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mm/rmap: extend rmap and migration support device-private entries 

Add device-private THP support to reverse mapping infrastructure, enabling
proper handling during migration and walk operations.

The key changes are:
- add_migration_pmd()/remove_migration_pmd(): Handle device-private
  entries during folio migration and splitting
- page_vma_mapped_walk(): Recognize device-private THP entries during
  VMA traversal operations

This change supports folio splitting and migration operations on
device-private entries.

[balbirs@nvidia.com: fix override of entry in remove_migration_pmd]
  Link: https://lkml.kernel.org/r/20251114012153.2634497-2-balbirs@nvidia.com
[balbirs@nvidia.com: follow pattern used in remove_migration_pte()]
  Link: https://lkml.kernel.org/r/20251115002835.3515194-1-balbirs@nvidia.com
Link: https://lkml.kernel.org/r/20251001065707.920170-5-balbirs@nvidia.com
Signed-off-by: Balbir Singh <balbirs@nvidia.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Ying Huang <ying.huang@linux.alibaba.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Barry Song <baohua@kernel.org>
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: Ralph Campbell <rcampbell@nvidia.com>
Cc: Mika Penttilä <mpenttil@redhat.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Francois Dugast <francois.dugast@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Balbir Singh 2025-10-01 16:56:55 +10:00 committed by Andrew Morton
parent 368076f52e
commit 65edfda6f3
5 changed files with 71 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
mm/damon/ops-common.c
View File

@ -75,12 +75,24 @@ void damon_ptep_mkold(pte_t *pte, struct vm_area_struct *vma, unsigned long addr
void damon_pmdp_mkold(pmd_t *pmd, struct vm_area_struct *vma, unsigned long addr)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
struct folio *folio = damon_get_folio(pmd_pfn(pmdp_get(pmd)));
pmd_t pmdval = pmdp_get(pmd);
struct folio *folio;
bool young = false;
unsigned long pfn;
if (likely(pmd_present(pmdval)))
pfn = pmd_pfn(pmdval);
else
pfn = swp_offset_pfn(pmd_to_swp_entry(pmdval));
folio = damon_get_folio(pfn);
if (!folio)
return;
if (pmdp_clear_young_notify(vma, addr, pmd))
if (likely(pmd_present(pmdval)))
young |= pmdp_clear_young_notify(vma, addr, pmd);
young |= mmu_notifier_clear_young(vma->vm_mm, addr, addr + HPAGE_PMD_SIZE);
if (young)
folio_set_young(folio);
folio_set_idle(folio);
@ -199,7 +211,9 @@ static bool damon_folio_young_one(struct folio *folio,
mmu_notifier_test_young(vma->vm_mm, addr);
} else {
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
*accessed = pmd_young(pmdp_get(pvmw.pmd)) ||
pmd_t pmd = pmdp_get(pvmw.pmd);
*accessed = (pmd_present(pmd) && pmd_young(pmd)) ||
!folio_test_idle(folio) ||
mmu_notifier_test_young(vma->vm_mm, addr);
#else

23
mm/huge_memory.c
View File

@ -4583,7 +4583,10 @@ 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 (unlikely(!pmd_present(*pvmw->pmd)))
pmdval = pmdp_huge_get_and_clear(vma->vm_mm, address, pvmw->pmd);
else
pmdval = pmdp_invalidate(vma, address, pvmw->pmd);
/* See folio_try_share_anon_rmap_pmd(): invalidate PMD first. */
anon_exclusive = folio_test_anon(folio) && PageAnonExclusive(page);
@ -4633,6 +4636,7 @@ 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 (pmd_swp_soft_dirty(*pvmw->pmd))
pmde = pmd_mksoft_dirty(pmde);
if (is_writable_migration_entry(entry))
@ -4645,6 +4649,23 @@ void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
if (folio_test_dirty(folio) && is_migration_entry_dirty(entry))
pmde = pmd_mkdirty(pmde);
if (folio_is_device_private(folio)) {
swp_entry_t entry;
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_swp_mksoft_dirty(pmde);
if (pmd_swp_uffd_wp(*pvmw->pmd))
pmde = pmd_swp_mkuffd_wp(pmde);
}
if (folio_test_anon(folio)) {
rmap_t rmap_flags = RMAP_NONE;

7
mm/page_idle.c
View File

@ -71,8 +71,11 @@ static bool page_idle_clear_pte_refs_one(struct folio *folio,
referenced |= ptep_test_and_clear_young(vma, addr, pvmw.pte);
referenced |= mmu_notifier_clear_young(vma->vm_mm, addr, addr + PAGE_SIZE);
} else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
if (pmdp_clear_young_notify(vma, addr, pvmw.pmd))
referenced = true;
pmd_t pmdval = pmdp_get(pvmw.pmd);
if (likely(pmd_present(pmdval)))
referenced |= pmdp_clear_young_notify(vma, addr, pvmw.pmd);
referenced |= mmu_notifier_clear_young(vma->vm_mm, addr, addr + PMD_SIZE);
} else {
/* unexpected pmd-mapped page? */
WARN_ON_ONCE(1);

7
mm/page_vma_mapped.c
View File

@ -277,6 +277,13 @@ 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 = 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) &&

24
mm/rmap.c
View File

@ -1022,9 +1022,16 @@ static int page_vma_mkclean_one(struct page_vma_mapped_walk *pvmw)
} else {
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
pmd_t *pmd = pvmw->pmd;
pmd_t entry;
pmd_t entry = pmdp_get(pmd);
if (!pmd_dirty(*pmd) && !pmd_write(*pmd))
/*
* Please see the comment above (!pte_present).
* A non present PMD is not writable from a CPU
* perspective.
*/
if (!pmd_present(entry))
continue;
if (!pmd_dirty(entry) && !pmd_write(entry))
continue;
flush_cache_range(vma, address,
@ -2319,6 +2326,9 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
while (page_vma_mapped_walk(&pvmw)) {
/* PMD-mapped THP migration entry */
if (!pvmw.pte) {
__maybe_unused unsigned long pfn;
__maybe_unused pmd_t pmdval;
if (flags & TTU_SPLIT_HUGE_PMD) {
split_huge_pmd_locked(vma, pvmw.address,
pvmw.pmd, true);
@ -2327,8 +2337,14 @@ 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));
pmdval = pmdp_get(pvmw.pmd);
if (likely(pmd_present(pmdval)))
pfn = pmd_pfn(pmdval);
else
pfn = swp_offset_pfn(pmd_to_swp_entry(pmdval));
subpage = folio_page(folio, pfn - folio_pfn(folio));
VM_BUG_ON_FOLIO(folio_test_hugetlb(folio) ||
!folio_test_pmd_mappable(folio), folio);