On 2 Sep 2026, at 13:09, Usama Arif wrote: > On Mon, 31 Aug 2026 15:25:37 -0400 Zi Yan <[email protected]> wrote: > >> folio->private != NULL indicates a folio carries private data, replacing >> PG_private. All PG_private users are converted. Remove PG_private and >> reserve the space as __PG_folio for future use. >> >> Also update files in Documentation. hugetlbfs_reserv.rst is outdated and >> left unchanged. It should be rewritten. >> >> Assisted-by: Claude:claude-opus-4-8 >> Assisted-by: Codex:gpt-5 >> Signed-off-by: Zi Yan <[email protected]> >> To: Andrew Morton <[email protected]> >> To: Baoquan He <[email protected]> >> To: Mike Rapoport <[email protected]> >> To: Pasha Tatashin <[email protected]> >> To: Pratyush Yadav <[email protected]> >> To: Jonathan Corbet <[email protected]> >> To: "Matthew Wilcox (Oracle)" <[email protected]> >> To: Jan Kara <[email protected]> >> To: David Hildenbrand <[email protected]> >> To: Steven Rostedt <[email protected]> >> To: Masami Hiramatsu <[email protected]> >> Cc: Dave Young <[email protected]> >> Cc: Shuah Khan <[email protected]> >> Cc: Lorenzo Stoakes <[email protected]> >> Cc: "Liam R. Howlett" <[email protected]> >> Cc: Vlastimil Babka <[email protected]> >> Cc: Suren Baghdasaryan <[email protected]> >> Cc: Michal Hocko <[email protected]> >> Cc: Mathieu Desnoyers <[email protected]> >> Cc: [email protected] >> Cc: [email protected] >> Cc: [email protected] >> Cc: [email protected] >> Cc: [email protected] >> Cc: [email protected] >> --- >> Documentation/admin-guide/kdump/vmcoreinfo.rst | 2 +- >> Documentation/filesystems/vfs.rst | 6 +++--- >> include/linux/page-flags.h | 19 ++----------------- >> include/trace/events/mmflags.h | 2 +- >> kernel/vmcore_info.c | 1 - >> 5 files changed, 7 insertions(+), 23 deletions(-) >> >> diff --git a/Documentation/admin-guide/kdump/vmcoreinfo.rst >> b/Documentation/admin-guide/kdump/vmcoreinfo.rst >> index 7663c610fe901..5f1df6d080508 100644 >> --- a/Documentation/admin-guide/kdump/vmcoreinfo.rst >> +++ b/Documentation/admin-guide/kdump/vmcoreinfo.rst >> @@ -325,7 +325,7 @@ NR_FREE_PAGES >> On linux-2.6.21 or later, the number of free pages is in >> vm_stat[NR_FREE_PAGES]. Used to get the number of free pages. >> >> -PG_lru|PG_private|PG_swapcache|PG_swapbacked|PG_hwpoison|PG_head_mask >> +PG_lru|PG_swapcache|PG_swapbacked|PG_hwpoison|PG_head_mask >> -------------------------------------------------------------------------- >> >> Page attributes. These flags are used to filter various unnecessary for >> diff --git a/Documentation/filesystems/vfs.rst >> b/Documentation/filesystems/vfs.rst >> index d3a93eec3945f..dec7816303c6a 100644 >> --- a/Documentation/filesystems/vfs.rst >> +++ b/Documentation/filesystems/vfs.rst >> @@ -649,8 +649,8 @@ Writeback. >> >> The first can be used independently to the others. The VM can try to >> release clean pages in order to reuse them. To do this it can call >> -->release_folio on clean folios with the private >> -flag set. Clean pages without PagePrivate and with no external references >> +->release_folio on clean folios with folio->private set. Clean pages >> +without folio->private set and with no external references >> will be released without notice being given to the address_space. >> >> To achieve this functionality, pages need to be placed on an LRU with >> @@ -674,7 +674,7 @@ filemap_fdatawait_range, to wait for all writeback to >> complete. >> >> An address_space handler may attach extra information to a page, >> typically