diff options
| -rw-r--r-- | mm/rmap.c | 87 |
1 files changed, 48 insertions, 39 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 9cb496d7b375..dd1309d72e37 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2068,6 +2068,50 @@ range_end: return ret; } +static bool ttu_anon_lazyfree_folio(struct vm_area_struct *vma, + struct folio *folio, unsigned long nr_pages) +{ + int ref_count, map_count; + + /* + * Synchronize with gup_pte_range(): + * - clear PTE; barrier; read refcount + * - inc refcount; barrier; read PTE + */ + smp_mb(); + + ref_count = folio_ref_count(folio); + map_count = folio_mapcount(folio); + + /* + * Order reads for page refcount and dirty flag + * (see comments in __remove_mapping()). + */ + smp_rmb(); + + if (folio_test_dirty(folio) && !(vma->vm_flags & VM_DROPPABLE)) { + /* + * redirtied either using the page table or a previously + * obtained GUP reference. + */ + folio_set_swapbacked(folio); + return false; + } + + /* + * Additional references could be due to GUP or speculative lookups. + * GUP users must mark the folio dirty if there was a modification. + * This folio cannot be reclaimed right now either way, so act just + * like nothing happened. We'll come back here later and detect if the + * folio was dirtied when the additional reference is gone. + */ + if (ref_count != 1 + map_count) + return false; + + add_mm_counter(vma->vm_mm, MM_ANONPAGES, -nr_pages); + return true; +} + /* * @arg: enum ttu_flags will be passed to this argument */ @@ -2261,47 +2305,12 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, /* MADV_FREE page check */ if (!folio_test_swapbacked(folio)) { - int ref_count, map_count; - - /* - * Synchronize with gup_pte_range(): - * - clear PTE; barrier; read refcount - * - inc refcount; barrier; read PTE - */ - smp_mb(); - - ref_count = folio_ref_count(folio); - map_count = folio_mapcount(folio); - - /* - * Order reads for page refcount and dirty flag - * (see comments in __remove_mapping()). - */ - smp_rmb(); - - if (folio_test_dirty(folio) && !(vma->vm_flags & VM_DROPPABLE)) { - /* - * redirtied either using the page table or a previously - * obtained GUP reference. - */ - set_ptes(mm, address, pvmw.pte, pteval, nr_pages); - folio_set_swapbacked(folio); - goto walk_abort; - } else if (ref_count != 1 + map_count) { - /* - * Additional reference. Could be a GUP reference or any - * speculative reference. GUP users must mark the folio - * dirty if there was a modification. This folio cannot be - * reclaimed right now either way, so act just like nothing - * happened. - * We'll come back here later and detect if the folio was - * dirtied when the additional reference is gone. - */ + if (!ttu_anon_lazyfree_folio(vma, folio, + nr_pages)) { set_ptes(mm, address, pvmw.pte, pteval, nr_pages); goto walk_abort; } - add_mm_counter(mm, MM_ANONPAGES, -nr_pages); - goto discard; + goto finish_unmap; } if (folio_dup_swap(folio, subpage) < 0) { @@ -2359,7 +2368,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, */ add_mm_counter(mm, mm_counter_file(folio), -nr_pages); } -discard: +finish_unmap: folio_remove_rmap_ptes(folio, subpage, nr_pages, vma); if (vma->vm_flags & VM_LOCKED) mlock_drain_local(); |