Re: [PATCH] rmap: fixup page_referenced() for nommu systems

[Greg Ungerer]

Mike Frysinger wrote:
> After the recent changes that went into mm/vmscan.c to overhaul stuff, we
> ended up with these warnings on no-mmu systems:
> mm/vmscan.c: In function âshrink_page_listâ:
> mm/vmscan.c:580: warning: unused variable âvm_flagsâ
> mm/vmscan.c: In function âshrink_active_listâ:
> mm/vmscan.c:1294: warning: âvm_flagsâ may be used uninitialized in this function
> mm/vmscan.c:1242: note: âvm_flagsâ was declared here
>
> This is because the no-mmu function defines page_referenced() to work on
> the first argument only (the page).  It does not clear the vm_flags given
> to it because for no-mmu systems, they never actually get utilized.  Since
> that is no longer strictly true, we need to set vm_flags to 0 like everyone
> else so gcc can do proper dead code elimination without annoying us with
> unused warnings.
>
> Signed-off-by: Mike Frysinger <vapier@xxxxxxxxxx>

Acked-by: Greg Ungerer <gerg@xxxxxxxxxxx>



>  include/linux/rmap.h |    9 ++++++++-
>  1 files changed, 8 insertions(+), 1 deletions(-)
>
> diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> index 216d024..bf116d0 100644
> --- a/include/linux/rmap.h
> +++ b/include/linux/rmap.h
> @@ -118,7 +118,14 @@ int try_to_munlock(struct page *);
>  #define anon_vma_prepare(vma)	(0)
>  #define anon_vma_link(vma)	do {} while (0)
>  
> -#define page_referenced(page, locked, cnt, flags) TestClearPageReferenced(page)
> +static inline int page_referenced(struct page *page, int is_locked,
> +				  struct mem_cgroup *cnt,
> +				  unsigned long *vm_flags)
> +{
> +	*vm_flags = 0;
> +	return TestClearPageReferenced(page);
> +}
> +
>  #define try_to_unmap(page, refs) SWAP_FAIL
>  
>  static inline int page_mkclean(struct page *page)

--
------------------------------------------------------------------------
Greg Ungerer  --  Principal Engineer        EMAIL:     gerg@xxxxxxxxxxxx
SnapGear Group, McAfee                      PHONE:       +61 7 3435 2888
825 Stanley St,                             FAX:         +61 7 3891 3630
Woolloongabba, QLD, 4102, Australia         WEB: http://www.SnapGear.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/