma, pfns + i);
+ if (!dma_mapping_error(drm->dev->dev, dma_info[nr_dma].dma_addr))
nr_dma++;
- addr += PAGE_SIZE;
+ i += 1 << order;
+ addr += (1 << order) * PAGE_SIZE;
}
nouveau_fence_new(&fence, drm->dmem->migrate.chan);
migrate_vma_pages(args);
nouveau_dmem_fence_done(&fence);
- nouveau_pfns_map(svmm, args->vma->vm_mm, args->start, pfns, i);
+ nouveau_pfns_map(svmm, args->vma->vm_mm, args->start, pfns, i, order);
while (nr_dma--) {
- dma_unmap_page(drm->dev->dev, dma_addrs[nr_dma], PAGE_SIZE,
- DMA_BIDIRECTIONAL);
+ dma_unmap_page(drm->dev->dev, dma_info[nr_dma].dma_addr,
+ dma_info[nr_dma].size, DMA_BIDIRECTIONAL);
}
migrate_vma_finalize(args);
}
@@ -689,20 +783,24 @@ nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
{
unsigned long npages = (end - start) >> PAGE_SHIFT;
unsigned long max = min(SG_MAX_SINGLE_ALLOC, npages);
- dma_addr_t *dma_addrs;
struct migrate_vma args = {
.vma = vma,
.start = start,
.pgmap_owner = drm->dev,
- .flags = MIGRATE_VMA_SELECT_SYSTEM,
+ .flags = MIGRATE_VMA_SELECT_SYSTEM
+ | MIGRATE_VMA_SELECT_COMPOUND,
};
unsigned long i;
u64 *pfns;
int ret = -ENOMEM;
+ struct nouveau_dmem_dma_info *dma_info;
if (drm->dmem == NULL)
return -ENODEV;
+ if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
+ max = max(HPAGE_PMD_NR, max);
+
args.src = kcalloc(max, sizeof(*args.src), GFP_KERNEL);
if (!args.src)
goto out;
@@ -710,8 +808,8 @@ nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
if (!args.dst)
goto out_free_src;
- dma_addrs = kmalloc_array(max, sizeof(*dma_addrs), GFP_KERNEL);
- if (!dma_addrs)
+ dma_info = kmalloc_array(max, sizeof(*dma_info), GFP_KERNEL);
+ if (!dma_info)
goto out_free_dst;
pfns = nouveau_pfns_alloc(max);
@@ -729,7 +827,7 @@ nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
goto out_free_pfns;
if (args.cpages)
- nouveau_dmem_migrate_chunk(drm, svmm, &args, dma_addrs,
+ nouveau_dmem_migrate_chunk(drm, svmm, &args, dma_info,
pfns);
args.start = args.end;
}
@@ -738,7 +836,7 @@ nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
out_free_pfns:
nouveau_pfns_free(pfns);
out_free_dma:
- kfree(dma_addrs);
+ kfree(dma_info);
out_free_dst:
kfree(args.dst);
out_free_src:
diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
index 6fa387da0637..b8a3378154d5 100644
--- a/drivers/gpu/drm/nouveau/nouveau_svm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
@@ -921,12 +921,14 @@ nouveau_pfns_free(u64 *pfns)
void
nouveau_pfns_map(struct nouveau_svmm *svmm, struct mm_struct *mm,
- unsigned long addr, u64 *pfns, unsigned long npages)
+ unsigned long addr, u64 *pfns, unsigned long npages,
+ unsigned int page_shift)
{
struct nouveau_pfnmap_args *args = nouveau_pfns_to_args(pfns);
args->p.addr = addr;
- args->p.size = npages << PAGE_SHIFT;
+ args->p.size = npages << page_shift;
+ args->p.page = page_shift;
mutex_lock(&svmm->mutex);
diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.h b/drivers/gpu/drm/nouveau/nouveau_svm.h
index e7d63d7f0c2d..3fd78662f17e 100644
--- a/drivers/gpu/drm/nouveau/nouveau_svm.h
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.h
@@ -33,7 +33,8 @@ void nouveau_svmm_invalidate(struct nouveau_svmm *svmm, u64 start, u64 limit);
u64 *nouveau_pfns_alloc(unsigned long npages);
void nouveau_pfns_free(u64 *pfns);
void nouveau_pfns_map(struct nouveau_svmm *svmm, struct mm_struct *mm,
- unsigned long addr, u64 *pfns, unsigned long npages);
+ unsigned long addr, u64 *pfns, unsigned long npages,
+ unsigned int page_shift);
#else /* IS_ENABLED(CONFIG_DRM_NOUVEAU_SVM) */
static inline void nouveau_svm_init(struct nouveau_drm *drm) {}
static inline void nouveau_svm_fini(struct nouveau_drm *drm) {}
--
2.49.0
^ permalink raw reply related [flat|nested] 15+ messages in thread
* [v1 12/12] selftests/mm/hmm-tests: new throughput tests including THP
2025-07-03 22:27 [v1 00/12] THP support for zone device page migration Balbir Singh
` (10 preceding siblings ...)
