• Joel Fernandes (Google)'s avatar
    mm: treewide: remove unused address argument from pte_alloc functions · bef22eb7
    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 avatarStephen Rothwell <sfr@canb.auug.org.au>
    bef22eb7
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