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    Subject[PATCH] mm: make expand_downwards symmetrical to expand_upwards
    Hi,
    the following patch is just a cleanup for better readability without any
    functional changes. What do you think about it?
    ---
    From 71de71aaa725ee87459b3a256e8bb0af7de4abeb Mon Sep 17 00:00:00 2001
    From: Michal Hocko <mhocko@suse.cz>
    Date: Fri, 15 Apr 2011 14:56:26 +0200
    Subject: [PATCH] mm: make expand_downwards symmetrical to expand_upwards

    Currently we have expand_upwards exported while expand_downwards is
    accessible only via expand_stack.

    check_stack_guard_page is a nice example of the asymmetry. It uses
    expand_stack for VM_GROWSDOWN while expand_upwards is called for
    VM_GROWSUP case. Let's make this consistent and export expand_downwards
    same way we do with expand_upwards.

    Signed-off-by: Michal Hocko <mhocko@suse.cz>
    ---
    include/linux/mm.h | 2 ++
    mm/memory.c | 2 +-
    mm/mmap.c | 2 +-
    3 files changed, 4 insertions(+), 2 deletions(-)

    diff --git a/include/linux/mm.h b/include/linux/mm.h
    index 692dbae..765cf4e 100644
    --- a/include/linux/mm.h
    +++ b/include/linux/mm.h
    @@ -1498,8 +1498,10 @@ unsigned long ra_submit(struct file_ra_state *ra,
    extern int expand_stack(struct vm_area_struct *vma, unsigned long address);
    #if VM_GROWSUP
    extern int expand_upwards(struct vm_area_struct *vma, unsigned long address);
    + #define expand_downwards(vma, address) do { } while (0)
    #else
    #define expand_upwards(vma, address) do { } while (0)
    +extern int expand_downwards(struct vm_area_struct *vma, unsigned long address);
    #endif
    extern int expand_stack_downwards(struct vm_area_struct *vma,
    unsigned long address);
    diff --git a/mm/memory.c b/mm/memory.c
    index ce22a25..f404fb6 100644
    --- a/mm/memory.c
    +++ b/mm/memory.c
    @@ -2969,7 +2969,7 @@ static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned lo
    if (prev && prev->vm_end == address)
    return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;

    - expand_stack(vma, address - PAGE_SIZE);
    + expand_downwards(vma, address - PAGE_SIZE);
    }
    if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
    struct vm_area_struct *next = vma->vm_next;
    diff --git a/mm/mmap.c b/mm/mmap.c
    index e27e0cf..6b2a817 100644
    --- a/mm/mmap.c
    +++ b/mm/mmap.c
    @@ -1782,7 +1782,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
    /*
    * vma is the first one with address < vma->vm_start. Have to extend vma.
    */
    -static int expand_downwards(struct vm_area_struct *vma,
    +int expand_downwards(struct vm_area_struct *vma,
    unsigned long address)
    {
    int error;
    --
    1.7.4.1
    --
    Michal Hocko
    SUSE Labs
    SUSE LINUX s.r.o.
    Lihovarska 1060/12
    190 00 Praha 9
    Czech Republic


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