2025-07-03 22:27 ` [v1 11/12] gpu/drm/nouveau: add THP migration support Balbir Singh
@ 2025-07-03 22:27 ` Balbir Singh
2025-07-03 23:00 ` [v1 00/12] THP support for zone device page migration Zi Yan
12 siblings, 0 replies; 15+ messages in thread
From: Balbir Singh @ 2025-07-03 22:27 UTC (permalink / raw)
To: linux-mm; +Cc: akpm, linux-kernel, Balbir Singh
Add new benchmark style support to test transfer bandwidth for
zone device memory operations.
Signed-off-by: Balbir Singh <balbirs@nvidia.com>
---
tools/testing/selftests/mm/hmm-tests.c | 197 ++++++++++++++++++++++++-
1 file changed, 196 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftests/mm/hmm-tests.c
index da3322a1282c..1325de70f44f 100644
--- a/tools/testing/selftests/mm/hmm-tests.c
+++ b/tools/testing/selftests/mm/hmm-tests.c
@@ -25,6 +25,7 @@
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
+#include <sys/time.h>
/*
@@ -207,8 +208,10 @@ static void hmm_buffer_free(struct hmm_buffer *buffer)
if (buffer == NULL)
return;
- if (buffer->ptr)
+ if (buffer->ptr) {
munmap(buffer->ptr, buffer->size);
+ buffer->ptr = NULL;
+ }
free(buffer->mirror);
free(buffer);
}
@@ -2466,4 +2469,196 @@ TEST_F(hmm, migrate_anon_huge_zero_err)
buffer->ptr = old_ptr;
hmm_buffer_free(buffer);
}
+
+struct benchmark_results {
+ double sys_to_dev_time;
+ double dev_to_sys_time;
+ double throughput_s2d;
+ double throughput_d2s;
+};
+
+static double get_time_ms(void)
+{
+ struct timeval tv;
+
+ gettimeofday(&tv, NULL);
+ return (tv.tv_sec * 1000.0) + (tv.tv_usec / 1000.0);
+}
+
+static inline struct hmm_buffer *hmm_buffer_alloc(unsigned long size)
+{
+ struct hmm_buffer *buffer;
+
+ buffer = malloc(sizeof(*buffer));
+
+ buffer->fd = -1;
+ buffer->size = size;
+ buffer->mirror = malloc(size);
+ memset(buffer->mirror, 0xFF, size);
+ return buffer;
+}
+
+static void print_benchmark_results(const char *test_name, size_t buffer_size,
+ struct benchmark_results *thp,
+ struct benchmark_results *regular)
+{
+ double s2d_improvement = ((regular->sys_to_dev_time - thp->sys_to_dev_time) /
+ regular->sys_to_dev_time) * 100.0;
+ double d2s_improvement = ((regular->dev_to_sys_time - thp->dev_to_sys_time) /
+ regular->dev_to_sys_time) * 100.0;
+ double throughput_s2d_improvement = ((thp->throughput_s2d - regular->throughput_s2d) /
+ regular->throughput_s2d) * 100.0;
+ double throughput_d2s_improvement = ((thp->throughput_d2s - regular->throughput_d2s) /
+ regular->throughput_d2s) * 100.0;
+
+ printf("\n=== %s (%.1f MB) ===\n", test_name, buffer_size / (1024.0 * 1024.0));
+ printf(" | With THP | Without THP | Improvement\n");
+ printf("---------------------------------------------------------------------\n");
+ printf("Sys->Dev Migration | %.3f ms | %.3f ms | %.1f%%\n",
+ thp->sys_to_dev_time, regular->sys_to_dev_time, s2d_improvement);
+ printf("Dev->Sys Migration | %.3f ms | %.3f ms | %.1f%%\n",
+ thp->dev_to_sys_time, regular->dev_to_sys_time, d2s_improvement);
+ printf("S->D Throughput | %.2f GB/s | %.2f GB/s | %.1f%%\n",
+ thp->throughput_s2d, regular->throughput_s2d, throughput_s2d_improvement);
+ printf("D->S Throughput | %.2f GB/s | %.2f GB/s | %.1f%%\n",
+ thp->throughput_d2s, regular->throughput_d2s, throughput_d2s_improvement);
+}
+
+/*
+ * Run a single migration benchmark
+ * fd: file descriptor for hmm device
