6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Usama Arif <usamaarif642@xxxxxxxxx> commit 42b2eb69835b0fda797f70eb5b4fc213dbe3a7ea upstream. Other page flags in the 2nd page, like PG_hwpoison and PG_anon_exclusive can get modified concurrently. Changes to other page flags might be lost if they are happening at the same time as non-atomic partially_mapped operations. Hence, make partially_mapped operations atomic. Link: https://lkml.kernel.org/r/20241212183351.1345389-1-usamaarif642@xxxxxxxxx Fixes: 8422acdc97ed ("mm: introduce a pageflag for partially mapped folios") Reported-by: David Hildenbrand <david@xxxxxxxxxx> Link: https://lore.kernel.org/all/e53b04ad-1827-43a2-a1ab-864c7efecf6e@xxxxxxxxxx/ Signed-off-by: Usama Arif <usamaarif642@xxxxxxxxx> Acked-by: David Hildenbrand <david@xxxxxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Acked-by: Roman Gushchin <roman.gushchin@xxxxxxxxx> Cc: Barry Song <baohua@xxxxxxxxxx> Cc: Domenico Cerasuolo <cerasuolodomenico@xxxxxxxxx> Cc: Jonathan Corbet <corbet@xxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx> Cc: Nico Pache <npache@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxxx> Cc: Ryan Roberts <ryan.roberts@xxxxxxx> Cc: Shakeel Butt <shakeel.butt@xxxxxxxxx> Cc: Yu Zhao <yuzhao@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- include/linux/page-flags.h | 12 ++---------- mm/huge_memory.c | 8 ++++---- 2 files changed, 6 insertions(+), 14 deletions(-) --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -860,18 +860,10 @@ static inline void ClearPageCompound(str ClearPageHead(page); } FOLIO_FLAG(large_rmappable, FOLIO_SECOND_PAGE) -FOLIO_TEST_FLAG(partially_mapped, FOLIO_SECOND_PAGE) -/* - * PG_partially_mapped is protected by deferred_split split_queue_lock, - * so its safe to use non-atomic set/clear. - */ -__FOLIO_SET_FLAG(partially_mapped, FOLIO_SECOND_PAGE) -__FOLIO_CLEAR_FLAG(partially_mapped, FOLIO_SECOND_PAGE) +FOLIO_FLAG(partially_mapped, FOLIO_SECOND_PAGE) #else FOLIO_FLAG_FALSE(large_rmappable) -FOLIO_TEST_FLAG_FALSE(partially_mapped) -__FOLIO_SET_FLAG_NOOP(partially_mapped) -__FOLIO_CLEAR_FLAG_NOOP(partially_mapped) +FOLIO_FLAG_FALSE(partially_mapped) #endif #define PG_head_mask ((1UL << PG_head)) --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3503,7 +3503,7 @@ int split_huge_page_to_list_to_order(str !list_empty(&folio->_deferred_list)) { ds_queue->split_queue_len--; if (folio_test_partially_mapped(folio)) { - __folio_clear_partially_mapped(folio); + folio_clear_partially_mapped(folio); mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); } @@ -3615,7 +3615,7 @@ bool __folio_unqueue_deferred_split(stru if (!list_empty(&folio->_deferred_list)) { ds_queue->split_queue_len--; if (folio_test_partially_mapped(folio)) { - __folio_clear_partially_mapped(folio); + folio_clear_partially_mapped(folio); mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); } @@ -3659,7 +3659,7 @@ void deferred_split_folio(struct folio * spin_lock_irqsave(&ds_queue->split_queue_lock, flags); if (partially_mapped) { if (!folio_test_partially_mapped(folio)) { - __folio_set_partially_mapped(folio); + folio_set_partially_mapped(folio); if (folio_test_pmd_mappable(folio)) count_vm_event(THP_DEFERRED_SPLIT_PAGE); count_mthp_stat(folio_order(folio), MTHP_STAT_SPLIT_DEFERRED); @@ -3752,7 +3752,7 @@ static unsigned long deferred_split_scan } else { /* We lost race with folio_put() */ if (folio_test_partially_mapped(folio)) { - __folio_clear_partially_mapped(folio); + folio_clear_partially_mapped(folio); mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); }
