From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0C37F2609E3 for ; Mon, 21 Sep 2026 03:31:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789961501; cv=none; b=tuCgeiaC/rUTHRIdGoJdMrhCjk4Cmzt/DO7Bkah4H6c5MjuBy136k3qiouUkB8rXrlflcLe0a8tZisJYKOLE3Z7EK2lA8RP1udb5tn2MOo719zLZ+9q7Ao3YuFlE/OZSMPMH6ISYOiUyyRPuJOFx1c0/ZsH9KhSol+Fio+ss2rc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789961501; c=relaxed/simple; bh=3dINcsqTb/hivQdjInNZEdBo5mmwUVNVZbfuX4RjyjQ=; h=Date:To:From:Subject:Message-Id; b=bT9HBsPVJChJBqohqx6DgYM6VqGidAwmysFQZmT0mj1wJyXIR0eUpOkKXcYsgyoJTyJB81z0F47qgvKgZ7eI9awigfa6Z5Dw224OdUT3RIC8RVh2bzEbD6WG7pmug3WMzH1giT4bxXZtkRP+5GCDTtbfpmnDWjc4FRRaXSWVfZM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=od7uToNl; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="od7uToNl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D3DA51F000FF; Mon, 21 Sep 2026 03:31:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1789961499; bh=4Bo7/2tE3nxdBlbIq5NUG8+mokZvzEqniyYjKTTpd2k=; h=Date:To:From:Subject; b=od7uToNl8p0+14NomRoz8/c1V4wjtW0n8X7P3vc8DVcesMlP5mUOne4v29tljlP+C /kf8Ei+lpVICWOw/bwQAPkUN7FlooJ6vMgZ7kq8w3M6hbuB6FzoRCEK5qhZXSh8Dwi jUnW7lp8rO8yiwtCNX7BJb/NSiOMu2uHEL/uJBYc= Date: Sun, 20 Sep 2026 20:31:39 -0700 To: mm-commits@vger.kernel.org,ziy@nvidia.com,akpm@linux-foundation.org From: Andrew Morton Subject: [to-be-updated] mm-page-flags-check-page-folio-private-instead-of-pg_private.patch removed from -mm tree Message-Id: <20260921033139.D3DA51F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm/page-flags: check page/folio->private instead of PG_private has been removed from the -mm tree. Its filename was mm-page-flags-check-page-folio-private-instead-of-pg_private.patch This patch was dropped because an updated version will be issued ------------------------------------------------------ From: Zi Yan Subject: mm/page-flags: check page/folio->private instead of PG_private Date: Sun, 13 Sep 2026 22:24:08 -0400 After the changes of the prior commits, page/folio->private != NULL is now equivalent to checking PG_private. Stop checking PG_private on pages and folios and use page/folio->private instead, except swapcache and hugetlb folios, because the former uses a field (swp_entry_t swap) overlapping with ->private and the latter sets its flags in ->private. Exclude swapcache and hugetlb when the code is meant to check PG_private only. PG_swapcache and folio->swap.val cannot be set/clear as a whole, so excluding swapcache with folio_test_swapcache() is not reliable. Instead, use folio_test_swapbacked(), since PG_swapbacked is stable when a folio is added to/removed from swapcache. Add a helper, folio_has_attached_private(), for this check. folio_expected_ref_count() can be called without folio lock, so annotate folio_test_private() with data_race() to avoid triggering race condition checks. While at it, annotate folio->mapping too. Add data_race() annotation for other lockless callers too. folio_set/clear_private() and Set/ClearPagePrivate() become no-ops. PG_private is no longer checked at page free time. Remove KPF_PRIVATE since PG_private is no longer used. Assisted-by: LLM Link: https://lore.kernel.org/20260913-remove-pg_private-v4-10-848550f7574e@nvidia.com Signed-off-by: Zi Yan Signed-off-by: Andrew Morton Cc: David Hildenbrand Cc: Steven Rostedt Cc: Masami Hiramatsu Cc: Lorenzo Stoakes Cc: "Matthew Wilcox (Oracle)" Cc: Jan Kara Cc: Johannes Weiner Cc: "Liam R. Howlett" Cc: Vlastimil Babka Cc: Mike Rapoport Cc: Suren Baghdasaryan Cc: Michal Hocko Cc: Mathieu Desnoyers 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: Qi Zheng Cc: Shakeel Butt Cc: Kairui Song Cc: Axel Rasmussen Cc: Yuanchu Xie Cc: Wei Xu --- fs/proc/page.c | 1 include/linux/kernel-page-flags.h | 1 include/linux/mm.h | 20 +++++++----- include/linux/page-flags.h | 46 ++++++++++++++++++++++++---- include/trace/events/pagemap.h | 3 + mm/huge_memory.c | 3 + mm/migrate.c | 2 - mm/page-writeback.c | 3 + mm/vmscan.c | 2 - tools/mm/page-types.c | 2 - 10 files changed, 62 insertions(+), 21 deletions(-) --- a/fs/proc/page.c~mm-page-flags-check-page-folio-private-instead-of-pg_private +++ a/fs/proc/page.c @@ -232,7 +232,6 @@ u64 stable_page_flags(const struct page u |= kpf_copy_bit(k, KPF_RESERVED, PG_reserved); u |= kpf_copy_bit(k, KPF_OWNER_2, PG_owner_2); - u |= kpf_copy_bit(k, KPF_PRIVATE, PG_private); u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2); u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1); u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1); --- a/include/linux/kernel-page-flags.h~mm-page-flags-check-page-folio-private-instead-of-pg_private +++ a/include/linux/kernel-page-flags.h @@ -11,7 +11,6 @@ #define KPF_RESERVED 32 #define KPF_MLOCKED 33 #define KPF_OWNER_2 34 -#define KPF_PRIVATE 35 #define KPF_PRIVATE_2 36 #define KPF_OWNER_PRIVATE 37 #define KPF_ARCH 38 --- a/include/linux/mm.h~mm-page-flags-check-page-folio-private-instead-of-pg_private +++ a/include/linux/mm.h @@ -3004,9 +3004,9 @@ static inline bool folio_maybe_mapped_sh * @folio: the folio * * Calculate the expected folio refcount, taking references from the pagecache, - * swapcache, PG_private and page table mappings into account. Useful in - * combination with folio_ref_count() to detect unexpected references (e.g., - * GUP or other temporary references). + * swapcache, private data (folio->private != NULL) and page table mappings into + * account. Useful in combination with folio_ref_count() to detect unexpected + * references (e.g., GUP or other temporary references). * * Does currently not consider references from the LRU cache. If the folio * was isolated from the LRU (which is the case during migration or split), @@ -3044,10 +3044,16 @@ static inline int folio_expected_ref_cou ref_count += folio_test_swapcache(folio) << order; if (!folio_test_anon(folio)) { - /* One reference per page from the pagecache. */ - ref_count += !!folio->mapping << order; - /* One reference from PG_private. */ - ref_count += folio_test_private(folio); + /* + * One reference per page from the pagecache. + * Use data_race() since folio might not be locked. + */ + ref_count += !!data_race(folio->mapping) << order; + /* + * One reference from filesystem private data. + * Use data_race() since folio might not be locked. + */ + ref_count += data_race(folio_has_attached_private(folio)); } /* One reference per page table mapping. */ --- a/include/linux/page-flags.h~mm-page-flags-check-page-folio-private-instead-of-pg_private +++ a/include/linux/page-flags.h @@ -577,7 +577,23 @@ FOLIO_FLAG(swapbacked, FOLIO_HEAD_PAGE) * for its own purposes. * - PG_private and PG_private_2 cause release_folio() and co to be invoked */ -PAGEFLAG(Private, private, PF_ANY) + +static __always_inline bool folio_test_private(const struct folio *folio) +{ + return folio->private; +} + +static __always_inline int PagePrivate(const struct page *page) +{ + return !!page->private; +} + +/* no-ops during transition */ +static __always_inline void folio_set_private(struct folio *folio) { } +static __always_inline void folio_clear_private(struct folio *folio) { } +static __always_inline void SetPagePrivate(struct page *page) { } +static __always_inline void ClearPagePrivate(struct page *page) { } + FOLIO_FLAG(private_2, FOLIO_HEAD_PAGE) /* owner_2 can be set on tail pages for anon memory */ @@ -1169,7 +1185,7 @@ static __always_inline void __ClearPageA */ #define PAGE_FLAGS_CHECK_AT_FREE \ (1UL << PG_lru | 1UL << PG_locked | \ - 1UL << PG_private | 1UL << PG_private_2 | \ + 1UL << PG_private_2 | \ 1UL << PG_writeback | 1UL << PG_reserved | \ 1UL << PG_active | \ 1UL << PG_unevictable | __PG_MLOCKED | LRU_GEN_MASK) @@ -1193,8 +1209,28 @@ static __always_inline void __ClearPageA (0xffUL /* order */ | 1UL << PG_has_hwpoisoned | \ 1UL << PG_large_rmappable | 1UL << PG_partially_mapped) -#define PAGE_FLAGS_PRIVATE \ - (1UL << PG_private | 1UL << PG_private_2) +/** + * folio_has_attached_private - check if the folio has private data attached + * @folio: The folio to check. + * + * Use this in code that may encounter swapcache or hugetlb folios but only + * wants to detect attached 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_has_attached_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 @@ -1204,7 +1240,7 @@ static __always_inline void __ClearPageA */ static inline int folio_has_private(const struct folio *folio) { - return !!