+ * use_thp: whether to use THP
+ * buffer_size: size of buffer to allocate
+ * iterations: number of iterations
+ * results: where to store results
+ */
+static inline int run_migration_benchmark(int fd, int use_thp, size_t buffer_size,
+ int iterations, struct benchmark_results *results)
+{
+ struct hmm_buffer *buffer;
+ unsigned long npages = buffer_size / sysconf(_SC_PAGESIZE);
+ double start, end;
+ double s2d_total = 0, d2s_total = 0;
+ int ret, i;
+ int *ptr;
+
+ buffer = hmm_buffer_alloc(buffer_size);
+
+ /* Map memory */
+ buffer->ptr = mmap(NULL, buffer_size, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+ if (!buffer->ptr)
+ return -1;
+
+ /* Apply THP hint if requested */
+ if (use_thp)
+ ret = madvise(buffer->ptr, buffer_size, MADV_HUGEPAGE);
+ else
+ ret = madvise(buffer->ptr, buffer_size, MADV_NOHUGEPAGE);
+
+ if (ret)
+ return ret;
+
+ /* Initialize memory to make sure pages are allocated */
+ ptr = (int *)buffer->ptr;
+ for (i = 0; i < buffer_size / sizeof(int); i++)
+ ptr[i] = i & 0xFF;
+
+ /* Warmup iteration */
+ ret = hmm_migrate_sys_to_dev(fd, buffer, npages);
+ if (ret)
+ return ret;
+
+ ret = hmm_migrate_dev_to_sys(fd, buffer, npages);
+ if (ret)
+ return ret;
+
+ /* Benchmark iterations */
+ for (i = 0; i < iterations; i++) {
+ /* System to device migration */
+ start = get_time_ms();
+
+ ret = hmm_migrate_sys_to_dev(fd, buffer, npages);
+ if (ret)
+ return ret;
+
+ end = get_time_ms();
+ s2d_total += (end - start);
+
+ /* Device to system migration */
+ start = get_time_ms();
+
+ ret = hmm_migrate_dev_to_sys(fd, buffer, npages);
+ if (ret)
+ return ret;
+
+ end = get_time_ms();
+ d2s_total += (end - start);
+ }
+
+ /* Calculate average times and throughput */
+ results->sys_to_dev_time = s2d_total / iterations;
+ results->dev_to_sys_time = d2s_total / iterations;
+ results->throughput_s2d = (buffer_size / (1024.0 * 1024.0 * 1024.0)) /
+ (results->sys_to_dev_time / 1000.0);
+ results->throughput_d2s = (buffer_size / (1024.0 * 1024.0 * 1024.0)) /
+ (results->dev_to_sys_time / 1000.0);
+
+ /* Cleanup */
+ hmm_buffer_free(buffer);
+ return 0;
+}
+
+/*
+ * Benchmark THP migration with different buffer sizes
+ */
+TEST_F_TIMEOUT(hmm, benchmark_thp_migration, 120)
+{
+ struct benchmark_results thp_results, regular_results;
+ size_t thp_size = 2 * 1024 * 1024; /* 2MB - typical THP size */
+ int iterations = 5;
+
+ printf("\nHMM THP Migration Benchmark\n");
+ printf("---------------------------\n");
+ printf("System page size: %ld bytes\n", sysconf(_SC_PAGESIZE));
+
+ /* Test different buffer sizes */
+ size_t test_sizes[] = {
+ thp_size / 4, /* 512KB - smaller than THP */
+ thp_size / 2, /* 1MB - half THP */
+ thp_size, /* 2MB - single THP */
+ thp_size * 2, /* 4MB - two THPs */
+ thp_size * 4, /* 8MB - four THPs */
+ thp_size * 8, /* 16MB - eight THPs */
+ thp_size * 128, /* 256MB - one twenty eight THPs */
+ };
+
+ static const char *const test_names[] = {
+ "Small Buffer (512KB)",
+ "Half THP Size (1MB)",
+ "Single THP Size (2MB)",
+ "Two THP Size (4MB)",
+ "Four THP Size (8MB)",
+ "Eight THP Size (16MB)",
+ "One twenty eight THP Size (256MB)"
+ };
+
+ int num_tests = ARRAY_SIZE(test_sizes);
+
+ /* Run all tests */
+ for (int i = 0; i < num_tests; i++) {
+ /* Test with THP */
