• Rik van Riel's avatar
    rmap: add exclusively owned pages to the newest anon_vma · e8a03feb
    Rik van Riel authored
    The recent anon_vma fixes cause many anonymous pages to end up
    in the parent process anon_vma, even when the page is exclusively
    owned by the current process.
    
    Adding exclusively owned anonymous pages to the top anon_vma
    reduces rmap scanning overhead, especially in workloads with
    forking servers.
    
    This patch adds a parameter to __page_set_anon_rmap that can
    be used to indicate whether or not the added page is exclusively
    owned by the current process.
    
    Pages added through page_add_new_anon_rmap are exclusively
    owned by the current process, and can be added to the top
    anon_vma.
    
    Pages added through page_add_anon_rmap can be either shared
    or exclusively owned, so we do the conservative thing and
    add it to the oldest anon_vma.
    
    A next step would be to add the exclusive parameter to
    page_add_anon_rmap, to be used from functions where we do
    know for sure whether a page is exclusively owned.
    Signed-off-by: default avatarRik van Riel <riel@redhat.com>
    Reviewed-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
    Lightly-tested-by: default avatarBorislav Petkov <bp@alien8.de>
    Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
    [ Edited to look nicer  - Linus ]
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    e8a03feb
rmap.c 40.1 KB