Commit 84a8d467 authored by Richard Weinberger's avatar Richard Weinberger Committed by Andrew Morton
Browse files

pagemap: update BUDDY flag documentation 

Since v4.6 the BUDDY flag is set for _all_ pages in the block
and no longer just for the first one.
This change was introduced by:
commit 832fc1de ("/proc/kpageflags: return KPF_BUDDY for "tail" buddy pages")

Strictly speaking, this was an ABI change, but as nobody has noticed
since 2016, let's just update the documentation.

Link: https://lkml.kernel.org/r/20251122211920.3410371-1-richard@nod.at


Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
Reviewed-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: default avatarDavid Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: default avatarMike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent b7dd80f8

Documentation/admin-guide/mm/pagemap.rst

+2 −1
Original line number Diff line number Diff line
@@ -115,7 +115,8 @@ Short descriptions to the page flags 
    A free memory block managed by the buddy system allocator.

    The buddy system organizes free memory in blocks of various orders.

    An order N block has 2^N physically contiguous pages, with the BUDDY flag

    set for and _only_ for the first page.

    set for all pages.

    Before 4.6 only the first page of the block had the flag set.

15 - COMPOUND_HEAD

    A compound page with order N consists of 2^N physically contiguous pages.

    A compound page with order 2 takes the form of "HTTT", where H donates its