diff options
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 21 |
1 files changed, 18 insertions, 3 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 8616308610b9..2490e727e2dc 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1412,7 +1412,11 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma, VM_BUG_ON_VMA(address < vma->vm_start || address + (nr << PAGE_SHIFT) > vma->vm_end, vma); - if (!folio_test_swapbacked(folio)) + /* + * VM_DROPPABLE mappings don't swap; instead they're just dropped when + * under memory pressure. + */ + if (!folio_test_swapbacked(folio) && !(vma->vm_flags & VM_DROPPABLE)) __folio_set_swapbacked(folio); __folio_set_anon(folio, vma, address, exclusive); @@ -1848,7 +1852,13 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, * plus the rmap(s) (dropped by discard:). */ if (ref_count == 1 + map_count && - !folio_test_dirty(folio)) { + (!folio_test_dirty(folio) || + /* + * Unlike MADV_FREE mappings, VM_DROPPABLE + * ones can be dropped even if they've + * been dirtied. + */ + (vma->vm_flags & VM_DROPPABLE))) { dec_mm_counter(mm, MM_ANONPAGES); goto discard; } @@ -1858,7 +1868,12 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, * discarded. Remap the page to page table. */ set_pte_at(mm, address, pvmw.pte, pteval); - folio_set_swapbacked(folio); + /* + * Unlike MADV_FREE mappings, VM_DROPPABLE ones + * never get swap backed on failure to drop. + */ + if (!(vma->vm_flags & VM_DROPPABLE)) + folio_set_swapbacked(folio); goto walk_abort; } |