On Thu, Nov 28, 2013 at 04:48:42PM +0900, Joonsoo Kim wrote:
> There are a lot of common parts in traversing functions, but there are
> also a little of uncommon parts in it. By assigning proper function
> pointer on each rmap_walker_control, we can handle these difference
> correctly.
>
> Following are differences we should handle.
>
> 1. difference of lock function in anon mapping case
> 2. nonlinear handling in file mapping case
> 3. prechecked condition:
> checking memcg in page_referenced(),
> checking VM_SHARE in page_mkclean()
> checking temporary vma in try_to_unmap()
> 4. exit condition:
> checking page_mapped() in try_to_unmap()
>
> So, in this patch, I introduce 4 function pointers to
> handle above differences.
>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
>
> diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> index 0f65686..58624b4 100644
> --- a/include/linux/rmap.h
> +++ b/include/linux/rmap.h
> @@ -239,6 +239,12 @@ struct rmap_walk_control {
> int (*main)(struct page *, struct vm_area_struct *,
> unsigned long, void *);
> void *arg; /* argument to main function */
> + int (*main_done)(struct page *page); /* check exit condition */
> + int (*file_nonlinear)(struct page *, struct address_space *,
> + struct vm_area_struct *vma);
> + struct anon_vma *(*anon_lock)(struct page *);
> + int (*vma_skip)(struct vm_area_struct *, void *);
Can you add some comments about how these callbacks work and when it
should be set to for future users? For example, anon_lock() are
used to override the default behavior and it's not trivial.
> + void *skip_arg; /* argument to vma_skip function */
I think that it's better to move this field into the structure pointed
to by arg (which can be defined by each caller in its own way) and pass
arg to *vma_skip().
Thanks,
Naoya Horiguchi
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