+ ASSERT_EQ(run_migration_benchmark(self->fd, 1, test_sizes[i],
+ iterations, &thp_results), 0);
+
+ /* Test without THP */
+ ASSERT_EQ(run_migration_benchmark(self->fd, 0, test_sizes[i],
+ iterations, ®ular_results), 0);
+
+ /* Print results */
+ print_benchmark_results(test_names[i], test_sizes[i],
+ &thp_results, ®ular_results);
+ }
+}
TEST_HARNESS_MAIN
--
2.49.0
^ permalink raw reply related [flat|nested] 15+ messages in thread
* Re: [v1 00/12] THP support for zone device page migration
2025-07-03 22:27 [v1 00/12] THP support for zone device page migration Balbir Singh
` (11 preceding siblings ...)
2025-07-03 22:27 ` [v1 12/12] selftests/mm/hmm-tests: new throughput tests including THP Balbir Singh
@ 2025-07-03 23:00 ` Zi Yan
2025-07-03 23:06 ` Balbir Singh
12 siblings, 1 reply; 15+ messages in thread
From: Zi Yan @ 2025-07-03 23:00 UTC (permalink / raw)
To: Balbir Singh
Cc: linux-mm, akpm, linux-kernel, Karol Herbst, Lyude Paul,
Danilo Krummrich, David Airlie, Simona Vetter,
Jérôme Glisse, Shuah Khan, David Hildenbrand,
Barry Song, Baolin Wang, Ryan Roberts, Matthew Wilcox, Peter Xu,
Kefeng Wang, Jane Chu, Alistair Popple, Donet Tom
On 3 Jul 2025, at 18:27, Balbir Singh wrote:
> This patch series adds support for THP migration of zone device pages.
> To do so, the patches implement support for folio zone device pages
> by adding support for setting up larger order pages.
>
> These patches build on the earlier posts by Ralph Campbell [1]
>
> Two new flags are added in vma_migration to select and mark compound pages.
> migrate_vma_setup(), migrate_vma_pages() and migrate_vma_finalize()
> support migration of these pages when MIGRATE_VMA_SELECT_COMPOUND
> is passed in as arguments.
>
> The series also adds zone device awareness to (m)THP pages along
> with fault handling of large zone device private pages. page vma walk
> and the rmap code is also zone device aware. Support has also been
> added for folios that might need to be split in the middle
> of migration (when the src and dst do not agree on
> MIGRATE_PFN_COMPOUND), that occurs when src side of the migration can
> migrate large pages, but the destination has not been able to allocate
> large pages. The code supported and used folio_split() when migrating
> THP pages, this is used when MIGRATE_VMA_SELECT_COMPOUND is not passed
> as an argument to migrate_vma_setup().
>
> The test infrastructure lib/test_hmm.c has been enhanced to support THP
> migration. A new ioctl to emulate failure of large page allocations has
> been added to test the folio split code path. hmm-tests.c has new test
> cases for huge page migration and to test the folio split path. A new
> throughput test has been added as well.
>
> The nouveau dmem code has been enhanced to use the new THP migration
> capability.
>
> Feedback from the RFC [2]:
>
> It was advised that prep_compound_page() not be exposed just for the purposes
> of testing (test driver lib/test_hmm.c). Work arounds of copy and split the
> folios did not work due to lock order dependency in the callback for
> split folio.
>
> mTHP support:
>
> The patches hard code, HPAGE_PMD_NR in a few places, but the code has
> been kept generic to support various order sizes. With additional
> refactoring of the code support of different order sizes should be
> possible.
