folio_test_fs_private() wraps folio->private != NULL check and excludes swapcache and hugetlb folios, since swapcache uses swp_entry_t overlapping with folio->private and hugetlb sets its own flags in folio->private. Replace open code with the helper, since core MM does this check frequently. No functional change intended. Assisted-by: Claude:claude-opus-4-8 Assisted-by: Codex:gpt-5 Signed-off-by: Zi Yan To: Andrew Morton To: David Hildenbrand To: Steven Rostedt To: Masami Hiramatsu To: Lorenzo Stoakes Cc: "Liam R. Howlett" Cc: Vlastimil Babka Cc: Mike Rapoport Cc: Suren Baghdasaryan Cc: Michal Hocko Cc: Mathieu Desnoyers Cc: Zi Yan Cc: Baolin Wang Cc: Nico Pache Cc: Ryan Roberts Cc: Dev Jain Cc: Barry Song Cc: Lance Yang Cc: Usama Arif Cc: Matthew Brost Cc: Joshua Hahn Cc: Rakie Kim Cc: Byungchul Park Cc: Gregory Price Cc: Ying Huang Cc: Alistair Popple Cc: linux-kernel@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org Cc: linux-mm@kvack.org Cc: linux-trace-kernel@vger.kernel.org --- include/linux/mm.h | 4 +--- include/linux/page-flags.h | 26 +++++++++++++++++++++++--- include/trace/events/pagemap.h | 4 +--- mm/huge_memory.c | 4 +--- mm/migrate.c | 3 +-- mm/page-writeback.c | 5 +---- mm/vmscan.c | 3 +-- 7 files changed, 29 insertions(+), 20 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 5eb8a62fafb56..c861525cda83f 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3053,9 +3053,7 @@ static inline int folio_expected_ref_count(const struct folio *folio) * One reference from filesystem private data. * Use data_race() since folio might not be locked. */ - ref_count += data_race(folio_test_private(folio)) && - !folio_test_hugetlb(folio) && - !folio_test_swapbacked(folio); + ref_count += data_race(folio_test_fs_private(folio)); } /* One reference per page table mapping. */ diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 9cb4d64739798..ce7fccd90367b 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -1210,6 +1210,28 @@ static __always_inline void __ClearPageAnonExclusive(struct page *page) (0xffUL /* order */ | 1UL << PG_has_hwpoisoned | \ 1UL << PG_large_rmappable | 1UL << PG_partially_mapped) +/** + * folio_test_fs_private - check if the folio has filesystem private data + * @folio: The folio to check. + * + * Use this in code that may encounter swapcache or hugetlb folios but only + * wants to detect filesystem private data. Swapcache stores swp_entry_t in + * folio->swap, a union with folio->private, and hugetlb stores its own flags + * in folio->private; both are excluded. + * + * NOTE: For swapcache, folio->swap.val PG_swapcache are not set as a whole, + * so folio_test_swapcache() is not reliable to exclude swapcache. + * Use folio_test_swapbacked() instead, since it remains set when a folio is + * added to/removed from swapcache. + * + * Return: true if folio->private is set and the folio is neither swapcache + * nor hugetlb. + */ +static inline bool folio_test_fs_private(const struct folio *folio) +{ + return folio_test_private(folio) && !folio_test_swapbacked(folio) && + !folio_test_hugetlb(folio); +} /** * folio_has_private - Determine if folio has private stuff * @folio: The folio to be checked @@ -1219,9 +1241,7 @@ static __always_inline void __ClearPageAnonExclusive(struct page *page) */ static inline int folio_has_private(const struct folio *folio) { - return (!!folio->private && !folio_test_swapbacked(folio) && - !folio_test_hugetlb(folio)) || - folio_test_private_2(folio); + return folio_test_fs_private(folio) || folio_test_private_2(folio); } #undef PF_ANY diff --git a/include/trace/events/pagemap.h b/include/trace/events/pagemap.h index 8193f91216822..547a550b81ee1 100644 --- a/include/trace/events/pagemap.h +++ b/include/trace/events/pagemap.h @@ -23,9 +23,7 @@ (folio_test_swapbacked(folio) ? PAGEMAP_SWAPBACKED : 0) | \ (folio_test_mappedtodisk(folio) ? PAGEMAP_MAPPEDDISK : 0) | \ /* data_race() is used to read folio->private locklessly */ \ - (data_race(folio_test_private(folio)) && \ - !folio_test_swapbacked(folio) && \ - !folio_test_hugetlb(folio) ? PAGEMAP_BUFFERS : 0) \ + (data_race(folio_test_fs_private(folio)) ? PAGEMAP_BUFFERS : 0) \ ) TRACE_EVENT(mm_lru_insertion, diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 9b2a9d0794a61..4cb7d9bc47544 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -4833,9 +4833,7 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start, * can be split or not. So skip the check here. * data_race() is used to read folio->private locklessly. */ - if (!(data_race(folio_test_private(folio)) && - !folio_test_swapbacked(folio) && - !folio_test_hugetlb(folio)) && + if (!data_race(folio_test_fs_private(folio)) && folio_expected_ref_count(folio) != folio_ref_count(folio)) goto next; diff --git a/mm/migrate.c b/mm/migrate.c index f6befd3ff1c46..2e133d533c8da 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1327,8 +1327,7 @@ static int migrate_folio_unmap(new_folio_t get_new_folio, * free the metadata, so the page can be freed. */ if (!src->mapping) { - if (folio_test_private(src) && !folio_test_swapbacked(src) && - !folio_test_hugetlb(src)) { + if (folio_test_fs_private(src)) { try_to_free_buffers(src); goto out; } diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 02ad49b10be07..e7389020d2a56 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -2706,10 +2706,7 @@ bool filemap_dirty_folio(struct address_space *mapping, struct folio *folio) return false; /* data_race() is used to read folio->private locklessly */ - __folio_mark_dirty(folio, mapping, - !(data_race(folio_test_private(folio)) && - !folio_test_swapbacked(folio) && - !folio_test_hugetlb(folio))); + __folio_mark_dirty(folio, mapping, !data_race(folio_test_fs_private(folio))); if (mapping->host) { /* !PageAnon && !swapper_space */ diff --git a/mm/vmscan.c b/mm/vmscan.c index 9348ebf9de882..47352bafc5b6f 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -978,8 +978,7 @@ static void folio_check_dirty_writeback(struct folio *folio, *writeback = folio_test_writeback(folio); /* Verify dirty/writeback state if the filesystem supports it */ - if (!(folio_test_private(folio) && !folio_test_swapbacked(folio) && - !folio_test_hugetlb(folio))) + if (!folio_test_fs_private(folio)) return; mapping = folio_mapping(folio); -- 2.53.0