(folio->flags.f & PAGE_FLAGS_PRIVATE); + return folio_has_attached_private(folio) || folio_test_private_2(folio); } #undef PF_ANY --- a/include/trace/events/pagemap.h~mm-page-flags-check-page-folio-private-instead-of-pg_private +++ a/include/trace/events/pagemap.h @@ -22,7 +22,8 @@ (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) ? PAGEMAP_BUFFERS : 0) \ + /* data_race() is used to read attached private locklessly */ \ + (data_race(folio_has_attached_private(folio)) ? PAGEMAP_BUFFERS : 0) \ ) TRACE_EVENT(mm_lru_insertion, --- a/mm/huge_memory.c~mm-page-flags-check-page-folio-private-instead-of-pg_private +++ a/mm/huge_memory.c @@ -4845,8 +4845,9 @@ static int split_huge_pages_pid(int pid, * For folios with private, split_huge_page_to_list_to_order() * will try to drop it before split and then check if the folio * can be split or not. So skip the check here. + * data_race() is used to read attached private locklessly. */ - if (!folio_test_private(folio) && + if (!data_race(folio_has_attached_private(folio)) && folio_expected_ref_count(folio) != folio_ref_count(folio)) goto next; --- a/mm/migrate.c~mm-page-flags-check-page-folio-private-instead-of-pg_private +++ a/mm/migrate.c @@ -1327,7 +1327,7 @@ static int migrate_folio_unmap(new_folio * free the metadata, so the page can be freed. */ if (!src->mapping) { - if (folio_test_private(src)) { + if (folio_has_attached_private(src)) { try_to_free_buffers(src); goto out; } --- a/mm/page-writeback.c~mm-page-flags-check-page-folio-private-instead-of-pg_private +++ a/mm/page-writeback.c @@ -2705,7 +2705,8 @@ bool filemap_dirty_folio(struct address_ if (folio_test_set_dirty(folio)) return false; - __folio_mark_dirty(folio, mapping, !folio_test_private(folio)); + /* data_race() is used to read attached private locklessly */ + __folio_mark_dirty(folio, mapping, !data_race(folio_has_attached_private(folio))); if (mapping->host) { /* !PageAnon && !swapper_space */ --- a/mm/vmscan.c~mm-page-flags-check-page-folio-private-instead-of-pg_private +++ a/mm/vmscan.c @@ -1029,7 +1029,7 @@ static void folio_check_dirty_writeback( *writeback = folio_test_writeback(folio); /* Verify dirty/writeback state if the filesystem supports it */ - if (!folio_test_private(folio)) + if (!folio_has_attached_private(folio)) return; mapping = folio_mapping(folio); --- a/tools/mm/page-types.c~mm-page-flags-check-page-folio-private-instead-of-pg_private +++ a/tools/mm/page-types.c @@ -73,7 +73,6 @@ #define KPF_RESERVED 32 #define KPF_MLOCKED 33 #define KPF_OWNER_2 34 -#define KPF_PRIVATE 35 #define KPF_PRIVATE_2 36 #define KPF_OWNER_PRIVATE 37 #define KPF_ARCH 38 @@ -131,7 +130,6 @@ static const char * const page_flag_name [KPF_RESERVED] = "r:reserved", [KPF_MLOCKED] = "m:mlocked", [KPF_OWNER_2] = "d:owner_2", - [KPF_PRIVATE] = "P:private", [KPF_PRIVATE_2] = "p:private_2", [KPF_OWNER_PRIVATE] = "O:owner_private", [KPF_ARCH] = "h:arch", _ Patches currently in -mm which might be from ziy@nvidia.com are treewide-remove-folio_set-clear_private-usage.patch ceph-replace-pageprivate-with-page_private.patch md-md-bitmap-replace-pageprivate-with-page_private.patch buffer-replace-page_buffer-with-page_private-and-delete-it.patch treewide-remove-pageprivate-and-pg_private-from-comments-and-docs.patch mm-page-flags-remove-pg_private.patch usb-gadgetfs-do-not-warn-about-excessively-large-memory-allocations.patch