>
> The future plan is to post enhancements to support mTHP with a rough
> design as follows:
>
> 1. Add the notion of allowable thp orders to the HMM based test driver
> 2. For non PMD based THP paths in migrate_device.c, check to see if
> a suitable order is found and supported by the driver
> 3. Iterate across orders to check the highest supported order for migration
> 4. Migrate and finalize
>
> The mTHP patches can be built on top of this series, the key design elements
> that need to be worked out are infrastructure and driver support for multiple
> ordered pages and their migration.
>
> References:
> [1] https://lore.kernel.org/linux-mm/20201106005147.20113-1-rcampbell@nvidia.com/
> [2] https://lore.kernel.org/linux-mm/20250306044239.3874247-3-balbirs@nvidia.com/T/
>
> These patches are built on top of mm-unstable
>
> Cc: Karol Herbst <kherbst@redhat.com>
> Cc: Lyude Paul <lyude@redhat.com>
> Cc: Danilo Krummrich <dakr@kernel.org>
> Cc: David Airlie <airlied@gmail.com>
> Cc: Simona Vetter <simona@ffwll.ch>
> Cc: "Jérôme Glisse" <jglisse@redhat.com>
> Cc: Shuah Khan <shuah@kernel.org>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Barry Song <baohua@kernel.org>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Ryan Roberts <ryan.roberts@arm.com>
> Cc: Matthew Wilcox <willy@infradead.org>
> Cc: Peter Xu <peterx@redhat.com>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
> Cc: Jane Chu <jane.chu@oracle.com>
> Cc: Alistair Popple <apopple@nvidia.com>
> Cc: Donet Tom <donettom@linux.ibm.com>
>
> Changelog v1:
> - Changes from RFC [2], include support for handling fault_folio and using
> trylock in the fault path
> - A new test case has been added to measure the throughput improvement
> - General refactoring of code to keep up with the changes in mm
> - New split folio callback when the entire split is complete/done. The
> callback is used to know when the head order needs to be reset.
>
> Testing:
> - Testing was done with ZONE_DEVICE private pages on an x86 VM
> - Throughput showed upto 5x improvement with THP migration, system to device
> migration is slower due to the mirroring of data (see buffer->mirror)
>
> Balbir Singh (12):
> 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 handling code
> mm/migrate_device: THP migration of zone device pages
> mm/memory/fault: Add support for zone device THP fault handling
> lib/test_hmm: test cases and support for zone device private THP
> mm/memremap: Add folio_split support
> mm/thp: add split during migration support
> lib/test_hmm: add test case for split pages
> selftests/mm/hmm-tests: new tests for zone device THP migration
> gpu/drm/nouveau: Add THP migration support
> selftests/mm/hmm-tests: New throughput tests including THP
>
> drivers/gpu/drm/nouveau/nouveau_dmem.c | 246 +++++---
> drivers/gpu/drm/nouveau/nouveau_svm.c | 6 +-
> drivers/gpu/drm/nouveau/nouveau_svm.h | 3 +-
> include/linux/huge_mm.h | 18 +-
> include/linux/memremap.h | 29 +-
> include/linux/migrate.h | 2 +
> include/linux/mm.h | 1 +
> lib/test_hmm.c | 428 ++++++++++---
> lib/test_hmm_uapi.h | 3 +
> mm/huge_memory.c | 261 ++++++--
> mm/memory.c | 6 +-
> mm/memremap.c | 50 +-
> mm/migrate.c | 2 +
> mm/migrate_device.c | 488 ++++++++++++---
> mm/page_alloc.c | 1 +
> mm/page_vma_mapped.c | 10 +
> mm/pgtable-generic.c | 6 +
> mm/rmap.c | 19 +-
> tools/testing/selftests/mm/hmm-tests.c | 805 ++++++++++++++++++++++++-
> 19 files changed, 2072 insertions(+), 312 deletions(-)
>
I only got the cover letter. Did you forget to send the actual patches?
Thanks.
Best Regards,
Yan, Zi
^ permalink raw reply [flat|nested] 15+ messages in thread
* Re: [v1 00/12] THP support for zone device page migration
2025-07-03 23:00 ` [v1 00/12] THP support for zone device page migration Zi Yan
@ 2025-07-03 23:06 ` Balbir Singh
0 siblings, 0 replies; 15+ messages in thread
From: Balbir Singh @ 2025-07-03 23:06 UTC (permalink / raw)
To: Zi Yan
Cc: linux-mm, akpm, linux-kernel, Karol Herbst, Lyude Paul,
Danilo Krummrich, David Airlie, Simona Vetter,
Jérôme Glisse, Shuah Khan, David Hildenbrand,
Barry Song, Baolin Wang, Ryan Roberts, Matthew Wilcox, Peter Xu,
Kefeng Wang, Jane Chu, Alistair Popple, Donet Tom
On 7/4/25 09:00, Zi Yan wrote:
> On 3 Jul 2025, at 18:27, Balbir Singh wrote:
>
>> This patch series adds support for THP migration of zone device pages.
