Re: [PATCH -mmotm-2009-12-10-17-19] Fix wrong rss count of smaps
From: KAMEZAWA Hiroyuki
Date: Sun Dec 27 2009 - 23:51:13 EST
On Mon, 28 Dec 2009 13:46:19 +0900
Minchan Kim <minchan.kim@xxxxxxxxx> wrote:
>
> I am not sure we have to account zero page with file_rss.
> Hugh and Kame's new zero page doesn't do it.
> As side effect of this, we can prevent innocent process which have a lot
> of zero page when OOM happens.
> (But I am not sure there is a process like this :)
> So I think not file_rss counting is not bad.
>
> RSS counting zero page with file_rss helps any program using smaps?
> If we have to keep the old behavior, I have to remake this patch.
>
> == CUT_HERE ==
>
> Long time ago, We regards zero page as file_rss and
> vm_normal_page doesn't return NULL.
>
> But now, we reinstated ZERO_PAGE and vm_normal_page's implementation
> can return NULL in case of zero page. Also we don't count it with
> file_rss any more.
>
> Then, RSS and PSS can't be matched.
> For consistency, Let's ignore zero page in smaps_pte_range.
>
> CC: Matt Mackall <mpm@xxxxxxxxxxx>
> Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
BTW, how about counting ZERO page in smaps ? Ignoring them completely sounds
not very good.
Thanks,
-Kame
> ---
> fs/proc/task_mmu.c | 3 +--
> 1 files changed, 1 insertions(+), 2 deletions(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 47c03f4..f277c4a 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -361,12 +361,11 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
> if (!pte_present(ptent))
> continue;
>
> - mss->resident += PAGE_SIZE;
> -
> page = vm_normal_page(vma, addr, ptent);
> if (!page)
> continue;
>
> + mss->resident += PAGE_SIZE;
> /* Accumulate the size in pages that have been accessed. */
> if (pte_young(ptent) || PageReferenced(page))
> mss->referenced += PAGE_SIZE;
> --
> 1.5.6.3
>
>
>
> --
> Kind regards,
> Minchan Kim
>
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