On 9/12/25 11:59, SeongJae Park wrote: > On Mon, 8 Sep 2025 10:04:36 +1000 Balbir Singh <[email protected]> wrote: > >> 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. >> >> Cc: Andrew Morton <[email protected]> >> Cc: David Hildenbrand <[email protected]> >> Cc: Zi Yan <[email protected]> >> Cc: Joshua Hahn <[email protected]> >> Cc: Rakie Kim <[email protected]> >> Cc: Byungchul Park <[email protected]> >> Cc: Gregory Price <[email protected]> >> Cc: Ying Huang <[email protected]> >> Cc: Alistair Popple <[email protected]> >> Cc: Oscar Salvador <[email protected]> >> Cc: Lorenzo Stoakes <[email protected]> >> Cc: Baolin Wang <[email protected]> >> Cc: "Liam R. Howlett" <[email protected]> >> Cc: Nico Pache <[email protected]> >> Cc: Ryan Roberts <[email protected]> >> Cc: Dev Jain <[email protected]> >> Cc: Barry Song <[email protected]> >> Cc: Lyude Paul <[email protected]> >> Cc: Danilo Krummrich <[email protected]> >> Cc: David Airlie <[email protected]> >> Cc: Simona Vetter <[email protected]> >> Cc: Ralph Campbell <[email protected]> >> Cc: Mika Penttilä <[email protected]> >> Cc: Matthew Brost <[email protected]> >> Cc: Francois Dugast <[email protected]> >> >> Signed-off-by: Balbir Singh <[email protected]> >> --- >> mm/damon/ops-common.c | 20 +++++++++++++++++--- >> mm/huge_memory.c | 16 +++++++++++++++- >> mm/page_idle.c | 5 +++-- >> mm/page_vma_mapped.c | 12 ++++++++++-- >> mm/rmap.c | 19 ++++++++++++++++--- >> 5 files changed, 61 insertions(+), 11 deletions(-) >> >> diff --git a/mm/damon/ops-common.c b/mm/damon/ops-common.c >> index 998c5180a603..eda4de553611 100644 >> --- a/mm/damon/ops-common.c >> +++ b/mm/damon/ops-common.c >> @@ -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 + PAGE_SIZE); >> + if (young) >> folio_set_young(folio); >> >> folio_set_idle(folio); >> @@ -203,7 +215,9 @@ 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); > > Could you please elaborate more about why the above change is needed on the > commit message? > > For example, I found below from v3 of this patch series: > > 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. > > Adding that kind of elaboration on the commit message would be helpful. > > Also, seems the DAMON part change is not really required to be made together > with other changes. If I'm not wrong, could you make DAMON part change as a > separate commit? > > The code looks good to me. > > Reviewed-by: SeongJae Park <[email protected]> > >
Thanks SJ! v3 had a separate flag during page vma mapped walk, so the walkers had to opt-in with a flag, I removed that after David's review feedback This change is required because we now support large folios in device private and hence the DAMON changes are included in this patch Balbir