>> To do so, the patches implement support for folio zone device pages
>> by adding support for setting up larger order pages.
>>
>> These patches build on the earlier posts by Ralph Campbell [1]
>>
>> Two new flags are added in vma_migration to select and mark compound pages.
>> migrate_vma_setup(), migrate_vma_pages() and migrate_vma_finalize()
>> support migration of these pages when MIGRATE_VMA_SELECT_COMPOUND
>> is passed in as arguments.
>>
>> The series also adds zone device awareness to (m)THP pages along
>> with fault handling of large zone device private pages. page vma walk
>> and the rmap code is also zone device aware. Support has also been
>> added for folios that might need to be split in the middle
>> of migration (when the src and dst do not agree on
>> MIGRATE_PFN_COMPOUND), that occurs when src side of the migration can
>> migrate large pages, but the destination has not been able to allocate
>> large pages. The code supported and used folio_split() when migrating
>> THP pages, this is used when MIGRATE_VMA_SELECT_COMPOUND is not passed
>> as an argument to migrate_vma_setup().
>>
>> The test infrastructure lib/test_hmm.c has been enhanced to support THP
>> migration. A new ioctl to emulate failure of large page allocations has
>> been added to test the folio split code path. hmm-tests.c has new test
>> cases for huge page migration and to test the folio split path. A new
>> throughput test has been added as well.
>>
>> The nouveau dmem code has been enhanced to use the new THP migration
>> capability.
>>
>> Feedback from the RFC [2]:
>>
>> It was advised that prep_compound_page() not be exposed just for the purposes
>> of testing (test driver lib/test_hmm.c). Work arounds of copy and split the
>> folios did not work due to lock order dependency in the callback for
>> split folio.
>>
>> mTHP support:
>>
>> The patches hard code, HPAGE_PMD_NR in a few places, but the code has
>> been kept generic to support various order sizes. With additional
>> refactoring of the code support of different order sizes should be
>> possible.
>>
>> The future plan is to post enhancements to support mTHP with a rough
>> design as follows:
>>
>> 1. Add the notion of allowable thp orders to the HMM based test driver
>> 2. For non PMD based THP paths in migrate_device.c, check to see if
>> a suitable order is found and supported by the driver
>> 3. Iterate across orders to check the highest supported order for migration
>> 4. Migrate and finalize
>>
>> The mTHP patches can be built on top of this series, the key design elements
>> that need to be worked out are infrastructure and driver support for multiple
>> ordered pages and their migration.
>>
>> References:
>> [1] https://lore.kernel.org/linux-mm/20201106005147.20113-1-rcampbell@nvidia.com/
>> [2] https://lore.kernel.org/linux-mm/20250306044239.3874247-3-balbirs@nvidia.com/T/
>>
>> These patches are built on top of mm-unstable
>>
>> Cc: Karol Herbst <kherbst@redhat.com>
>> Cc: Lyude Paul <lyude@redhat.com>
>> Cc: Danilo Krummrich <dakr@kernel.org>
>> Cc: David Airlie <airlied@gmail.com>
>> Cc: Simona Vetter <simona@ffwll.ch>
>> Cc: "Jérôme Glisse" <jglisse@redhat.com>
>> Cc: Shuah Khan <shuah@kernel.org>
>> Cc: David Hildenbrand <david@redhat.com>
>> Cc: Barry Song <baohua@kernel.org>
>> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
>> Cc: Ryan Roberts <ryan.roberts@arm.com>
>> Cc: Matthew Wilcox <willy@infradead.org>
>> Cc: Peter Xu <peterx@redhat.com>
>> Cc: Zi Yan <ziy@nvidia.com>
>> Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
>> Cc: Jane Chu <jane.chu@oracle.com>
>> Cc: Alistair Popple <apopple@nvidia.com>
>> Cc: Donet Tom <donettom@linux.ibm.com>
>>
>> Changelog v1:
>> - Changes from RFC [2], include support for handling fault_folio and using
>> trylock in the fault path
>> - A new test case has been added to measure the throughput improvement
>> - General refactoring of code to keep up with the changes in mm
>> - New split folio callback when the entire split is complete/done. The
>> callback is used to know when the head order needs to be reset.