using the 'private' field in the 'struct page'. If such >> -information is attached, the PG_Private flag should be set. This will >> +information is attached, non-NULL 'private' field will >> cause various VM routines to make extra calls into the address_space >> handler to deal with that data. >> >> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h >> index 9b585e68127a2..eb2961ed61018 100644 >> --- a/include/linux/page-flags.h >> +++ b/include/linux/page-flags.h >> @@ -44,10 +44,6 @@ >> * Consequently, PG_reserved for a page mapped into user space can indicate >> * the zero page, the vDSO, MMIO pages or device memory. >> * >> - * The PG_private bitflag is set on pagecache pages if they contain >> filesystem >> - * specific data (which is normally at page->private). It can be used by >> - * private allocations for its own usage. >> - * >> * During initiation of disk I/O, PG_locked is set. This bit is set before >> I/O >> * and cleared when writeback _starts_ or when read _completes_. >> PG_writeback >> * is set before writeback starts and cleared when it finishes. >> @@ -105,7 +101,7 @@ enum pageflags { >> PG_owner_2, /* Owner use. If pagecache, fs may use */ >> PG_arch_1, >> PG_reserved, >> - PG_private, /* If pagecache, has fs-private data */ >> + __PG_folio, /* Do not use: reserved for folio >> identification */ >> PG_private_2, /* If pagecache, has fs aux data */ >> PG_reclaim, /* To be reclaimed asap */ >> PG_swapbacked, /* Page is backed by RAM/swap */ >> @@ -576,7 +572,7 @@ FOLIO_FLAG(swapbacked, FOLIO_HEAD_PAGE) >> /* >> * Private page markings that may be used by the filesystem that owns the >> page >> * for its own purposes. >> - * - PG_private and PG_private_2 cause release_folio() and co to be invoked >> + * - folio->private and PG_private_2 cause release_folio() and co to be >> invoked >> */ >> >> static __always_inline bool folio_test_private(const struct folio *folio) >> @@ -584,17 +580,6 @@ 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 */ >> diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h >> index 935893e5ea53b..caf090cd6f85e 100644 >> --- a/include/trace/events/mmflags.h >> +++ b/include/trace/events/mmflags.h >> @@ -144,7 +144,7 @@ TRACE_DEFINE_ENUM(___GFP_LAST_BIT); >> DEF_PAGEFLAG_NAME(owner_2), \ >> DEF_PAGEFLAG_NAME(arch_1), \ >> DEF_PAGEFLAG_NAME(reserved), \ >> - DEF_PAGEFLAG_NAME(private), \ >> + { 1UL << __PG_folio, "folio" }, \ >> DEF_PAGEFLAG_NAME(private_2), \ >> DEF_PAGEFLAG_NAME(writeback), \ >> DEF_PAGEFLAG_NAME(head), \ >> diff --git a/kernel/vmcore_info.c b/kernel/vmcore_info.c >> index 8614430ca212a..5a417f8a922ab 100644 >> --- a/kernel/vmcore_info.c >> +++ b/kernel/vmcore_info.c >> @@ -216,7 +216,6 @@ static int __init crash_save_vmcoreinfo_init(void) >> VMCOREINFO_LENGTH(free_area.free_list, MIGRATE_TYPES); >> VMCOREINFO_NUMBER(NR_FREE_PAGES); >> VMCOREINFO_NUMBER(PG_lru); >> - VMCOREINFO_NUMBER(PG_private); >> VMCOREINFO_NUMBER(PG_swapcache); >> VMCOREINFO_NUMBER(PG_swapbacked); >> #define PAGE_SLAB_MAPCOUNT_VALUE (PGTY_slab << 24) > > + kdump maintainers and reviewers.
Thanks. > > I believe makedumpfile reads VMCOREINFO. Removing it here, might cause issues > for older makedumpfile versions at crashdump? The expectation is that kdump userspace tools will adapt to this change. Later, PG_folio will be added to identify folios and has the same value of PG_private, so preserving PG_private will not work then. > > Hopefully kdump folks will be able to comment better. Best Regards, Yan, Zi
