[PATCH v2 10/14] mm/page-flags: introduce folio_test_fs_private()
From: Zi Yan <ziy@nvidia.com>
Date: 2026-08-31 19:26:16
Also in:
linux-fsdevel, linux-mm, lkml
Subsystem:
memory management, memory management - core, memory management - memory policy and migration, memory management - mglru (multi-gen lru), memory management - reclaim, memory management - thp (transparent huge page), page cache, the rest, tracing · Maintainers:
Andrew Morton, David Hildenbrand, Johannes Weiner, Matthew Wilcox, Jan Kara, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
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 <ziy@nvidia.com> To: Andrew Morton <akpm@linux-foundation.org> To: David Hildenbrand <david@kernel.org> To: Steven Rostedt <rostedt@goodmis.org> To: Masami Hiramatsu <mhiramat@kernel.org> To: Lorenzo Stoakes <ljs@kernel.org> Cc: "Liam R. Howlett" <liam@infradead.org> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Nico Pache <nico.pache@linux.dev> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Dev Jain <dev.jain@arm.com> Cc: Barry Song <baohua@kernel.org> Cc: Lance Yang <lance.yang@linux.dev> Cc: Usama Arif <usama.arif@linux.dev> Cc: Matthew Brost <matthew.brost@intel.com> Cc: Joshua Hahn <joshua.hahnjy@gmail.com> Cc: Rakie Kim <rakie.kim@sk.com> Cc: Byungchul Park <byungchul@sk.com> Cc: Gregory Price <gourry@gourry.net> Cc: Ying Huang <ying.huang@linux.alibaba.com> Cc: Alistair Popple <apopple@nvidia.com> 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 | 21 ++++++++++++++++++--- 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, 24 insertions(+), 20 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 786f8a47cea6d..b5b60f3ad58dc 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -3071,9 +3071,7 @@ 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_swapcache(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 ee7abb3000c11..9b585e68127a2 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h@@ -1210,6 +1210,23 @@ 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. + * + * 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_swapcache(folio) && + !folio_test_hugetlb(folio); +} /** * folio_has_private - Determine if folio has private stuff * @folio: The folio to be checked
@@ -1219,9 +1236,7 @@ static __always_inline void __ClearPageAnonExclusive(struct page *page) */ static inline int folio_has_private(const struct folio *folio) { - return (!!folio->private && !folio_test_swapcache(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 fb9abec40ec79..5425ef7bbae6e 100644
--- a/include/trace/events/pagemap.h
+++ b/include/trace/events/pagemap.h@@ -22,9 +22,7 @@ (folio_test_swapcache(folio) ? PAGEMAP_SWAPCACHE : 0) | \ (folio_test_swapbacked(folio) ? PAGEMAP_SWAPBACKED : 0) | \ (folio_test_mappedtodisk(folio) ? PAGEMAP_MAPPEDDISK : 0) | \ - (folio_test_private(folio) && \ - !folio_test_swapcache(folio) && \ - !folio_test_hugetlb(folio) ? PAGEMAP_BUFFERS : 0) \ + (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 546b37ccce37f..d085fd09466ef 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c@@ -4810,9 +4810,7 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start, * will try to drop it before split and then check if the folio * can be split or not. So skip the check here. */ - if (!(folio_test_private(folio) && - !folio_test_swapcache(folio) && - !folio_test_hugetlb(folio)) && + if (!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 f14e7bfee14bd..666a7365e16e8 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_swapcache(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 4022d6c381896..e03a1c46bce01 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c@@ -2705,10 +2705,7 @@ bool filemap_dirty_folio(struct address_space *mapping, struct folio *folio) if (folio_test_set_dirty(folio)) return false; - __folio_mark_dirty(folio, mapping, - !(folio_test_private(folio) && - !folio_test_swapcache(folio) && - !folio_test_hugetlb(folio))); + __folio_mark_dirty(folio, mapping, !folio_test_fs_private(folio)); if (mapping->host) { /* !PageAnon && !swapper_space */
diff --git a/mm/vmscan.c b/mm/vmscan.c
index ac275eec086b9..29051c0f89881 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c@@ -955,8 +955,7 @@ 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_swapcache(folio) && - !folio_test_hugetlb(folio))) + if (!folio_test_fs_private(folio)) return; mapping = folio_mapping(folio);
--
2.53.0