>>
>> Testing:
>> - Testing was done with ZONE_DEVICE private pages on an x86 VM
>> - Throughput showed upto 5x improvement with THP migration, system to device
>> migration is slower due to the mirroring of data (see buffer->mirror)
>>
>> Balbir Singh (12):
>> 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 handling code
>> mm/migrate_device: THP migration of zone device pages
>> mm/memory/fault: Add support for zone device THP fault handling
>> lib/test_hmm: test cases and support for zone device private THP
>> mm/memremap: Add folio_split support
>> mm/thp: add split during migration support
>> lib/test_hmm: add test case for split pages
>> selftests/mm/hmm-tests: new tests for zone device THP migration
>> gpu/drm/nouveau: Add THP migration support
>> selftests/mm/hmm-tests: New throughput tests including THP
>>
>> drivers/gpu/drm/nouveau/nouveau_dmem.c | 246 +++++---
>> drivers/gpu/drm/nouveau/nouveau_svm.c | 6 +-
>> drivers/gpu/drm/nouveau/nouveau_svm.h | 3 +-
>> include/linux/huge_mm.h | 18 +-
>> include/linux/memremap.h | 29 +-
>> include/linux/migrate.h | 2 +
>> include/linux/mm.h | 1 +
>> lib/test_hmm.c | 428 ++++++++++---
>> lib/test_hmm_uapi.h | 3 +
>> mm/huge_memory.c | 261 ++++++--
>> mm/memory.c | 6 +-
>> mm/memremap.c | 50 +-
>> mm/migrate.c | 2 +
>> mm/migrate_device.c | 488 ++++++++++++---
>> mm/page_alloc.c | 1 +
>> mm/page_vma_mapped.c | 10 +
>> mm/pgtable-generic.c | 6 +
>> mm/rmap.c | 19 +-
>> tools/testing/selftests/mm/hmm-tests.c | 805 ++++++++++++++++++++++++-
>> 19 files changed, 2072 insertions(+), 312 deletions(-)
>>
>
> I only got the cover letter. Did you forget to send the actual patches?
>
A script of mine stripped the cc from the actual patches (my bad), the rest went to
linux-mm and linux-kernel. I can resend if needed
Balbir
^ permalink raw reply [flat|nested] 15+ messages in thread
end of thread, other threads:[~2025-07-03 23:06 UTC | newest]
Thread overview: 15+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-07-03 22:27 [v1 00/12] THP support for zone device page migration Balbir Singh
2025-07-03 22:27 ` [v1 01/12] mm/zone_device: support large zone device private folios Balbir Singh
2025-07-03 22:27 ` [v1 02/12] mm/migrate_device: flags for selecting device private THP pages Balbir Singh
2025-07-03 22:27 ` [v1 03/12] mm/thp: zone_device awareness in THP handling code Balbir Singh
2025-07-03 22:27 ` [v1 04/12] mm/migrate_device: THP migration of zone device pages Balbir Singh
2025-07-03 22:27 ` [v1 05/12] mm/memory/fault: add support for zone device THP fault handling Balbir Singh
2025-07-03 22:27 ` [v1 06/12] lib/test_hmm: test cases and support for zone device private THP Balbir Singh
2025-07-03 22:27 ` [v1 07/12] mm/memremap: add folio_split support Balbir Singh
2025-07-03 22:27 ` [v1 08/12] mm/thp: add split during migration support Balbir Singh
2025-07-03 22:27 ` [v1 09/12] lib/test_hmm: add test case for split pages Balbir Singh
2025-07-03 22:27 ` [v1 10/12] selftests/mm/hmm-tests: new tests for zone device THP migration Balbir Singh
2025-07-03 22:27 ` [v1 11/12] gpu/drm/nouveau: add THP migration support Balbir Singh
2025-07-03 22:27 ` [v1 12/12] selftests/mm/hmm-tests: new throughput tests including THP Balbir Singh
2025-07-03 23:00 ` [v1 00/12] THP support for zone device page migration Zi Yan
2025-07-03 23:06 ` Balbir Singh
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