• Joel Fernandes (Google)'s avatar
    mm: treewide: remove unused address argument from pte_alloc functions · 4cf58924
    Joel Fernandes (Google) authored
    Patch series "Add support for fast mremap".
    
    This series speeds up the mremap(2) syscall by copying page tables at
    the PMD level even for non-THP systems.  There is concern that the extra
    'address' argument that mremap passes to pte_alloc may do something
    subtle architecture related in the future that may make the scheme not
    work.  Also we find that there is no point in passing the 'address' to
    pte_alloc since its unused.  This patch therefore removes this argument
    tree-wide resulting in a nice negative diff as well.  Also ensuring
    along the way that the enabled architectures do not do anything funky
    with the 'address' argument that goes unnoticed by the optimization.
    
    Build and boot tested on x86-64.  Build tested on arm64.  The config
    enablement patch for arm64 will be posted in the future after more
    testing.
    
    The changes were obtained by applying the following Coccinelle script.
    (thanks Julia for answering all Coccinelle questions!).
    Following fix ups were done manually:
    * Removal of address argument from  pte_fragment_alloc
    * Removal of pte_alloc_one_fast definitions from m68k and microblaze.
    
    // Options: --include-headers --no-includes
    // Note: I split the 'identifier fn' line, so if you are manually
    // running it, please unsplit it so it runs for you.
    
    virtual patch
    
    @pte_alloc_func_def depends on patch exists@
    identifier E2;
    identifier fn =~
    "^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
    type T2;
    @@
    
     fn(...
    - , T2 E2
     )
     { ... }
    
    @pte_alloc_func_proto_noarg depends on patch exists@
    type T1, T2, T3, T4;
    identifier fn =~ "^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
    @@
    
    (
    - T3 fn(T1, T2);
    + T3 fn(T1);
    |
    - T3 fn(T1, T2, T4);
    + T3 fn(T1, T2);
    )
    
    @pte_alloc_func_proto depends on patch exists@
    identifier E1, E2, E4;
    type T1, T2, T3, T4;
    identifier fn =~
    "^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
    @@
    
    (
    - T3 fn(T1 E1, T2 E2);
    + T3 fn(T1 E1);
    |
    - T3 fn(T1 E1, T2 E2, T4 E4);
    + T3 fn(T1 E1, T2 E2);
    )
    
    @pte_alloc_func_call depends on patch exists@
    expression E2;
    identifier fn =~
    "^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
    @@
    
     fn(...
    -,  E2
     )
    
    @pte_alloc_macro depends on patch exists@
    identifier fn =~
    "^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
    identifier a, b, c;
    expression e;
    position p;
    @@
    
    (
    - #define fn(a, b, c) e
    + #define fn(a, b) e
    |
    - #define fn(a, b) e
    + #define fn(a) e
    )
    
    Link: http://lkml.kernel.org/r/20181108181201.88826-2-joelaf@google.comSigned-off-by: default avatarJoel Fernandes (Google) <joel@joelfernandes.org>
    Suggested-by: default avatarKirill A. Shutemov <kirill@shutemov.name>
    Acked-by: default avatarKirill A. Shutemov <kirill@shutemov.name>
    Cc: Michal Hocko <mhocko@kernel.org>
    Cc: Julia Lawall <Julia.Lawall@lip6.fr>
    Cc: Kirill A. Shutemov <kirill@shutemov.name>
    Cc: William Kucharski <william.kucharski@oracle.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    4cf58924
pgalloc.h 1.81 KB